texts: I2C with DS1307 hang after end of transmission

texts:
I've got a home brewed RTC with DS1307. I've put two pullup resistors on SDA and SCL lines, connected them to the Arduino 5 and 6 pin respectively. I've also provided a backup battery since I read sometimes the RTC can hang if there is not a proper backup voltage.
The arduino program hangs on the instruction:

int err = Wire.endTransmission();

I guess there is no reply from the device so SW wait indefinitely.
Strangely if I remove the I2C conenctions, endOfTrasmission returns a NACK error code ( I say strangely because I better expect an hang without any device connected ).
I have no idea on what to test, I suspect the DS1307 being damaged by some adventurous test in swapping A5-A6 data but I have no idea of how to make this diagnosis.


texts: Troubles on powering two (audio) circuits with single voltage source

texts:
I have a simple audio circuit that needs to be amplified.
The circuit is a CMOS based circuit, running on 9V coming from a 12V battery pack stabilized with a 7809 IC. I have also an amplifier circuit based on the Texas Instruments LM4950. The circuits are on separate PCBs.
I'd like to power the amplifier with the same voltage source as the audio circuit (the 12V battery pack.)
Now my problem is: when the circuits are powered with two different sources (two 12V battery packs) all is fine and the amplifier circuit sounds perfectly. When I connect it to the same battery pack (directly to the 12V) of the audio generator circuit it sends out only loud, interrupted noise.
I tried to opto-isolate the amplifier voltage source to eliminate the distortion and to filter the voltage with capacitors but it does not work. I also measured current to check if the current absorption of the amplifier is too high for both circuits but I measured only about 100 mA.
Maybe is a silly thing but I really can't find out to resolve it, hope that someone can help me.
CMOS Sound circuit

Amplifier circuit (straight from datasheet)

Connections diagram


texts:
Does anyone know of any old-school function generator ICs (similar to the ICL8038 or XR2206) that are still on the market? (i.e. not obsolete / NFFD - I'm not interested in scouring the globe for old inventory)

I'm aware of digitally-programmable parts that use I2C / SPI, but am looking for something that won't involve adding a micro to a legacy design.

I'm looking primarily for an IC that will output a triangular waveform at low frequency (640Hz). The XR2206 was the original part in the application which is now obsolete. The frequency can be adjusted a small amount from an external input (+/- 50Hz or so).

Exar has obsoleted most (all?) of their function generator parts:

update:
The product has passed into obsolescence and the assigned engineer is no longer with the company. The question is now moot.


texts: Audio Circuit to Remove Vibrato while Preserving Word Detail

texts:
In music, vibrato describes the warble effect often added in by singers as they sing. I was trying to come up with a circuit to remove it from an  audio signal, almost like a "vocal stabilizer" leaving only the pure vocals and I'm a bit stuck. My first thought was that there are a few characteristics of vibrato that differentiate it from the rest of the signal. Most of my knowledge of audio circuitry is self-taught, so please excuse my lack of proper terminology. Vibrato tends to be:

One relatively-regular low frequency (~2-20Hz) overlaid upon the existing "note frequency" (the 80Hz-15kHz normal range of human voice determining note in the music)
Oscillation of both amplitude and frequency, sharing the same interval. I.e. in vibrato both the volume and note go up and down simultaneously, at that same 2-20Hz
Infrequent, only appearing on certain parts of the signal (by time)

It would seem based on these three characteristics that vibrato is definitely differentiable, it's just difficult to extract without removing other detail. Any ideas?


texts: How do I power a ATmega328 with a coin cell battery

texts:
Ok, so i am really keen to try replicate this project here

I'm still a noob and my knowledge of electronics stretch as far as making a light blink using an Arduino (Maybe a bit more).

