texts:
This is the solution I saw for the equivalent resistance:
"12 and 60 ohm resistors are in parallel. Hence, 12//60 = 10 ohm. This 10 ohm
and 20 ohm are in series to give 30 ohm. This is in parallel with 30 ohm to give
30//30 = 15 ohm. And 25//(15+10) = 12.5. Thus R = 5 + 12.5 + 15 = 32.5 ohm"

I would really appreciate a circuit diagram solution, one that shows the circuit after each step so that I can properly understand the solution.

simulate this circuit – Schematic created using CircuitLab

Figure 2. CircuitLab version for OP to work on [by Transistor].


texts: I have searched a lot and I can't seem to find a micro-controller that I can program in C++. Can someone please help me find a micro-controller (besides Arduino) that I can program C++?


texts: Operational amplifier as a comparator at high frequency

texts:
I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.

So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak)  and frequency 100 Hz and 5 kHz.

At low frequency (say 100 Hz), the output is good
At high frequency (say 5 kHz), the output is too bad.

What will be the problem...

If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.

Calculation of slew rate for a sinusoidal signal...

Slew rate= Vm * 2pi * Frequency

     = 5 V * 2pi* 5000 Hz

     = 1570796 volt per second or 0.15 V/µs

Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.

Where am I wrong?


texts: Operational Amplificator Association effect on Slew Rate

texts:
I am designing a circuit which means getting sinusoidal signal as as Input and pass it to an ADC.
Since the ADC supports tensions from 0V to 5V and my input 5Vpp, then I need to escalate it properly  (to 2.5Vpp)then shift it 2.5V

My first thought was the following:

The first AmpOp (IC1A) is to isolate the input from the circuit from the protection zeners.
The second AmpOp (IC1D) is to escalate it to 2.5Vpp.
The third AmpOp (IC1B) is to sum the input with 2.5V provided by the tension divider.

Which leads me to concern about (R5 series R6)//(R9 series R8) unintentionally; Problem solved adding a forth (IC1C) AmpOp between them.

But I got concerned about how the slew rate would be affected by associating so many AmpOps. I mean, my idea is to run it with ideally 1Mhz, and my SR is 2.9V/us. Any ideas?

(Actually I tried to reconsider each one of this ampOps, so things stay stable. The first one I could substitute by a really big resistor, and the second one for a tension divider, it'd be better maybe?)

I appreciate any thought about it


texts:
I'm working on a project were I need to cut the power going to the ignition coil on a motorbike (produces pretty high voltages) for small amounts of time using an arduino. The switching needs to happen very fast.

I was planning to go for a MOSFET (P-Channel) since, even if the Arduino malfunctions for some reason the coil will still get power. But, again, for some reason if the MOSFET gets damaged will the connection remain closed or will it be open ?
Also, will a MOSFET be the best option here ?

EDIT:
Switching would need to happen under 100ms.


texts: undefined delay of pixel data from image sensor

texts: Would it be possible for MCUs to capture valid pixel data from Sony's IMX225LQR-C image sensor? On page 49 of this datasheet it's written that the sensor generates sync codes to distinguish between invalid pixel data and valid pixel data. When Vsync and Hsync signals are given, then processor needs to wait for specific SAV(Start of Active Video) values in the pixel data pins(D0~D11). After identifying the specific 12-bits values, your processor should capture the pixel data until it receives EAV(End of Active Video) values. The pixel clock is 74.25Mhz, which is quite high. Then would it be possible for MCUs in general or for Atmel's SAMA5D2 to capture video from this image sensor?


texts: Switching characteristics in terms of TTL flip flops

texts:
I am a complete novice when it comes to electrical things. Fine at digital logic, haven't done electricity since high school.
I'm looking at flip flops and I've run into something called switching characteristics:

Can I safely assume what it means is if I am running this flip flop at 200MHz it just means it would take 200MHz to switch over, or does it mean that the minimum speed of this flip flop is 200MHz at 1.2V?
I don't intend to run this thing at 200MHz, but a lot of these flip flops come with MHz ratings and I want to be sure there isn't a minimum speed I need to hit.
Also sorry for asking this basic question, but I'm so new to electronics that I can't effectively google my answers.


texts: Recording bioelectrical activity in plants- will this circuit work- any advice on sensors?

texts:
I am a visual art student and I'm currently developing a project which involves recording bioelectrical activity in plants. I am totally new to this game so I’m just wondering if anyone can have a look at this circuit to see if it might work.

The NC on the image means not connected. I've never drawn up a circuit before so I had to run wire over other wires. The circuit diagram just shows where connections are.

I used falstad to make it http://www.falstad.com/circuit/  The left hand side of the circuit gives a negative voltage for the Op amps to work. The right hand side of the circuit with 3 op amps is the instrumentation amp which is supposed to take the small signal of the plant and subtract all the noise I don't want and then amplify it for an arduino to read.

I'm also wondering if anyone has any advice on what sensors to use.

Please let me know your thoughts.


texts: Does Hall flow sensor require an optocoupler when using STM32 MCU?

texts:
I'm using an STM32F103 to measure water flow through a pipe using Hall flow sensors. My power supply is 12V DC to 5V/3.3V DC. STM works with 3.3V and Hall sensors with 5V levels. I've configured the TIM4 as Input Capture and connected it directly to the flow sensor output and I'm counting the number of ticks per second to determine the flow.

What I've noticed is that even when there is no flow, the sensor gives out random values. To the same PS I also have connected an LCD display, 2x Hall flow sensors, a 555 timer, and 2x STM32s. What I want to know is will this issue be solved by just using optocouplers on every input from Hall sensor to the GPIO pin? I'm thinking since all of these devices have a common ground there is a lot of noise in the system, but maybe the issue is something else?


texts:
I am using an NE5532 as a voltage follower/buffer in an audio circuit and am having some noise issues. I’ve simplified the circuit to isolate the issue. The audio input signal comes in through an audio transformer to the +IN on the amp.  The amp output is currently going directly into a commercial mixer for testing.

With the mixer gain and volume turned up and no sound signal, rather than quiet white noise/background static I’m getting a relatively loud/fast ticking/flapping sound … sounds something like shuffling cards, but more of a ticking. With an input signal, it’s loud enough to interfere with the music.  There are also some blips of loud static every second or so.  For testing I replaced the op amp with an LM411 FET amp, the noise was mostly gone, except for the ticking being very very faint at full volume.  I have tried all different combinations of grounding, and transformer isolating outputs, nothing helps, it seems to be an op amp issue and the noise is in the signal itself.

I’ve tried scoping the output, and can’t distinguish the ticking noise and blips from noise measuring from only the original source.

Any idea what is causing this and how to fix it?

Another thing: This amp is used as a buffer prior to output with line level signals up to 2Vrms. According to the datasheet, excessive current is drawn at a differential input of 0.6V due to the input transistors. Should I be modifying my circuit with input resistors or something, or should this amp only be used with small input signals?

A few things: The final circuit is much more complex, this is basically what I've simplified it to just for isolating the noise issue. The final circuit is single-ended +12VDC, with opamp biased to +6V, and power supply is +15VDC switcher with heavy filtering and +12V linear regulator. Regardless of how I power the circuit, whether +15V switcher with filtering or a linear 12V bench supply, I get exactly the same noise as described. Input to mixer is balanced.

Update: Here are the additional tests I've completed trying to isolate this noise problem. All have been unsuccessful so far:
1) I was able to measure from 3-12mVAC between completely unused traces even with no power on the breadboard and discovered that this was causing some hum, so I deadbugged the circuit. Same result.
2) I've tried adding an LC filter w/ 500kHz cutoff after the opamp to eliminate RF interference, same result.
3) I've tried a different brand mixer after discovering the jack shields on the first were not chassis grounded. The original used a linear supply, this one a switchmode supply. No change either way.
4) After measuring 45VAC to ground on the new mixer chassis, I've tried variations of earth grounding the mixer chassis through the bench supply. This eliminated the massive hum I'd get without doing it, but the opamp noise is still there.
5) I've tried both unbalanced and balanced inputs, no change.
6) I've tried multiple variations of different cables, plugs and adapters, headphones and shielding the cables. No change.

The only thing I can think of left is that it's something with the opamp itself. As originally mentioned, an LM411 reduced the noise significantly, although it was still there. I'm attaching an overview of the system setup, I apologize for the poor quality. The drawing is mainly to isolate any potential ground loops, so the internals of the devices may not be entirely accurate, I only verified where GND and COM were connected. Is there a way to attach an audio file to this post? Maybe someone will recognize the noise. Not experienced with the phenomenon, but I think it may be motorboating.

Thanks so far for the troubleshooting input, any other comments are greatly appreciated.


texts: Control relay with two devices, where one can override the other

texts:
Disclaimer: I am not an electrical engineer. I understand the logic of what I want, but I do not know which components are available to solve my problem. Please be gentle.
This is what I have:

I have a device A that puts ground (-31) on a wire when in rest. I can deactivate and reactivate this externally, so I can use it like an on/off switch.
I have a device B that puts ground (-31) on a wire when it is active and 'nothing' when it is inactive.
I have a relay C that connects when it receives a ground (-31), allowing the mechanism behind it to function, like an on/off switch. The relay also receives a +15 as general power supply to do its magic.

This is what I want:
I want to hook up device A and B to the relay C in such a way that:

When device B activates, the relay disconnects forever until device A overrides it by being activated (or deactivated and then reactivated, if need be), regardless of the current state of device A.
If device B deactivates, the relay is still disconnected. If device B activates again, the relay is still disconnected.
When device A deactivates, the relay disconnects until device A reactivates.

Simply put: device A controls the relay and acts as manually operated master override, but device B can interject regardless of the state of device A.
What component(s) do I need between A, B and C to get the behavior I am looking for, and am I making any sense? :)
Timing diagram (edit: now shows system in rest as active as described):


texts: Simple NMOS transistor circuit output impedance

texts:
I am having trouble figuring out the best way to determine the output impedance of this simple NMOS transistor circuit:

Both transistors are equal, and the body effect is ignored.

What method should I use to find the output impedance? Should I find the transistors' small-signal equivalent and then use Thevenin and simply add resistances of both transistors together, or is there another method I could use?

Also, won't the output impedance vary with the drain current? Will it then be a function of \$V_{\text{ref}}\$?

EDIT:

I have tried to reduce the circuit down to its small signal equivalent using the t-model for an active NMOS. Is this correct?

EDIT 2:

Can the small signal equivalent circuit be reduced using Thevenin into something like this?

I feel like I am missing something here. It just seems too easy to be true.


texts: Tips for an old previous and renewed embedded programmer

texts:
Background -

I programmed my first SBC on an MEK6800D2 evaluation Kit (that I had build) in the late 70's and other boards of that time like the Rockwell 6502 Kim-1, 8085, etc. Now I'm a 61 a Big Box MS C# vs2010 programmer, but my real interest has always been embedded, but it's been oh so many years. Now that I'm close to retirement I would like move to recreation programming back to my roots of embedded. C, objective C, ASM, other? (OK I draw the line at forth).

Inquiry -

So now I'm looking at the latest embedded chip sets and oh wow I only understand about half of it. Is there a resource, you might recommend for someone like me? Books, Sites etc. ?

BTW - I've found this particular stack exchange style site very useful. many Thanks


texts:
Wondering if anyone is aware of a way to cause an ultrasonic proximity sensor to be modded, such that, it's forward line-of-sight range remains unaffected, but it's angular spread is reduced, somewhat in the "collimator" sense (in terms of light). To explain the problem, I've been experimenting with the el-cheapo HC-SR04 sensor, trying to detect level of water in a plastic bucket (25 ltr vol.). While I am not 100% sure, but I think the diameter of the bucket it is a problem, that, even when the level of water is low (about 18-19 inches away from the sensor), I get a reading that translates to about 8 inches. Only explanation I have is that the sonar is reading the waves bouncing off the bucket walls.

I was wondering if some kind of a collimator built using sound-absorbing material, might work ? I will try experimenting with low density foam (Styrofoam perhaps) but not quite sure if it's really sound-absorbing.


texts:
It is the first time for me to design a PCB with a PCIe bus. My first design failed, the bus is not working!

Tom helped me in this question and instructed me how to correctly route a high speed bus - thanks!
Ethernet controller not recognized on PCIe bus

I now improved my design, but before spending some more hundred bucks I would like to make sure this should work. Does my routing now look ok? Ground planes and ground vias are not shown.


texts: Extraneous loop produced by PIC compiler from MicroChip

texts:
We're using the Lite version of the MicroChip PIC compiler so maybe that's the reason, but this simple one-bit shift is generating a loop where none is necessary. Since the shift count is 1 (a constant), I would expect the compiler to create no loop—an elementary optimization.

Is there a compiler optimization switch that would alleviate the loop?
Here is the code for the shift:

    long foo;   // a 32-bit value

// Shift foo one bit.
// A one-iteration loop is created!

    foo >>= 1;

And here is the compiler-generated code. As you can see, the shift is wrapped with a one-iteration loop.

  07F6    3001     MOVLW 0x1
  07F7    00F2     MOVWF 0x72
  07F8    37F6     ASRF 0x76, F
  07F9    0CF5     RRF 0x75, F
  07FA    0CF4     RRF 0x74, F
  07FB    0CF3     RRF 0x73, F
  07FC    0BF2     DECFSZ 0x72, F

EDIT

Compiler Version: HI-TECH C Compiler for PIC10/12/16 MCUs (Lite Mode)  V9.81


texts: I am doing a hobby project and I found a place to get PCB HDMI jacks and I wanted to incorporate an HDMI switch into the board. My question, is there an IC that I can use as the "switch". It will be like a standard 5-1 switch. at the very least if someone could point me in the right direction.


texts: How much current can a 0.1" pitch pin header pass?

texts: I'm curious how much current it is safe to pass through a 0.1" pitch pin header. I'm sure it will depend on the gauge and stranding of the wire attached to it as well, but assuming that is not the limiting factor how much could be safely passed?


texts: From zero to "almost pro": Newbie trying to learn. Good, quick resources?

texts:
I am a total zero in electronics. I just know what is a resistor and what is a capacitor. I also know what is a 555 just because I've been told what it does, 15 years ago. Apart from this and a bunch of other names, nothing more. However, I do have advanced knowledge of math and physics.
I would like to learn electronics. The quicker the better, but without wacky stuff and practical exercises. I am not going to implement the circuits practically. I don't want to make my own blinking LED or my own crystal radio. I'd like instead to know what are the characteristics of the many components (transistor, zener diode, FET, MOSFET, whatever), when it's appropriate to use them and why, how to design a circuit and balance the components etc. In other words, I want to understand. I don't want to do (I'd like to, but I can't for lack of space).
Where can I find resources (either books or online tutorials) to achieve this goal?


texts:
A recurring problem with analogue potentiometers is to get a stable output that only changes when the pot is actually moved (i.e. it doesn't output a lot of extremely similar values due to noise or jitter). What is the best approach to account for this?

I can think of a couple of approaches:

Timeout: enable a deadzone after a second or two if the knob isn't moved by a certain amount.
Moving deadzone: every time the read value leaves the deadzone, recenter it on the new value.

Note that pure filtering doesn't solve the problem - when you quantise the filtered value it can always be half-way between two quantisation levels and flutter between them.

Does anyone have any more solutions?

Edit: To be clear, this is why averaging, filtering, a better potentiometer, ignoring the LSB etc won't work:

Suppose we have this voltage after filtering/averaging whatever:

Then suppose we quantise to the nearest 0.1. We'll get an output that jitters around:

Hopefully you can see that no matter how good your filtering, or how coarse your quantisation, there will always be the possibility of jittering. That is why you need something other than really good filtering or really coarse quantisation.

Edit 2: To be doubly clear, because it seems some people aren't getting this. I would like some method to completely eliminate this kind of jitter (which is caused by unavoidable noise in the system), while still responding 'nicely' to a user physically turning the pot (it's for a brightness knob).

Edit 3: To be triply clear (come on guys), I only want the value to change when the pot has been physically moved because acting on these changes is costly (the display flickers when the brightness is changed; I don't want it flickering continuously).


texts:
Let's assume there is an emitter and a reciver. As the emitter is usually omni-directional, the reciver may get one direct wave and some reflected waves.
Why does not these waves influence each other (they might even cancel themselves) and how it is solved the latency issue (a packet comes faster on direct wave than on reflected waves)?


texts: Print std_logic_vector in hexadecimal (VHDL)

texts:
I have an 8-bit std_logic_vector and I would like to print its value (during simulation) as a 2-digit hexadecimal value.

Current code:

report "Entity: data_in=" & integer'image(to_integer(unsigned(data_in)));

Current output:

Entity: data_in=16

Desired output:

Entity: data_in=10h

What would be the most painless way to achieve this?


texts: Interpreting ideal diode plot with resistor

texts: I don't understand how the gradient is 1/R_d or how the resistor is limiting the current.


texts: Altium: i-dots in soldermask layer disappear in Gerber

texts:
I have my email address embedded in the soldermask layer.
When checking the generated Gerber data, the dots on all the "i"s are missing.

How did that happen?


texts:
A friend of mine gave me this circuit to discharge a 3V7, 5000mAh single-cell LiPoly accu:

simulate this circuit – Schematic created using CircuitLab

The zener is to make sure that the circuit stops when the voltage gets below 2V7, so that the accu doesn't get below the critical voltage of 2V4.

However, this doesn't work. The voltage over the zener is approximately 1V, the voltage over the resistor 2V7. Now the resistor gets a little warm, but more important, the circuit won't stop at 2V7 but at 1V. Am I right?

How can I change the circuit to make it work?


texts: problem in adding IP to platform designer

texts:
I'm new to platform designer and I want to add an ALT PLL intel FPGA IP to a platfrom designer project but after opening Mega wizard plugin manager and setting up the requirements, IP does not add to project!!!
qurtus version: Qurtus Prime lite edition 20.1.
operating system: ubuntu 20.04 LTS.
Device Family: Max 10.
I found a link from Intel website that refers to same problem but without solution.
More description:
I can add any other IP core but my only problem is with this particular IP and there is no problem in Windows version.


texts: How can I put dimension relative to component center in Altium Designer?

texts:
I have an Altium Designer PCB with some tactile switches.

In the same project a have a "Dimensions" layer where I specify important dimensions to be passed to the PCB manufacturer and the case design team in our company.

Placing dimensions of the board outline is very easy to me, but I'm unable to find a way to place a dimension relative to the center of an object (switch or IC for example).

I tried to open the component properties and add some axes to the component in the hope they would be an 'snap object' to the dimension tool, but the axes does not show in the GUI.

Does anyone knows how to place a dimension relative to component center?


texts: Why are the SRAM data and address pins numbered?

texts:
As far as understand, it would make no difference to the operation of an SRAM if you mixed up the order of the address or data pins.

E.g. http://www.farnell.com/datasheets/1911297.pdf?_ga=2.220805788.545458806.1537605448-1970519925.1482350159

Removable non-volatile chips, such as PROMs and EEPROMs, have address and data pin numberings defined, as they need to be consistent across programmers and application circuits.

Why do SRAM chips have numbered data and address pins?

Is there any operation impact if I swap address pins around to make a PCB easier to route?


texts: How many customers can be connected to a Single Wire Earth Return node/pole in a power grid

texts:
I'm new to Electrical Engineering, and have a course in Technical communication, we will deliver a suggestions about a power grid. I'm afraid my current knowledge reaches little more then node analysis.

The course revolves around a project in which each group will deliver a report on different technology in different contexts. My group is tasked with designing a power grid with available technologies, we included 3-phase, SWER and direct DC current. This report if it's worth a wile will be part of the discussion making in the real world implementation in a village in Tanzania.

Me myself has taken on the task of "designing" a SWER power grid. Doing this I will estimate a cost per km. Since I plan to argue that poles and lines can be locally acquired the cost will be the cost of the hardware, which now seemingly to depends on how many costumers that can be connected to the sam pole or node in the grid.

I can't seem to understand or get a grips on how many customers that can connect to the same SWER or Single Wire Earth Return pole.

My hope that many customers can connect to the same transformer.

The SWER 19kV line will connect about 200-300 customers in a rural area of 38km2. And is one of 3 technologies presented.

So my question is, how many customers/households/consumers can be connected to a pole in a SWER power grid?


texts:
I am planning on building a quite large USB hub, which final use is to connect, charge and sync let's say 40 iPads. The iPad electrical specification from Apple states that each unit needs to have available 5v/2.1A from the USB bus power to charge fast.

I still don't know if I'm gonna build the USB hub from scratch or I'm gonna buy a few cheap hubs and bridge them together, but the main question is: if I need the devices just syncing, I need 500mA in each port, which means 0,5*40 = 20A.

Does that mean I can accomplish that by removing the +5v wire coming from the PC port (or placing a diode) and powering the same path with a massive 5v/20A power supply? Will this work as expected? Isn't there risk of "burning" the USB devices or the computer?


texts: In what order should I isolate and attenuate an audio signal?

texts:
I have a cheap bluetooth audio module (with no documentation) that outputs a signal greater than line-level.  It was probably designed to be connected directly to small speakers, since the ground on the output signal is floating.

I'm trying to connect it (as line-level) to the input of a more powerful amplifier.  I assume that a potentiometer is a reasonable way to adjust the signal level, but should I put it before or after the isolation?