I was thinking of using a ATmega328 instead of the ATtiny24A, because I can program it using my Arduino Uno like explained here

So this leads me to my question, how do I use coin cell batteries to power the ATmega328, maybe more specifically, what components will I need and why?


texts: Can I power this LED circuit from 5V USB powerbank?

texts:
I have an old flashlight that says "15W Police Waterproof" on the handle, the battery compartment is normally for 3 type C batteries, unfortunately the bottom battery leaked and is stuck in there. Would it be possible to power this up from a 5V USB powerbank?

I don't want to burn the LED, is the driver more voltage-tolerant than the LED and will accept the higher voltage?

What has got my attention mostly is the note "AAA*3/AAA*4". - does it mean it can operate between 4.5-6 Volts?

PS: If you were going through the circuit, it might be helpful to know that the flashlight has 3 modes that cycle with power button - bright-dimm-strobe.
PS2: The whole powerbank (image below) fits in the compartment.
Note: I don't trust the 15W label as I have not found a single 15W LED on the internet.

Click an image for high-res.

Search tags: HT-4.5S/1 , B17332A

/edit

So I have tried to power it:

The cheap powerbank immediately shuts down (and needs a reset by connecting a charger) as the output is too high. Such a shame. I guess I can't have nice things.
It draws 5.06V @ 0.23A (1.2W) at low mode
It draws 5.26V @ 1.94A (10.2W) at high (my source is limited to 2A per port)
I will try it with a Y cable.
See compared High mode with 5W source and 10W source:

Also included is the back side of PCB, the power switch is inserted between the central piece and positive source. Negative source is connected to the casing.

The flashlight is indeed around 10 years old.


texts:
Especially passives like resistors and capacitors.

It looks like the E12 series is still the most used for resistor values, despite that it only covers the full range for 10% tolerance. It looks like 10% is hardly used anymore.

What precision for resistors do you normally use, and why? Do you always use the same tolerance, or for which applications would it be different? Same for ceramic capacitors (I realise that electrolytics are a completely different story).


texts: The term `frequency' in EE (especially signal theory)

texts:
In physics, frequency is simply \$f\$.

I mean,
Frequency: \$f\$ (with unit Hz = s-1)
Angular frequency: \$\omega = 2\pi f\$ (with unit rad/s)

However, when I read EE textbooks, they use `frequency' for both of them.

For example, when they say something like RF, they use frequency in Hz ― so \$f\$.
However, in textbook Signals & Systems 2th Ed. by A. V. Oppenheim et al,
they introduce fundamental frequency as \$\omega_0 = 2 \pi f_0\$.
When I try to solve problems like `find the frequency' without any appearance of \$f\$, \$\omega\$, or units, this drives me crazy.

How to differentiate them? Only by the context? I hope not...


texts: For anyone familiar with interscatter technology: Can a single device (smartphone) be used to generate the bluetooth packet and receive the wi-fi signal? From the paper it looks like you need a separate bluetooth generating (e.g. smartwatch) and wi-fi receiving device (e.g. smartphone). Cheers!


texts: Can I use single phase 220v AC to power a rectifier designed for 3 phase AC?

texts: I want to use a use a rectifier (Eltek Aeon SMPS 4000 Rectifier, used in telecom) as a stand alone DC power supply (puts out 24v/125a).  The unit was designed for 3 phase 220v AC input.  I have only single phase.  Is the unit likely to function on single phase?  If so, would there be any performance loss on single phase vs 3 phase input?


texts:
We are using an Advantech PCM-3363 PC104 board to drive a NLT Technologies NL10276BC13-01C LVDS Display in an embedded device.
While everything works fine usually, the display sometimes is corrupt.

This screen is the usual "Windows did not shut down correctly" screen, normally colored light grey on black. The horizontal lines are an artifact caused by my cheap smartphone camera.

This is what we observed:

The problem is rare, but if it happens, it tends to happen a few times in a row. After each time, we power down the device completely.
Most of the time, it happens when switching to, or in, a resolution that is not native to the display (The windows start logo displays att 800x600 always). The bios boot-up screen was never affected.
We used different display drivers and operating systems, and got the problem in every case after a while.
We can observe this problem with two identical devices.
A monitor plugged into the boards VGA port does not show this problem.

What steps can we take to troubleshoot this problem and what may be causing it?

I hope that this is the right place for this question; it seemed a better fit than the other stackexchange sites.

Please ask if you need additional information.


texts: I cant interpret what this question means. Can anyone help me answer it. Thanks in advance


texts: How can I switch on 12V 500mA supply to a load when a signal is taken from 5V down to ground?

texts:
I have a commercial PCB. On it is an IC with a pin that is pulled down to ground by a normally open switch. I want to turn on supply to a load when the switch is closed.

simulate this circuit – Schematic created using CircuitLab
It's not possible to modify the switch as it is in a sealed unit. I can only tap into the cable between the pin and the switch. The cable between the switch and ground is common to 2 other switches which take their respective pins low when closed.
The pin is high at 5V. Battery is a 3S lipo. The load consumes 560 mA at 12V. The load is a set of LEDs, with some circuitry to regulate power and provide some protection.
I don't have any information about the IC, as it is an unlabeled 8 pin package. I measured 1.2 mA between the pin and ground when the switch is closed. The IC is supplied 5V, regulated from the same 12V source.
I want to attach something between the pin and switch that will turn the supply of power to the load, when the switch is closed and the pin is taken low.
I gather I need a P-Channel enhancement mode MOSFET here. Is this appropriate? If the power supply was a constant 12V, then a Vgss of -7V to -12V would be good, however the supply voltage may dip a few volts when the switch is closed. I'm struggling to measure how low, it might be as low as 6V. What components should be placed around the MOSFET to support and protect it?


texts:
(Pardon me if this is not the best place for such question. I searched a bit but no better place found.)

I learned both assembly language and basic digital circuit design back in college. But after so many years of coding with various languages, I think I still miss the critical knowledge in the middle of those 2 parts:

  How does high-level assembly instruction get translated into low-level
  logical gate behaviors?

AFAIK, the lowest level of a computer is various logical gates. For an assembly language instruction such as movl 10, eax, I know it will be translated by an assembler into a sequence of 1/0s. But how is that translated into actions of logical gates? And I heard there is so-called micro-code for processors. How is that related?

ADD 1

Thanks to EugeneSh. Below are some useful references:

Nand2Tetris:

Official site: http://www.nand2tetris.org/
Coursera: https://www.coursera.org/learn/build-a-computer
The book: http://www.amazon.com/Elements-Computing-Systems-Building-Principles/dp/0262640686/ref=ed_oe_p
Course lecture materials & ebook: http://www1.idc.ac.il/tecs/plan.html
TED talk: https://www.ted.com/talks/shimon_schocken_the_self_organizing_computer_course


texts: Is it clever to put the AGND ground pour ONLY on the bottom layer and the DGND ground pour ONLY on top layer?

texts:
In an audio system, I am reading samples from an sd card and sending those back to a 16 bits DAC for audio playback.

My prototype works but is too noisy. I discovered than using 2 separate Vcc/3.3V (provided thus by 2 different regulators) is helping quite a bit. So the MCU and Micro sd card are powered by regulator 1, and the DAC by regulator 2. I also separated physically on the board the analog from the digital circuitry.

The last thing I want to do, is to use 2 ground AGND and DGND.

The question is : If I can afford it "spacewise", is it a clever idea to use a top ground pour as the DGND and the bottom ground pour as AGND ? They would rejoin only at the power entry connector.


texts: Midi input that doubles as gate voltage input

texts:
I'm building something that would benefit from a midi-clock input, but also a analog clock input. In order to save space, i'd like to use a mini-jack with an adapter for the midi cable (as seen in the Arturia Beatstep pro for example) and have it double as a analog clock / gate input.