In other words, should I do it like this:

simulate this circuit – Schematic created using CircuitLab

Or like this:

simulate this circuit

Or some other way entirely?  Assuming that I'm on the right track, what value of potentiometer should I be using?


texts:
Can someone tell me if am I right?
In constant voltage mode the op amp compares the voltage on the non-inverting input with the voltage on the inverting input and when U+ is larger than U- the load MOSFET turns on?


texts: Is there a way to store matrices in an FPGA?

texts:
I just finished a Coursera course on hardware design (nand2tetris) and I want to take the next step and implement the design in an FPGA. Being fairly new to the hardware aspect of computing in general, I needed to clear a few questions regarding memory. In particular, I want to implement a memory design that is organized into square arrays of 16 bit wide registers. The data would be accessed by specifying an array and then either a row or column (with the goal of expediting matrix multiplication). However, I am unsure if such a design will fit into an FPGA (I believe I can afford at most a Cyclone V or something equivalent). Since GPUs can be implemented on FPGAs, there must be a more efficient way of doing this that does not require using the D flip flops in each logic element to store a bit from an individual register. If there is not, how do people handle arrays of data in parallel on FPGAs?
Any information would be really helpful and since this is all a purely pedagogical exercise, pointers to learning materials on the subject are appreciated.


texts: Error (209015): Can't configure device. Expected JTAG ID code 0x02D010DD for device 2, but found JTAG ID code 0x00000000

texts:
I'm having a weird problem where i cant upload my design to the  DE0-NANO board, gives me the weird error message which is the title of this question.

Any other design uploads fine and I have done nothing different. Restarted the computer, rewrote the project, checked if the correct device is chosen and updated all the drivers, still doesn't upload.

Any suggestions?


texts: Easiest way to generate 25V speaker signal

texts:
I have a fire alarm that accepts a 25v line level speaker input at 4w, what is going to be the easiest way to play arbitrary signals over it i.e. from a 3.5mm jack, an amplifier and a transformer? are there small pre built modules for this purpose? Everything I see seems like it is intended for distribution to a large pa system not a signal speaker.

Edit:
It is a SSPK24-75WR
Here are some datasheets I could find, but there is not mutch info beayond "hook it up to our system"
http://resource.boschsecurity.us/documents/Datasheet_SSPK_Famil_Data_sheet_enUS_2736837259.pdf

https://www.gentex.com/sites/default/files/551-0070%20SSPK24WLP%20Series_0.pdf

http://www.thesignalsource.com/documents/sspk.pdf


texts: How do I splice multiple (more than two) wires in-line?

texts:
When I look at many wiring diagrams, like this one:

(source),

I see wires which need to be connected to multiple points. This suggests that the wire will require multiple three-way splices in order to connect to all the right places. How is this done? I found 3-way heatshrink adapters (like this one: http://www.genuinedealz.com/3-way-wire-splice-butt-connector-w-adhesive-heat-shrink-12-10-awg), but that doesn't seem like an elegant solution. What is the correct approach here?


texts: Getting trouble powering a LED strip with battery

texts:
I'm trying to build a portable LED light and things are happening not the way I wish to.

I have a Sumbulbs 12036 LED COB Strip. This LED works with DC 12-14V voltage, it has 10W power and recommended current of no more than 600mA. Here is the link for this LED.

I mounted an aluminum panel on back to ensure a good heat dissipation. The first thing I did was test the LED using a transformer that output DC 12.8V and current of 520mA. I kept the light turned on a few hours and everything looks ok.

Now as I need it portable, I changed the source to one 18650 battery but it doesn’t work. In addition to the battery I used a MT3608 to boost the voltage but it works only for a short time (few minutes). The battery voltage goes down very soon and the LED's light is very very low.
My question is how can I use this LED with batteries? Thank you in advance for any advice.


texts: How to determine dielectric constant and loss tanget of a PCB board at a specific frequency?

texts:
I need to know dielectric constant (relative permittivity) and Tan loss of a FR4 board at 2.45 GHz.

The specification of the manufacturer is as it is below:

Dielectric Constant:

Test method (IPC-TM-650): 2.5.5.2
Test condition: Etched/@1 MHz
Specification(IPC-4101C) <5.4
Typical value: 4.58

Loss Tanget:
 - Test method (IPC-TM-650): 2.5.5.2
 - Test condition: Etched/@1 MHz
 - Specification(IPC-4101C) < 0.035
 - Typical value: 0.022

I read on the Net that those values should be lower at higher frequencies. Is it possible to calculate/determine/predict those two values for 2.45 GHz?


texts: Using LPCxpresso with barebones LPC4337 board

texts:
I recently purchased a development board on eBay that will allow me to work with NXPs dual core LPC4337 ARM M4/M0 processor.

I have experience working with uVison4 from KEIL, for the FRDM-KL25 from Freescale, although I'd prefer to use the LPCxpresso environment from NXP.

With KEIL, all I'd needed was:

The chip header file which was just full of macros for definitions (such as LPC43xx.h)
The startup_(chip name).S file
and the system_(chip name).c/.h file

If I had those, I could make a main.c program, include them and boom I'm off and working.  The main reason I don't want to use KEIL in this application is because their multi-core support is sketchy where as LPCxpresso has been made by NXP to support the multi-core development.

With LPCxpresso, it isn't the same case with a bare-bones project.  Supposedly there are some files that are generated that tie into the development environment and it isn't explained exactly what I have to do with those files.

NXP has many examples of code, all of which have full drivers and everything.  Normally that'd be awesome, although I want to write my own drivers since I want to know exactly what is going on with as little overhead as possible.

I've asked on the LPCware forums but either they weren't too helpful or I just didn't understand them.  This guy seemed to have a similar issue but he didn't post an updated project with everything he got working.

My point is, I'm having a really hard time getting a bare-bones minimum working project going like I could in KEIL.  Has anybody been able to do this? Or what files do I need?


texts: alternative amplifier for vibration exciter (shaker)

texts:
I am using a second-hand LDS V201 permanent magnet shaker, and would like to use this to test and validate some monitoring equipment. I would like to generate signals suchs as sweep sines, but these do not need to be particularly "clean". I am aware that I need an amplifier to amplify the vibration signals (which  we are able to generate) but on contacting the manufacturer, the specific amplifier they recommend (LPA100) costs about £2000. This is above my budget but could stretch to this if necessary.

My questions:
What is special about amplifiers for shakers and could I use a less specialised amplifier for this purpose? Is there a "cheap and nasty" way of amplifying my signals?

Specs for shaker and recommended amp attached


texts: Measuring the Raspberry Pi power consumption

texts:
In my application I need to measure the power consumption of the Raspberry Pi 2 model B board under different conditions: taking pictures, compressing images, encrypting data etc.

As I don't have precision multi-meters with data logging, I thought of using an ADS1115 16bit ADC, hooking up a 0.1ohm shunt on the +5V power line and measuring the voltage drop related to the Pi voltage. The ADC would be connected externally to another device for storage (possibly another Rpi or an Arduino board).

I found an article that proposes this measurement setup:

Is that setup feasible? What are the implications?


texts: I have a SOT23 electronic part AEWU9 - where can I find a datasheet?

texts: I have a SOT-23 part with part number AEWU9 but couldn't find any datasheet on the net. Where can I search more for this part?


texts: How to read a rely ratings: compressor: 10(10)A, p.f.0.6? what does p.f.0.6 stand for?

texts:
just like title, I've got a specification of cooler controller, but do not know how to read them.
relay rating
compressor: 10(10)A,p.f.0.6
light:      4(4)A,p.f.0.6
Fan:        4(4)A,p.f.0.6

thanks for help


texts:
I am making a PCB with a component that is of the Package SO-8FL. The component is n-channel MOSFET NVMFS4C03N by ON Semiconductor and the datasheet is here.

I started to make the package in Eagle, but got stuck and didn't feel comfortable. It's a bit more complex than other packages. I've searched many libraries that are available for download, and have not found any that include the SO-8FL package.

I need to integrate this into my PCB schematic and board design in Eagle. Can someone point me in the right direction?

Thanks,
Blake


texts: I need help to design a circuit to suppress amp peaks

texts:
First: im new here and this is my first question so if you think that I should ask or behave in a different way, feel free to tell me.

The (My) Problem:
We run LEDs on a test stand with ~5V,2.3A
and have the Problem of brief (~20µs) disconnects between the LED and the power supply.
The disconnect is rapid, so that in some cases the supply will not shut down. In case that happens the voltage at the open contacts increases and there is an amp Peak ~>5A at the Moment of reconnection which destroyes the LED.

I my idea for a circuit to solve that issue was this one:

There should be a n-mos with a high power, low resistance Resistor in a series Connection in a parallel configation to the LED. The Gate Voltage should be taken of a voltage divider (someone mentioned to me that instead of R1 i should use a z-Diode, although they did not provide a reason for that) The increasing voltage should open the mosfet, wich creates a way to reduce the energy in the circuit and there is no peak when the LED is connected to the circuit again.

this one is similar, but there is an OP involved to drive the mosfet.

My aim is to simulate, build and test a prototype. It is not to create a PCB with the circuit yet.
Since Im quite a newbie when it comes to simulations in LTSpice and desinging real circuits I have some difficulties to turn my ideas into a running solution.

eg.

-I know i need a resistor before the gate of mosfet, but which one?

-Or how to choose a fitting OP?

-Wich Mosfet shall i use here?

-What are the next steps ?

Thank you for reading, i hope to find help here.


texts: Running AT90USB646/Atmega32u4 between 3.3V and 5V

texts:
I'm working on a battery powered project that will need the AT90USB646 µC. From the data sheet, I know it can take from 2.7V to 5.5V at 8MHz. However, apparently, lower voltages reduce power consumption tremendously.
I can't run it at 3.3V since I have LED's with a 4.2 V_f and I'd rather not do 2 separate power rails if I can avoid it. I'm hoping to supply it with a boost-converter output of 4.5-4.6V. The remainder of my circuit is simply some LED's, some switches, and a bluetooth chip fed regulated 3.3V.
Would there be any issues running the µC somewhere between 3.3V and 5V standards?


texts: Reading from CAN bus of a Chevrolet Cruze using an Arduino Uno

texts:
I'm using the Arduino Uno, CAN bus shield, and OBDII to DB9 Cable using  their provided libraries. I was only able to initialize it.

Readings:

While connected to the car:

CAN-High: 2.7 V - 3.0 V
CAN-Low: 2.4 V - 2.7 V

While not connected to the car:

CAN-High: ~2.4 V
CAN-Low: ~2.5 V

Note: in both cases the Arduino is connected to my PC via USB (for debugging).

Sample code:

#include <SoftwareSerial.h>   //Software serial port
#include <Canbus.h>

#define CBRxD 5  // CAN BUS RX
#define CBTxD 4  // TX

#define DEBUG_ENABLED  1

char buffer[512];  //Data will be temporarily stored to this buffer before being written to the file
char tempbuf[15];
char lat_str[14];
char lon_str[14];

int LED2 = 7;
int LED3 = 8;

boolean scan = true;

SoftwareSerial canbusSerial(CBRxD, CBTxD);

void setup() {
    Serial.begin(9600);
    canbusSerial.begin(4800);
    pinMode(0, INPUT);
    pinMode(BTTxD, OUTPUT);
    pinMode(LED2, OUTPUT);

    pinMode(LED3, OUTPUT);

    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);

    setupCanbus();
}

void loop() {
    char recvChar;
    if (canbusSerial.available()) {  // Check if there's any data sent from the remote CAN bus shield
        recvChar = canbusSerial.read();
        Serial.print("CAN: "+recvChar);
    }

    if (scan) {
        digitalWrite(LED3, HIGH);

        if(Canbus.ecu_req(ENGINE_RPM,buffer) == 1) {       /* Request for engine RPM */
            Serial.println(buffer);                        /* Display data on Serial Monitor */
        }
        Serial.println(buffer);

        if(Canbus.ecu_req(VEHICLE_SPEED,buffer) == 1) {
            Serial.println(buffer);
        }Serial.println(buffer);

        if(Canbus.ecu_req(ENGINE_COOLANT_TEMP,buffer) == 1) {
            Serial.print(buffer);
        }Serial.println(buffer);

        if(Canbus.ecu_req(THROTTLE,buffer) == 1) {
            Serial.println(buffer);
        }
        Serial.println(buffer);
        //  Canbus.ecu_req(O2_VOLTAGE,buffer);

        digitalWrite(LED3, LOW);
        delay(100);
    }
}

void setupCanbus() {
    while (!Canbus.init(CANSPEED_250)) {
        Serial.println("CAN Init");
    }
    Serial.println("CAN Init OK");
    delay(1000);
}


texts:
I need to calculate the exact sampling time or sampling rate for my setup on a STM32F205.
I have the ADC setup as follow:

ADC_DeInit();

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
ADC_CommonInitTypeDef ADC_CommonInitStructure;
ADC_InitTypeDef ADC_InitStructure;

ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div4;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_1;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);

ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC1, &ADC_InitStructure);

ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_3Cycles);

I have this form the STM32F20x reference manual

  Channel-wise programmable sampling time The ADC samples the input
  voltage for a number of ADCCLK cycles that can be >modified using the
  SMP[2:0] bits in the ADC_SMPR1 and ADC_SMPR2 registers. Each channel
  can be sampled with a different sampling time. The total conversion time is calculated as follows: Tconv = Sampling time + 12 cycles
  Example: With ADCCLK = 38 MHz and sampling time = 3 cycles: Tconv = 3
  + 12 = 15 cycles = 0.5 μs with APB2 at 60 MHz

But I don't really understand how to use it on my setup.

Any help is welcome and I will provide any extra info if needed.


texts: Help refining a current control loop circuit

texts:
As a follow up to this question. (Sorry if this linking other posts is wrong. I'm new to forums)
Will this design for an XHP70.2 LED Driver with arduino control work to the params specified?

TL;DR: its a 15A~7V LED driver Current control loop controlled from an Arduino PWM. I'm new to op-amps.

CRE2512-FZ-R003E-3 - https://www.mouser.co.uk/datasheet/2/54/cre-1388683.pdf

INA180A2IDBVR - http://www.ti.com/lit/ds/symlink/ina180.pdf

I have found components for the first Current Sense Amplifier stage. It will output 0v - 2.25V and so, as suggested, I think a unity gain differential amplifier would work for the second stage. (with a potential divider to take the Arduino control from 5v to 2.25v and a potential divider to take the second stage output down to 2v)

What would be a suitable amp? (ideally something similarly small as the SOT-23-5 INA108A2)
Is there a way to reduce the number of resistors so I don't need All Of R9 & R10 & R11 & R12 & R13?

Thanks in advance


texts: Why is this BJT Schmitt trigger producing a sine wave?

texts:
I am trying to build a Schmitt trigger from a pair of BJTs to convert a sine to a square wave.

The sine wave is from a Colpitts oscillator running at over 150 MHz. I want to measure the frequency using something like the SN74LV4040, which is why I want to square the sine wave somewhat.

This is the relevant part of the Schmitt trigger (with V1 representing the oscillator). Emitter current was set to 2 mA, high voltage to 3 V, low voltage to 2 V.

simulate this circuit – Schematic created using CircuitLab

But this is the output I get in LTspice.

Why am I getting a sine wave output from the Schmitt trigger?

This is the whole schematic (with some voltages plotted), if that helps:


texts: How can a Arduino (5v) power a device that operates on >12v?

texts: Say I buy a device that requires 25 volts to function, but I want to control it using my 5v arduino. How would I go about powering/controlling higher voltage devices?


texts: Purpose/Difficulties of having a common mode choke

texts:
This question is related to common mode choke.

I know I have asked this question a couple of times in this forum and I have also read related questions and answers. But I am not able to get the total clarity. I really appreciate it if someone could illustrate with an answer.

I received the below response when I asked a senior why he removed a common mode choke in our design.

"In brief, the purpose for having common mode choke is to suppress common mode noise that exists in the PCB.  We found out that it may be useful if there is no ground plane like in 2-layer designs but with 4-layer and greater, the ground impedance tends to be low enough that it won’t cause common mode problems.  The other reason is that for the common mode choke to work properly, it becomes a tough job in layout, you need to guarantee that there is no overlap between AGND and digital ground on all layers and you have to create a large puddle around the connector and you have to tie all the decoupling caps to that puddle with enough isolation otherwise noise will couple on the puddle and defeats the purpose for having a common mode choke.  It’s not necessary to go through this pain and actually may hurt EMC if it’s not done right."

I actually didn't get more clarity with his answer. I would really appreciate if someone could really provide a detailed answer with illustrations (related to layout). What is a puddle and can someone illustrate it?

For a bit clarity, this is an automotive design. The Battery and ignition lines, comes from the vehicle connector.

Request you to clarify on the topic with illustrations or simpler analogies for our benefit


texts: Getting Agilent USB GBIP Adapter to work with NI-Visa or R&S GBIP over USB with Agilent Visa

texts:
This Visa/IVI jungle is pretty much a desaster. Not enough that each package contains GBs or data, they also cause problems when installed in parallel (one example: https://www.mathworks.com/support/bugreports/1137571).

I have the Agilent 82357B USB-GBIP adapter with which I control an E3646A supply in MATLAB. It works well with the Agilent Visa drivers.

I also have a R&S SMW200A which I control over USB with MATLAB. This works nice the NI Visa drivers.

Installing both VISA drivers makes one stop.

Is it possible to make the Agilent 82357B work with the NI drivers or the R&S SMW over USB with the Agilent drivers?


texts: Wemos controled LED strip not turning off fully

texts:
I am trying to make a LED strip light controlled by wemos D1 mini with N-MOSFET. I have a working circuit but the led strip is not completely turned off when the wemos pin is low and I do not fully understand why.
Should I try to increase the pull down resistor value from 10k or is the circuit wrong?
I use IRLML2502 (specs) which can switch on 3.3V. Is it a good choice?
Another question is, is this going to sustain working let's say for 10h/daily without heatsink and frying?
Circuit note - 3.3V is the wemos pin.

simulate this circuit – Schematic created using CircuitLab
EDIT
Readings on the voltmeter says:

ESP pin off state - 0.0V
R2 off state - 4.5V

I see where the power is coming from. I removed the R2 and all is working now.
Why would R2 be needed there? M1 is charged off immediately anyway.
When the R2 is in the circuit
LEDs in mosfet off state are clearly visibly illuminated in lighted up room. All pictures are same camera settings - a bit underexposed. (From left - powered off, mosfet off, full brightness)


texts: Arduino + Current Sensor -> Not always working

texts:
I am trying to measure power consumption of devices by using an TA12-200 power sensor with a Arduino Uno board.

This sensor is using a 800 ohms resistor and a 1:2000 ratio.

My measure to get mAh seem to be working when using it on ultra basic device like a 40W light bulb. But as soon as I try it on device that internally use DC like a LCD screen or a soup mixer, I get too high result comparing to my multimeter.

Here is my Arduino code to calculate the power consumption :

float KNPwrSwitch::GetPowerConsumption()
{
        int sensorMax = 0;
 uint32_t start_time = millis();

 // Sample the max value for 1000 ms
 while ((millis() - start_time) < 1000)
 {
             float sensorValue = analogRead(_aPin);

             if (sensorValue > sensorMax)
                  sensorMax = sensorValue;
 }

 // Compute input voltage
        float vIn = (sensorMax * 5.0) / 1024.0;
       // Use Ohms law to compute intensity (A) (800ohms for TA12-200)
        float intensity = (vIn / 800) * 1000.0;
        // Use formula for SINE wave to convert to RMS
       float rms = intensity * 0.707;

  /*
   Current Transformer Ratio is 2000:1...

   Therefore current through 800 ohm resistor
   is multiplied by 2000 to get input current
  */
        float curThroughWire = rms * 2000;

  if (DEBUG_MODE) { Serial.println("Power Consumption"); }
  if (DEBUG_MODE) { Serial.println("-----------------"); }
  if (DEBUG_MODE) { Serial.print("Volts Peak : "); }
  if (DEBUG_MODE) { Serial.println(vIn, 3); }
  if (DEBUG_MODE) { Serial.print("Current Through Resistor (Peak in A) : "); }
  if (DEBUG_MODE) { Serial.println(intensity, 3); }
  if (DEBUG_MODE) { Serial.print("Current Through Resistor (RMS in A) : "); }
  if (DEBUG_MODE) { Serial.println(rms, 3); }
  if (DEBUG_MODE) { Serial.print("Current Through Wire (mA) : "); }
  if (DEBUG_MODE) { Serial.println(curThroughWire, 3); }

 return (curThroughWire / 1000) * 230; // This is supposed to be my Watts / hour consumption
}


texts: Help understanding BJT active load SPICE model parameters

texts: Why would Q3 and Q4 not have the same BF values in the picture of the Spice model i have attached?


texts: What is the bandwidth of an imaginary convolution?

texts:
I am trying to figure out the bandwidth of \$f_1f_2\$, where \$f_1 = sinc^2(3t)\$ and \$f_2 = sin(100t)\$. So when I take the Fourier Transform, I can rewrite the equation as such: \$F(\omega) \leftrightarrow F_1 * F_2\$. Easy so far.

Moving on, \$F_1 = 3\pi\Delta(\omega/12)\$, and \$F_2 = j\pi\delta(\omega+100) - j\pi\delta(\omega-100)\$. This is where I get stuck.