Seeing some synths have gate signals that go up to +15v, I'd need some protection in order not to fry the opto-coupler mandated by the midi input.
A simple resistor in front of the ir-led won't do the trick: the forward current will either be too low in midi-mode, or too high in +15v gate mode.

I guess the capacitance of a zener prevents me from using that as voltage protection, because it will be too slow for the midi signal. Maybe there is some other thing I overlooked?


texts: How to access generated instances systemverilog and Vivado 2014.1?

texts:
I generate instanced using the following code:

I try to access them like that:
R[0].router3d.address= 0 ; // for example

The simulation went fine But the code is not synthesizable with the following error:
Cannot resolve hierarchical name.

Any idea why ?


texts: Understand the shielding of a USB device

texts:
I have a GPS PCB which has regular USB pinouts (GND, +5V, DATA- and DATA+), but in addition has one stranded wire which is connected to USB type A plug. Marked as "USB connector" on the image:

What is the purpose of this stranded wire? If this is for shielding purposes, then why is it connected in both ends? Doesn't this create a "shielding loop"? In addition, if this matters, there is an aluminium-foil shielding around all five wires:

..and this aluminium-foil is also connected to USB plug, i.e. aluminium-foil and stranded wire are electrically connected.


texts: What is the intended usage of "WE" or "PE/OE" pins on 4517 shift register

texts:
The xx4517 (http://www.onsemi.com/pub_link/Collateral/MC14517B-D.PDF) is a 16-pin chip which contains two 64-bit shift register units, each of which in turn is divided into four 16-bit registers.  Each of the shift units has a pin which may be called "WE" or "PE/OE" which selects between two modes of operation.  In one mode, the bit 0 input is latched into the first register, and each of the other registers latches the output of its predecessor.  The outputs of all four shift registers are sent to device pins.  In the second mode, the drivers for all four outputs are disabled; the first three pins are repurposed so that the second through fourth shift registers will take data from them pins rather than from their predecessor shift registers.  The final output pin is simply unused.

It's clear how the device could be useful when the mode pin is strapped low.  I can also see how it would be useful to have a means of switching between either of the following pairs of modes:

Intermediate shift values are output and passed to the next stage
Pins are floated but shift-register outputs are passed to the next stage anyway

Pins are floated but shift-register outputs are passed to the next stage anyway
Pins are floated, and shift registers take input from them

I'm curious in what way the mode-function as it actually sits can be practically utilized.  In all the cases I can think of where I would sometimes want a device to load the middle taps from external pins, there would be times when I would want it not load middle taps from the external pins but not output anything to them either.

Since parts with the xx4517 pinout have been made for decades while some other kinds of shifter registers have come and gone, and since 14 pins seems to have been at least as common a size for discrete logic as 16 pins, it would seem curious if those pins were never used by any of the circuits where the part has been employed (especially since one can readily imagine other useful purposes to which such pins could have been put).  Is there some clever means of using the 4517's WE pin that I'm unaware of?  The only thing I can think of would be for applications which only want to use the mid-tap pins as inputs to drive them via 4.7K resistors, and ignore the fact that they'll often be back-driven, but that seems really really icky.  Were there better uses?


texts:
I have a multidrop RS485 network with one master (PC with RS232-RS485 converter) and 2 nodes using the Max13487 (schematic attached).
Communication is fine in both directions using one node. However I get nonsense(sending and receiving) when another node is added.
If I power down the micro on one of the nodes, the other will communicate fine.
This seems to be the case with and without termination resistors and biasing resistors.
The code is written so that either node will only respond if their ID is correct.
Do you have any advice on troubleshooting this problem?


texts:
first of all this is for an assignment so I have certain limitations, mainly cost. The problem I'm having is I have run out of PWM inputs on my ATtiny45 but I still want to drive a servo. The two PWM outputs are taken up driving two motors. This servo would only have to sweep from left to right and back smoothly constantly to allow me to take reading at different angles off a sensor attached to the arm.