When you convolve anything with \$\delta(t+\tau)\$, it is merely placing the function you are convolving \$\delta(t+\tau)\$ with at time \$\tau\$. When taking bandwidths of frequencies, I know you only look past time \$t=0\$.

At this point I need to find the bandwidth of the function \$-3j\pi\Delta(\frac{w-100}{12})\$. Without this being in the imaginary frequency domain, for \$\omega \geq 0\$ there would be no bandwidth (everything is zero or has a negative amplitude for that frequency). However, we are in the imaginary frequency domain, so what would the bandwidth of this filter be?

The graph of the transform is
fourier transform [sinc^2(3t)sin(100t)]

(also on wolfram-alpha)


texts: Why is my MCP4822 DAC not outputting 0 V?

texts:
As part of my MIDI to CV project I am using an MCP4822 (datasheet) two channel 12 bit DAC.

After much toil I have everything working as planned, except for the fact that even when initialised with values which should give an output of 0 V, the minimum I'm seeing at either \$V_{out}\$ is 0.56 V: that's half an octave I'm missing. Why is this happening?

    void loop() {
    mode = digitalRead (modePin);      // GET MODE
    if (mode != prevMode) {
    setVoltage (DAC1, 0, 1, 0);       // INITIALISE BOTH DAC CHANNELS FOLLOWING MODE SWITCH
    setVoltage (DAC1, 1, 1, 0);
    }
    prevMode = mode;
    mode ? mode1() : mode2();

    }
    ................

    void setVoltage(int dacpin, bool channel, bool gain, unsigned int mV)
    {
    unsigned int command = channel ? 0x9000 : 0x1000;

    command |= gain ? 0x0000 : 0x2000;
    command |= (mV & 0x0FFF);

    SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));
    digitalWrite(dacpin,LOW);
    SPI.transfer(command>>8);
    SPI.transfer(command&0xFF);
    digitalWrite(dacpin,HIGH);
    SPI.endTransaction();
    }


texts: temperature Sensor error Resistor YSi400

texts:
I want to simulate the error resistor of a temperature sensor either Pt1000 or YSi400 and I am getting stuck at the point of how should I define this Resistor in LTspice. The value of the error Resistor is like in the flow diagram calculated and question is how can I set an error Resistor that changes value with the change of temperature. I want two different values of the error Resistor one for 40°C and one for 1°C.

If the question of what an Error Resistor can be is that I am trying to simulate the problem when we have a leak contact of the conectors or cables and the temperature will be some grade Celcius more than it really is.

I hope you understand the question and have an asnwer for me.

kind regards

Felix

gur.com/71OfQ.png


texts:
Please show me the steps to calculate current going through R1, R2 and D1 Led (Green color LED), when I tested this circuit through a multimeter it showed as 2.5ma across R1 and R2 but 0ma across D1, and also the voltage drop across D1 was 0.5 Volts.

Any way I can calculate these manually?.

simulate this circuit – Schematic created using CircuitLab


texts:
I have recently been reading about VHF switch mode power supplies and one thing that I haven't been able to figure out is what really is the point of resonant rectification. I could understand the point from the load matching point of view i.e. the rectifier needs to look like a certain load in order for the resonant inverter to stay in the intended resonance. I also understand the benefit that is got from ZVS if the rectifier is implemented using transistors i.e. synchronous rectification. However, what puzzles me is that I see lots of mentions about ZVS of schottky diodes and that makes absolutely no sense to me.

For example this paper Low Power Very High Frequency Switch-Mode
Power Supply With 50 V Input and 5 V Output has the following sentence: "Just as the MOSFET has an output
capacitance, the diode has a junction capacitance. In order not
to dissipate this energy in the diode, it is important that the
transition is made smoothly, so the capacitance is discharged
before the diode turns on." What is the other option? Turn the diode on before it's junction capacitance has been discharged? How could you possibly do that? This point has been made in lots of other sources too i.e. this slide lists "The diode turn off at zero voltage" as a property of resonant rectifier. Because of this I am a bit unsure if I understand the whole concept at all or not.

To sum up I am interested if I have got the benefits of resonant rectification right and also I would like to know what is meant by ZVS in the context of schottky diodes or any diode for that matter.


texts: Finding the capacity of a battery with its discharge curve

texts:
I have a couple of LiPo batteries, and I want to find how much capacity they hold (in watt-hours). If I monitor how it discharges, and how slowly the voltage decreases, and how much current is being used, I assume I could get an approximate discharge curve for that battery.
(The load I'm using IS NOT A CONSTANT CURRENT LOAD.)

Is there any way to find out the capacity of the batteries with its discharge curve?

Are there any better ways to find capacity of a battery, WITHOUT USING A CONSTANT CURRENT LOAD?


texts:
While I can measure line voltage safely, I need to write a procedure to have someone else measure the voltage. The load is pure resistive,and I want to measure the voltage across it, with a battery powered DMM.

While my main idea was to place a transformer to isolate the measurement and lower the voltage being measured, I did not want to add the inductance of the transformer to the load..

The only components that can be touched from the outside are two 2mm banana jacks. My question is, would it be safe to just to drop the voltage into the banana jacks via  3 high ohm resistor divider to measure 200Vac (line to line).

The main issue I see is if one of the resistors somehow shorts out, and a person grabs the DMM lead by the metal inserts into the jack.


texts: Multimeter input impedance and its effect on the measurement of charged capacitor's voltage?

texts:
while experimenting with capacitors, I charged a 15pF cap through a resistor to the voltage of a 1.5v battery. Then when I disconnected the capacitor and tried to measure its voltage with a 10Mohm input impedance multimeter, I found out, to my surprise, that the capacitor voltage (after being charged) is still zero!

Well, to tell whether this a multimeter or a capacitor error, I tried a different capacitor with the same value, and the result is still the same. Then I thought perhaps the capacitor is discharging through the multimeter input impedance, and that's exactly the reason why its effect becomes so strong when measuring low pF caps compared to the usual uF caps, because with low pF values the time constant of the discharging process becomes so small that the voltage reading of the multimeter goes to zero almost instantly.

So, I googled it and found out that actual capacitors discharge through the multimeter input impedance. The reason that I didn't know about it earlier, is because I used to test uF caps, so the voltage seemed almost constant to me.

My question is : How could I slow down the discharging process, when measuring low pF caps, such that I could capture it on the meter screen, without buying a higher input impedance meter?


texts: LtSpice: how to make a periodic PWL source?


texts: How do you run a 5v MCU circuit on a 12v car battery?

texts:
My Archery club has asked me to design and build a Traffic Light system for shooting, but they want it to run on a 12v car battery as this is what our previous system ran on.

I'm going to make the system using the pic18f4550 as the controller, so it can have an automatic mode as well as a manual mode, but this must run at no more then 5.5v. So I was going to use this 5v regulator circuit:http://thedasdet.deviantart.com/art/5v-Regulator-358912063

I'm worried that the 12v car battery will supply to much current and blow the regulator. If so  what can I do to prevent this?


texts: RC time constant - theory vs practice (simulation)

texts:
Time constant formula is

T = R * C

I need to create a delay of about 10ms so with a resistance of 3300 ohms I calculate that I'd need about 3.3uF capacitance in order to achieve that.

I simulated this circuit to find out that I'm only creating a delay of about 3ms. Why is that difference?


texts: Is it possible to power an AC light bulb with DC voltage, if not then why?

texts:
I have a GreenLux E27 7W light bulb (AC 100-240V, 60 Hz) and tried to get a minimal light output
from it by connecting ~2.40V 2 series connected AAA batteries. The bulb consumed ~60 mV (voltage dropped to ~1.80V) in several seconds and did nothing.
I was also told at the store that it is impossible to power an AC light bulb with DC batteries,
even if I would not bother to series connect dozens of 1.5-3V batteries and may not need the full 7W output.
So am curious why so, if power (in Watts) = V*I, so is directly proportional to voltage.


texts: So im trying to solve the folowing circuit using mesh analysis but i cant get the right results.Im trying to find the currents of mesh 4(down to the right) and mesh 1(left on the upperside).Ive determined that the current on mesh 3(lower on the left) is 10mA but i cant get the other results to be correct.Any help would be apreciated.


texts: Can anyone explain me how the voltage divider network works?

texts:
Can anyone explain me why the voltage of the red circle is 1.85V?

I know how the 25k-25k divider works but just don't know how the +5V-200k network affects the result.


texts:
I have been trying to work with ADC using ARM 7 LPC 2119  in burst mode however this functionality is not working.

My code is as follows:

    ADCR = 0X0121090F; // Start A/D Conversion

    //Wait for the conversion to complete
    while(!(ADDR & 0x80000000));
    {....}

I am also scanning 4 channels from AIN0 to AIN3, however on debugging I see nothing:

As can be seen, the ADDR value does not change when there is an input to AIN0. What am I doing wrong here? Any help would be appreciated.


texts: Need help with 90vdc PM motor speed control circuit

texts:
I recently found a Permanent Magnet 90vdc motor, 2.5hp, 18Amps. It has simply two wires for voltage (red/black) and two for thermal breaker circuit i believe (blue/blue). It came out of an old treadmill, and was run with an MC-60 motor control board. The problem is, the controller is shot and I really don't feel like wasting a ton of time analyzing what could be wrong with that old circuit being that I don't have the equipment here at home.

My Intent:

To build as simple of a control circuit as possible, giving me basic on/off and a fair amount of speed control. Once I have the speed control I'm looking for I'm going to gear it down to provide a more consistent speed/torque to drive a pottery wheel. If I have to I might get into the whole op-amp/servo-loop for consistent speeds but hoping gearing and flywheel will help with possible speed changes due to weight/load.

Can I use something as simple as the simple 555/mosfet circuit below, obviously scaling up the bridge and mosfet to handle ~30-40 amps or so?

Or should I try to isolate the power supply circuitry from the original circuit, and drive it through the opto via something like my netduino? Thus eliminating all the SoftStart/CurrentLimit/Signal circuitry that is just not necessary to me at this point.

I'd love to hear any criticism/references/possible solutions.

Before you worry too much about giving advice, I do have a good amount of experience with both AC mains and digital electronics. I was a carpenter wiring breaker boxes for 5 years, and now currently build/repair circuits. Where I'm coming short is understanding how to safely connect/isolate the two and drive such a large motor. I've handled smaller ~12v motors but nothing like this. Plus I'm actually testing all of my circuits digitally via MultiSim prior to actually building anything, because I know this isn't one of those "well lets see what this does" type of situations. I'd like to not fry my motor, and keep my eyebrows. :)

Thanks in advance!


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reference from here

why are there 2 exponential terms on right side of equation in red box ?

i know euler identity but why does  ,the left side  is trigonometry form when n=1  equal to exponential form n=1 + exponential form n=-1


texts: 74HC595 + ULN2003A not driving stepper motor

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Issue:

One of the stepper motors is not spinning.

Setup:

12V 10A power supply
arduino uno
28BYJ-48-5V stepper motor (27 ohm/winding)
74HC595
ULN2003A

The setup involves two stepper motor, as shown in the diagram. When powering up the circuit, only one stepper motor is turning. However, I can feel vibrations in both the motors. Furthermore, the motor that is moving does not actually complete one full revolution (I've coded it to turn one full revolution).

( There're some mistakes in the drawing: MR is connected to 5V, and OE is to GND. )

Troubleshooting:

Removing one motor would make the issue go away.
Connecting the ULN2003A directly to the arduino pins, instead of using 74HC595 helps too.
Using 28BYJ-48-12V (93 ohm/winding) helps too.

My current setup is actually ten 28BYJ-48-12V steppers, and they work fine for sometime before this same issue occur (one of the motor was not rotating). It seems that increasing the delay between each set of shifting helps too.

Update

I tried again with two 5V motors, and it seems that this issue did not occur again. However, I did a bit of testing:

Ten 12V stepper motors with 74HC595 (no issue with motor not spinning):

5V supply drops to 3.8V when all motor starts turning
removing each motor increased the voltage
Making all 74HC595 output pins HIGH caused supply to drop to 2.2V

I'm quite worried that the voltage supply is dropping when the input of a ULN2003 goes HIGH. My project will eventually involve 64 motors, hence I would imagine that the shift register will not get enough voltage to work properly.

Is this voltage drop normal? What should I do to rectify this issue?

Update 2

In case anyone is wondering, the problem appears to be due to my power connection to the arduino. The source of power for my arduino was initially from my laptop's USB port. After using a decent 5V power supply to power the arduino, the problem went away.


texts: The relation between Vin and Vout (diodes circuit)

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Can anyone here tell me if the function I found that relates the Vin to Vout is right?
So I made a mesh analysis to find the current in the first mesh (left to right) and in the second and got that the Vout = (2/11)*Vi +6.328
threshold voltage = 0.7V

that's how I did it:

IS IT RIGHT?


texts: I'm designing a power supply using a 7805 regulator and I need a very low output noise voltage at 1 Hz, hopefully around 1 mVpp. Will increasing the size of the output capacitor help me do this, or should I be adding additional circuitry?


texts: Generating a magnetic field with an electromagnet

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I want to generate an AC magnetic field.  However, when trying to do this with a ferrite rod electromagnet, the measured field strength (via magnetometer) was much lower than I expected.  I found out that the inductance of this electromagnet was also much lower than expected due to the large "air gap/path" of a rod's magnetic circuit:

Inductor core permeability much lower than expected

My primary goal however is not to achieve a certain inductance, but to generate a certain (AC) magnetic field strength with a coil loop and ferromagnetic core.  I figured the steps would be:

Given a desired field strength \$B_{min}\$ at a specified distance \$d_{max}\$, determine the necessary dipole moment \$m\$.
Given the permeability of a ferromagnetic material \$\mu_r\$ and its saturation flux density \$B_{sat}\$, determine the minimum volume \$V_{min}\$ of the material to achieve the desired \$m\$.
Determine the necessary combination of turns \$N\$ and current \$I\$ to achieve the desired local \$B\$-field (and thus \$m\$) given the chosen volume \$V\$.

Solving these in order:

Let's say I need a source dipole moment of \$m = .075Am^2\$ to generate the desired field.  This is half the strength of a small neodymium magnet: https://www.kjmagnetics.com/proddetail.asp?prod=ZD2.
To determine the minimum volume, let's say I want to bring the material to saturation (\$B_{loop,center} = B_{sat}\$)in order to achieve minimum volume.  In other words, I want \$V = V_{min}\$, and I will assume that the magnetic field generated by the coil is uniform everywhere in this small volume.

Assuming \$\mu_r\$ is large (e.g. >1000) and linear (even though this is usually not the case for ferromagnetic materials), we can say:

\$B = \mu_0(H + M) = \mu_0(H + (\mu_r-1)H)\$

\$\therefore B \approx \mu_0M\$

And because \$M = \frac{m}{V}\$, we have \$V = \frac{\mu_0}{B_{sat}}m\$.

For the 6.32mm diameter material with \$B_{sat} \approx .5T\$ referenced in my previous question, this results in a necessary volume of 377mm\$^3\$, or the rod with height 6mm.
Using the assumption of uniform \$B\$-field from the current loops to obtain a rough order of magnitude:

\$B_{loop,center} = \mu_0\mu_r\frac{NI}{2R}\$

Assume \$B_{loop,center} = B_{sat} = .5T\$, \$2R = 6.32\$mm, \$\mu_r = 2000\$ (type 77 ferrite)

This results in \$NI = 1.257A\$.  So for example, if \$N=100\$, then the necessary \$I\$ is 12.57mA.

However, despite having the electromagnet configuration described above, and at least a few mA of current, I measure an extremely weak field that essentially requires the coil to be right on top of the magnetometer to see anything.  Is there something wrong with my reasoning here?  Does it again have something to do with the air gap?


texts: Calculating Nmax in loaded bipolar junction transistor inverter

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I have tried various methods for calculating N max here, and some have resulted in negative answers while others have resulted in an answer of around 1.

Is my method correct? Or am I missing something in regard to what it means for Vo = Vol max?

The Question:

Equations that I used in my given attempt:

Attempt at part a:

I'm not sure if I should be including the forward current gain or the overdrive factor in my answer for part a. Are they acceptable as transistor parameters?

Attempt at parts b & c :


texts:
What is the correct way to write a 2 to 1 multiplexer truth table?

In a couple of tutorials I've come across (1,2), the table is presented as follows:

However, the same tutorials show the 4 to 1 multiplexor truth table as follows:

If this is the case, then why is the 2 to 1 truth table not the following?

I've also come across other tutorials(3,4,5) that show the 2 to 1 multiplexer as I would expect it to be (second case), and to me it seems the most consistent approach considering that all the larger multiplexers (n to 1) shown in the tutorials follow this pattern.


texts: How to modulate solenoid current driver with PWM?

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I'm trying to pilot solenoid valves in a hydraulic circuit.
I have two types of solenoids, one which support 2.4 A and another 1.8 A.

I pilot the valves opening using 120 Hz pwm and this driver.
It's on 8 V because of the 2.4 A solenoid that draw that much amp at 100% PWM.

In order to limit the current of the 1.8 A solenoid, I limit the PWM ratio.
It just works.

That said, does it exist a better circuit to drive solenoids?

I'd like to be able to limit current for each type of solenoid and drive them with PWM 0-100% from zero to max current.

I was thinking of current mirror circuit like this but using mosfet:

Screenshot of one solenoid datasheet:

And the opening vs current: I use 145psi delta

Are there any standard circuits for what I'm trying to achieve?

Solenoids have to be driven from source, not on the return to ground.


texts:
1 coulomb = charge of 6241509074460762607.776 protons(fixed amount of energy passing thru certain point).
So 1 volt = 1 joule(energy) per 1 coulomb.
and 2 volts = 2 joule(energy) per 1 coulomb.
does that mean that more volts literally mean packing more energy(joule) per fixed amount of charge(coulomb)? and how?


texts: LM2907 - Too many iterations without convergence - Proteus

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I am trying to use LM2907 to convert a frecuency signal into a voltage signal. The frequency signal comes from a motor encoder and it´s supposed to be connected to pin 1 from the LM2907, but I am getting an error that is coming from this connection, as it disappears when I leave the pin opened. I already changed the SPICE options from  Default to Settings for better convergence but I´m still getting the same error.
Here is the circuit I am trying to simulate , where Vpp is a 12 V rail and FV is the output of the LM2907

This is the error log:
[SPICE] Gmin step [61 of 120] failed: GMIN=2.76482e-007
[SPICE] Gmin stepping failed
[SPICE] Source step [0 of 120] failed: source factor =   0.0000
[SPICE] Too many iterations without convergence.
Real Time Simulation failed to start.


texts: Resources for learning how to implement an embedded programmer/debugger on my custom development board?

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I am in the process of designing a custom development board based on an STM32 microcontroller. This is all a learning process for me for embedded design, and one area that I know nearly nothing about is programming/debugging. I want my board to function similar to production development boards where the board is powered, programmed, and debugged through a micro USB port.

Powering the board with USB is simple; I've got that covered. However, I don't know where to begin with programming/debugging. I can't seem to find any resources on the subject matter that are simple enough for me to understand. So far I've learned that this is typically achieved by having a secondary microcontroller on the board flashed with firmware that handles programming and debugging. I figured I can use some open source firmware (e.g. Black Magic Probe) and flash that to a microcontroller, but I have no idea how I would physically interface this debugger microcontroller to the primary microcontroller on my board, or how to even use it.

I guess I'm asking for any recommended resources that may help shine some light on the basics of all this, or for any information that may give me a better understanding of how this all works. Essentially, my main goal is to be able to power the board with the micro USB, and to program it through USB without having to enter the bootloader by twiddling with jumper connections. Any information would be appreciated!


texts:
How can I implement a common sub-circuit which gets used in multiple places in a schematic with KiCAD 5,
so that when only one instance gets edited all the other places it appears are  automatically updated? Not by manually repeated copy/pasting.
Example:


texts:
I've been told that K-maps produce a completely simplified boolean equation, and they can't or shouldnt be simplified anymore after that. However, on allaboutcircuits.com they were able to simplify an equation more after the k-map. So what gives? Is this just an exception? Or is there something else I'm missing?

This is the k-map in question.

As you can see, D.a is simplified further after the k-map is done. It goes from AI + BI to (A+B)*I

For context, here's the full article. https://www.allaboutcircuits.com/textbook/digital/chpt-11/finite-state-machines/


texts: Understanding common-source amplifiers with resistive degeneration

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I understand that by introducing the series resistance to the NMOS in the amplifier circuit the gain becomes:
$$A_{v}=-\frac{R_D}{\left(\frac{1}{g_m}+R_s\right)}$$
Which means that higher values of \$R_{s}\$ correspond to lower gain, but perhaps this in return makes it more "linear". I can't quite comprehend what does linear gain mean, how does it make the amplifier better even though the gain goes down and how can I see that it was achieved by looking at the equation.


texts:
My son found one of these and he was curious what it was.

I showed him how to test it with a multimeter to show if it was blown and then proceeded to take it apart to show him the insides.

I expected to just find something similar to a glass fuse, but instead found lots of interesting things...

Sand of some sort
Fiberglass wrap (at least that's what my now prickly fingers say it was!)
A thin flat copper wire with a hole or two in it
A block of copper on a spring that appeared to be once soldered to a copper base

I have some ideas of what purpose each of these does, but I was hoping to get a larger idea of the design of these.  Is the flat copper wire also meant as redundancy for blowing the circuit? Is the soldered piece the primary? Why the hole?  How do they calibrate the solder release with the amperage?  What makes this fuse a time delay?


texts: Shared bus in FPGA (arbiter + perypherial bus) [VHDL]

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I am trying to implement shared bus in my fpga design. I am thinking about something similar to the microcontroller bus.

I see two possibilies:

Second option is easier to implement but if bus is wide it will be more resources used.
Something which is in my opinion optimal for my requirements is proposed in "Option 1". This approach requires three state buffers. Do you think it is achievable on FPGA ? Does anybody have some examples of code for design like this ??

Best regards,
Kamil


texts:
I've built this triac test circuit here:
https://320volt.com/en/triyak-tristor-test-devresi/

My transformer only delivers 10.5 V, however.

I've tested some triacs which seems to work well. Both LEDs light up when the button is pressed.

However, when releasing the button the LEDs turn off.

I've already reduced the load resistor from 470 Ohm to 100 Ohm to 10 Ohm hoping that this would make the triacs latch. This increases the current from 22 mA to 105 mA to 1 A.

I've double and tripple checked my circuit, everything seems to be fine.

The datasheet for the BTA16-800B states a holding current of 50 mA.

What could be the reason that the triacs don't latch even with a low load resistor?


texts:
I setup the following circuit:

When I measure the voltage between GND and INPUT of the LM7805CV I have a voltage of 7.9V (around 8V as per power supply). But when I measure the output it is only 1.4V instead of expected 5V.

How is this possible? I don't see why the voltage drops so badly.


texts: How to connect an AND gate with a shift register

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I'm new to using flip-flops, and making them into shift registers, but what I'm trying to do is turn on a logical AND gate based off the input of two flip-flops. The scenario is: first, a room light goes on, second a room light goes off, then an AND gate turns on. So what I'm doing is trying to build a shift register to recognize this sequence of events. When I turn the D input of the first flip-flop HIGH, the Q output of this is fed into the D input of the next flip-flop. When the first flip-flop then goes LOW, its Q(inverted) output is HIGH for the AND gate. So now both inputs to the AND gate are HIGH. So, by my calculations, it's like a "1" followed by a "0" fed through the shift-register. This should turn on the gate.

The results I get, however, are that while following these steps, the AND gate is turned on, but it's only for a flicker. I would have thought it would be turned on for the three seconds of the clock signal (the flip-flops are positive-edge triggered).

Is it that flip-flops can't use an analog sine wave for their clock? Or is it something else? I could be wrong, but watching my voltmeter, it seems like both flip-flops are getting set to HIGH simultaneously, rather than the second one waiting for the next positive edge to come along after the first. That would explain why the AND gate only stays open for a flicker. The bits are shifting through the register too quickly?

Hopefully I've explained the problem clearly. If not, I'll try to clarify.


texts: How to amplify a small AC (no DC offset) wave with an op-amp powered from a 0-5V rail and a pot-varying gain?

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I'm having a brain hiccup and can't figure this out. I've tried using simple summing amplifiers where I add my wave to an offset of 2.5V and then High-pass the offset.

However, I need to be able to vary the gain with a pot and in summin amplifiers circuits it seems like changing the gain on one of the inputs will also change the other one, moving the 2.5V offset I'm introducing to the system.

Is there a way to do what I'm trying to do with a single op-amp?


texts: I heard that if you come into contact with a high voltage DC current, you will ‘stick’ to it until it is switched off. Why is this and how high does the voltage have to be for someone to ‘stick’ to it?


texts: How to build cheap radio propagation beacon?

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I want to build a Radio Propagation Beacon but I would like to find an integrated circuit that does most or all of the work of the transmitter.

Transmit to 28Mhz (Ham 10-meter band)
Allow me to feed it Morse code audio and for it to transmit that.
As cheap and simple as possible, such as a single-chip solution.

I'll write some code on an Arduino to produce the Morse code. It doesn't have to be high power, 200mw range is perfectly fine.

I do have an radio amateur license.


texts:
I'm interested in how to properly realize Grounding in a CAN / RS 485 bus setup.
From my understanding, when non-isolated transceivers are used, in addition to the differential signal lines, a third ground wire should be used in order to eliminate potential differences between the nodes, that is, in order to avoid excess common-mode voltage at the transceivers' inputs.
In contrast, when isolated transceivers are used, no problems caused by different ground potentials will occur as the isolated nodes are floating.
My questions are:
1)
Is the above assumption valid?
2)
Assuming a CAN bus setup with only two transceivers: It is sufficient to just use one isolated transceiver while the other transceiver does not need to be isolated? From my understanding, this should be the case since no harmful potential differences may occur. Do I need the ground wire in such a setup?
3)
If my CAN bus has only isolated transceivers connected, is there any need to provide e.g. a high impedance ground connection at one transceiver in order to deal with static charging (or some other unexpected problem I am not think about)?
Many thanks in advance!


texts:
I have a data stream that looks like

x\xdam\xdd]\xc4\xeemZ\xc7q)2\xcc\xd6cL\x1a1\x8c\xc9hc\x0c)\xeb^\xaf\xd7Z (...)

How can I find out what I do see here? At the moment I'm trying to dive into binary, ascii, codec, utf-8 and so on but more in general. Hence, I would be grateful for every help that helps me focusing.

edit:
The data stream represents audio data that is allegedly given in a FLAC format.
But I can't tell if above data is already in FLAC or just binary encoded as FLAC or whatever.
Finally, my goal is very plain: To find out what exactly can be seen above. What is it or respectively in which format is it given?

It is audio data. Ok, but..

is it given in binary data
is the binary data given in ASCII?
is it FLAC but in binary form?
is it binary that has to be converted via ASCII into FLAC?
..

edit:
Here is the stream (I had to investigate where I can find the beginning..):

b'fLaC\x00\x00\x00"\x10\x00\x10\x00\x00\x03\xf5\x00\x07\xd9\x0b\xb8\x00\xf0\x00\x03\xa8\x00\t[\x92\x01*\xb7\xf2\xb5\xa0\xb7Ts\x89{\xce\x8a\x84\x00\x00( \x00\x00\x00reference libFLAC 1.3.2 20170101\x00\x00\x00\x00\xff\xf8\xca\x08\x00(H\xff\xfe\x00\x01\x00\x02\xff\xfd\xff\xff\xb5\xe7[\x1a\x1308\x0f0\x04\x95\xc8lA\x151\x9b'
(...)


texts: Mic preamp, fixing noise and gain issues

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I'm trying to fix a preamp (made by a colleague) that's noisy and somehow not amplifying enough.  I should say right away that this project is pushing the edge of my electronics knowledge so I have a lot of questions.  There's actually 2 copies on 2 boards, for one electret and one dynamic mics, but the design was the same except for the "plug-in power" for the electret (not phantom power, this expects about 5V, though I guess it's currently getting 12V).  This is the current circuit (only R3 is different between the 2 boards).

simulate this circuit – Schematic created using CircuitLab

From my research I found a few things maybe should be done differently.  First, it seems it's mostly power line noise that I'm getting.  (I tried getting cleaner power supplies but on a small budget that didn't work out.)  Instead, I could add some filtering on the voltage divider, and on the electret bias circuit.  I also don't like the idea of attenuating after amplifying so I'd move the potentiometer to control the gain instead, as such:

simulate this circuit

But these changes mean I have to pretty much redo the whole thing, and the product is in a "finished" state (in a box with connectors and everything), so I'd like to minimize the changes if possible.
1) (main question) I was wondering if "pre-filtering" the power supply would be equivalent/better/worse to having the filters in the preamp circuits?
I was thinking for example adding a 2nd order RC filter on a separate little board.  It would reduce the voltage a bit, but I can use small resistors and then do one good filter instead of 3?

The other issue is the gain.  Note that the goal is to get line level audio, so that voice from the mics is at comparable volume to other sounds coming from a computer.  The outputs goes to speakers (this is part of an intercom/mixer).  The gain is already at 2k and still pretty weak.  I'm thinking maybe the electret mic isn't getting the appropriate power?  I think it's supposed to get around 5V, but I read in another thread something I didn't quite understand about the electret inner workings and how the resistor value would change how much amplitude it would output.
2) Any tips on what value to use for the electret bias?
Note that the dynamic mic board (without R3) also sounds weak, but I'll have to verify, its R5 might have a different value.

Finally, I also read about resistor noise and how I'm better off not going too high (and use metal film) with such high gains.  But I'm not sure which resistors would be most critical.  In the second schematic, I'm guessing R8, R4... Not sure if the voltage divider also, R3, R9/11?  Related to that, I'm unsure what values to use for the voltage divider.
3) Other than not wasting too much power (prefer large values), or resistor noise (prefer low values), are there other factors to consider?
Note that the dynamic mic has output impedance of 600Ω but the electret, 5kΩ.
4) Should I "tune" the circuits differently, or just go with the highest one and give them about 50kΩ input impedance (R8)?

Any other comments or tips on the circuit would be appreciated!

5) In the second circuit, should the output after Cout be left "floating" or add a R to neutral, and if so what R value?


texts: Mount a capacitor on a connector without any solder

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I am looking for a specific connector that I can solder / press-fit in my PCB and mount a capacitor on the connector without any solder such that I can easily remove or replace the capacitor without desoldering.
I have one option to use a press-fit capacitor. But I am open to any other suggestion for the connectors.

AEC 100uF, with 2 leads, cylindrical, axial mouser.ca/datasheet/2/212/KEM_A4011_PEG124-1104316.pdf


texts:
I use the lt3471 to generate +/-9v for my portable headphone amp so i'm trying to make the voltage output as clean as possble and less affect to analog circuit. One of my concern in layouting this is how does the switching current go?

The converter operating at 1.2Mhz so i think the current switch at very high frequency, so the return current is right under the trace where current come in.
At the possitive converter (lower half), the first picture is what i thought when switch open: current flow from input capacitor (yellow trace), to inductor, charge Cout and then return from the gnd via of output capacitor (orange trace), go right under the yellow trace and back to input capacitor ground.
The second picture is when switch close: current flow from Cin to inductor then go back to the Cin's gnd through Gnd pin of the converter.
Am i correct? I can only post 2 picture so i can't post the schematic but it's exactly what's in the datasheet.


texts:
Can someone help me figure out what the little letters and numbers mean on the pins of this ic?

They're used throughout various ics in this iPhone 6 schematic. Are they indicating sequence?

For example A1 happens first then A2 etc or?

Sorry that it's showing up blurry. It's crystal clear on my phone. Not sure why it's compressed like that


texts:
I have some question almost uncorrelated, so I'll enureamted it, hope you can help me:

1) I'm studing RTL Design, and the question is at level of data path, arithmetic unit ecc. I don't understand why and how a shifter can be used to do the multiplication and division operation. For example, if someone ask me "how many adder (or shifter) is needed to do a multiplication between to operand composed by X bit", what is the method that I have to apply to answer this question?
Another question. In a book I've read that the operation A+B=K, in wich the output is 1 if the sum of A and B is egual to K, 0 otherwise, can be performed evaluting the Carry expected and Carry obtained by summation. I didn't understand this concept, can you please explain me?

2) VHDL. This question is simple, I think. In all example in the books, when a flip-flop is present, the rising edge of the clock is managed in this way: process(clk), and then for expalin the rising edge there is a line "if(clk'event & clk = 1)". The question si: why "clk'event" is necessary? The signal clk is inside the process, so we go inside the process each time the clock change its state, isn't sufficient to evalute only if clock is egual to 1, because the clk'event is Always true?

Thank you


texts: Difference between RTL and Behavioral verilog

texts: Can someone tell me what is the difference between RTL and behavioral Verilog code? Is there any clear cut demarcation between designs at these two levels?


texts: RF sampling ADCs(ADC12DJ3200 ),PLLS and regulators placement and layout

texts:
I am novice in PCB component placement and layout. I have just started my career in Hardware design.

We have designed a schematic for Data Acquisition System.

In our design, we are using three RF sampling ADCs (ADC12DJ3200) from TI.

ADC12DJ3200 is a Dual Channel ADC. Sampling rate for this ADC can go upto 6.4GSPS in single channel mode.

Maximum supported sampling clock is 3.2GHz.

ADC12DJ3200 supports JESD204B standard. One ADC has 16 differential lanes ,so for our design there will be total 48 differential lanes.

Data rate for one lane can go upto 12.8Gbps however as the no. of lane increases, data rate will decrease per lane.

According to JESD204B, two clocks are required for each ADC. One is DEVICE clock and other is SYSREF.

For generating and distributing necessary clocks, we are using two PLL ICs from TI , LMK04828 and LMX2582 and one buffer IC from Analog Devices HMC987.

Clocking block diagram and flow is shown below:

ADC12DJ3200 required two different voltages for its operation: 1.9v and 1.1v.

For powering all these PLL ICs and ADCs we are using total 11 Nos. of regulators out of which three are switching regulators and remaining 8 Nos. are LDOs. We are using separate LDOs for each ADC12DJ3200.

Our planned board dimensions are 190mm*186mm right now.

We are planning to use Megtron 6 material for our PCB.

Below is the image of our board right now:

Position of SMA connectors is not fixed. If we get some useful suggestions for placement of SMA connectors used for ADCs and other signals, we will change the position of SMA connectors.

We need to keep the FMC+ connector on the top right side of the board because of our design requirements.

Now for placement of all the componets on board, we tried to take reference from TI Eval Board for ADC12DJ3200.

But TI Eval Board uses only one ADC(we are using three in our design) and also they have placed the FMC+ connector in the middle of the PCB.
 So they have used left side of FMC+ connector for power and right side for Clocking and all the 16 differential output signals from ADC is routed through the middle section of the PCB and no component is placed above the area through which traces are running from ADC to FMC+ connector.

TI Eval Board’s divided sections are shown below:

Now, as in our board the FMC+ connector is on the top left of PCB and also we have 48 differential output pairs for three ADCs,  which right now we are planning to route through left side of the PCB from three ADCs to FMC+ connector.

And if we also don’t use the area below which high speed JESD outputs of ADCs are running from ADCs to FMC+ connector, we need to use the right side of our board for placing both the clocking section and power section.

Can we place both power and clocking on the same side of PCB without interference?

It will be of great help if someone can guide us where to place the clocking components(LMK,LMX and HMC), three ADCs, switching regulators and LDOs.

Also if all the power and clocking ICs, cannot be placed on the right side of PCB due to lack of space availability ,can we place some components on the area below which high speed differential outputs of ADCs are running from ADCs to FMC+ connector?

Also as these ADCs are direct RF sampling ADCs, we will be testing these ADCs for input signal upto 10GHz.

Right now the spacing between one Channel of ADC to other channel is 20mm.
Is this enough for our application to keep the cross talk minimum from one channel to other channel.

If it seems like more information is required for this, then please let me know.

I have read here only (EE.SE) that if placement is done right, then more than half of the layout is done.

So, please guide us so that we can make our design successful.

Edit 1: We are planning to use signle ground for all the components.That is right now we will not divide the ground planes in AGND,PGND or DGND. If someone can guide us for grounding scheme(like whether single ground plane is ok or dividing the ground in AGND,PGND or DGND required) also it will be most welcome.


texts: What will the output of filp-flop if its input is metastable?

texts:
I was reading sunburst paper on Clock Domain Crossing and got stuck with this doubt.

Here in the 3rd flip flop, input is metastable state but at the rising edge of the clock output was set to high. In box they mentioned "clocked signal is initially metastable but sampled high on the next active clock edge" but no were in the document they are mentioning its reason. Please help me with this problem.


texts: Analog signal multiplexing with digital control

texts:
I need to route one of several analog signals to a single ADC input, using digital control signals. I have done this in the past using the 4051 multiplexer IC (or the more modern 74HC4051), but this time the signals are high frequency (about 100MHz) and should not be distorted or attenuated by the multiplexer. However, I have no idea on the bandwidth of a regular 4051 or 74HC4051, the datasheets I have found don't have this information.

What kind of parameter should I look for on the datasheet to understand the analog bandwidth of such a multiplexer?


texts:
I am trying to synthesize this VHDL code and it won't do it -- Why ?
...if( v(0) = '1' AND o_done = '1' ) then....
it complains about o_done ?
Read error: trying to read port of mode OUT
What can I do ?
This is legal in VHDL-2008 (reading output ports) but I think Synopsys Design Compiler won't accept it - why is that ?


texts: Poles and Zeros of Two Pole Compensation

texts:
I am known with the basics of what poles and zeros of transfer function are and how to determine them, but I certainly don't know how to apply such poles and zeros to the gain curve, which describes frequency response of an amplifier. Also, this video explains the basics of poles and zeros, and I understand it completely.

This is the picture of Bode plot of an amplifier from some research paper that can be downloaded here:

The steeper curve shows two pole compensation frequency response, while the other one is for dominant pole/ single pole compensation of an amplifier. With the red dot I marked a pole, with green mark I marked a zero (which are located there, accordingly to that research paper).
The pole is defined as the point in an imaginary plane to which function approaches.

How can the red dot be a pole according to the upper definition of it? Zero is defined as the point in a real plane in which transfer function that is being observed reaches value of zero. According to this research paper, the zero of two pole compensation is located at 320 kHz (that is somehow close to green mark).

How can according to upper definition of zero a zero be located, where the curve is marked with green dot? I would say that a zero is located at the frequency where a both functions "cross" 0 dB of gain.


texts:
I'm trying to connect a power meter (http://www.ebay.co.uk/itm/272572704122)  with Modbus over a RS485-USB converter (http://www.ebay.co.uk/itm/231570466384)

The converter looks like a serial port (/dev/ttyUSB01 or COM5).

Just a cable A-A, B-B, both converter and meter just have two pins.

I have set the right speed, 2400 baud as the meter shows on the display, but I just get time out, either on Raspberry Pi or on two different USB scanners.

Am I missing something?

EDIT

I finally got it working.
I was playingdeveloping with a 3-phase meter, but on my workbench I only have one phase, so I connected it to phase L1, and the display went on nicely. However, the modbus only works if the meter have power on L2, not L1 or L3.

Also, the only register is the accumulated power, which is hidden at 0x011e, which my scanner were not testing; I/it presumed the registers were starting at 0 or 1.

I also added a 150Ω resistor at each end, if it didn't help for the signals, at least it helped getting the flimsy wires of my phone cable into the connectors; I soldered the wires onto the resistor ;-)


texts:
I plan on connecting 8 LEDs in parallel with 3 AA alkaline batteries (i.e. 4.5 volts) being the power source, and only one 230 Ohm resistor.  The circuit is really simple/generic, so I assume no schematic is needed.  The issue that I'm facing is that the more LEDs I add in parallel to the circuit, the dimmer the rest of the LEDs become.  This is the kind of behavior one would expect if the LEDs we're connected in series, so I am a bit lost.  It would also be worth mentioning that I also tried using a battery pack (the ones for phones) with an output current of 2A, but the results were the same.

Thanks for the help!


texts: How to determine lock time of PLL/VCO vs frequency change?

texts:
I am trying to build a transceiver for a stepped-frequency radar. As a starting point, I am trying to generate my signal on NI's AWR VSS software. I am able to generate my signal but don't know what should be the step time for changing one frequency to another.

I know that higher the step size longer the lock time. But How should I read the commercially available PLL frequency synthesizer datasheet to find out the information and can generate my stepped frequency vectors?


texts:
I want to set up an electronic work area. I'm worried about ESD etc. I'm confused why some aspects of ESD precautions require high resistance to ground (1 Megohm for wrist straps) and others need to be low (milliohms marketed for the soldering iron).

I know the wristband should have higher impedance to reduce the chance of electric shock, but I don't see why such a low resistance is desirable for the soldering iron, if the goal is an equipotential. Yes, when charge is suddenly introduced that needs to be dissipated to ground, a higher resistance means a higher voltage. But since static is likely to be generated by a person, and the wrist strap needs such a high resistance, then the resistance of the soldering iron is immaterial if it is already many magnitudes smaller.

The only reason I can surmise is the iron's earth is less for ESD and more just electrical safety, eg if there's a live fault, so current will surge to earth and fuse will quickly blow. This has then been mis-marketed as an ESD feature.

End then there are ESD mats, where the top layer is "dissipative", i.e. not an insulator but pretty dawned close, (gigohms?), magnitudes greater than the wristband. Why?

What's the reason for differences?


texts: Why comparison of biased representation are faster than two's complement?

texts:
Biased representation (or excess-N, offset binary) are used for floating number representation in computers. This wiki page says

  This allows high speed comparisons

Could any one explain why comparison is faster (potentially in terms of gates implementation)?


texts:
What is this cable called?
I need to extend it with a male to female cable.


texts: Why flow of real power depends on the phase difference of voltage magnitudes?

texts:
Let's say that we have a generator and a RLC circuit. Real and reactive power are tranferred at this system.

Transfer of real power depends on the phase difference between the voltage of the generator and the voltage of the load and transfer of reactive power depends on the difference between the magnitudes of these two voltages( maximum voltage of generator minus maximum voltage of load).

Why is this difference? I thought that more intuitive is the real power to depend on the difference of magnitudes.