Is there a way I can use a 555 timer to sweep a PWM signal to control the servo? My idea would be then to smooth out this PWM signal to read it as Analogue signal on one of the inputs of the ATtiny45, thus reading the angle. In reality this servo is doing something quite 'dumb' so shouldn't really need a micro controller driving it.

As I said, this is for an assignment so don't give me too much detail, but any pointers on this scheme or suggestions to give me more PWM capability would be greatly appreciated. :)


texts: Motor Driver IC - Motor Supply with Capacitor in Series

texts:
I'm trying to figure out what should be the voltage rating of the capacitor in series to VHS pin of TMC2660 driver. And also how is the voltage of the VHS pin is calculated for 24V motor supply voltage ?

"The Power Mosfet Stage" part of the datasheet states that

  The high-side gate driver voltage is supplied by the
  VS and the VHS pin. VHS is more negative than VS and allows opening the VS referenced high-side MOSFET. The high-side driver supplies VS to the P channel MOSFET gate to close the MOSFET and VHS to open it. The effective low-side gate voltage is roughly 5V; the effective high-side gate voltage is roughly 8V.

VHS pin(35.) connected in series capacitor and then the motor supply voltage(V+). The driver supports 8-30V supply voltage, so I'll consider giving 24V to motor supply. The circuit in the datasheet:

Thank you.


texts: Decreasing the surge power of the AC loads

texts:
I have a pure sine wave inverter 12v to 220v AC, its continues output power is 600VA and the surge power is 1130VA, I want to running my 200W fridge, but unfortunately my fridge surge power is a bit more than inverter surge power, its need to about 1300VA for a few seconds so when i run the fridge the inverter shut down.

I'm wondering if i can decrease the surge power of my fridge by using for example a dimmer(motor speed controller) just for the starting, or any other solutions for this problem?


texts: How Much Power do I need to give to these Servos?

texts:
I am building a robot to control a Wiimote Controller, or a Wii Classic Controller, as part of a larger machine learning project. I've found a set of parts that should work for my purposes. However, I've got little experience with electronics. I believe I've found parts that should work together just fine, but I don't know how much power I should put into this.

The Robot will be comprised of:

1 Polulu Micro Maestro 6-Channel USB Controller

6 Spektrum 2.9g Linear Long Throw Servos

1 Wooden Mounting Set

The Maestro Controller will be powered off my computer's USB Port, so it's not much of a concern. However, the servos cannot draw power from USB (The Controller doesn't support that option, and I don't think it can supply nearly enough even if it could).

I'm uncertain on how I need to setup the power supply for the Servos. I'm planning to do it with a battery if possible. I should be able to feed them straight through the Microcontroller... but I don't know what voltage the battery needs to supply. I also don't know if there are any secondary concerns I should think about.


texts: The function of a capacitor with the fluorescent lamp

texts: What is the function of the capacitor across the supply to the fluorescent lamp when it is used?


texts: generic and generic map | total time delay for each files

texts:
In adder.vhd

  H1: half_Adder generic map ( gate_delay => 6 ns );
  port map ( a => ln1, b => ln2, ... );

half_adder.vhd

  Ex1 : xor generic map ( gate_delay => gate_delay );
  A1  : and generic map ( gate_delay => gate_delay );

and.vhd

  entity and is generic ( gate_delay : Time := 2 ns );

xor.vhd

  entity xor is generic ( gate_delay : Time := 3 ns );

I gave four files.

My question is, how much should one wait to see correct result ? In other words, what is the total time delay for each file?


texts: connecting devices with two different power supplies

texts:
I wanted to know if this configuration is fine with two different grounds. the microcontroller is powered up with 3.3V and the transistor is powered by 5V. Both grounds are separate.

My question is whether it is safe to connect the microcontroller pin to the transistor to switch On/Off the motor?


texts: How do MPPT charge controllers curtail the power if the load is less than the solar generation?

texts:
I am trying to understand how MPPT charge controllers work when the load is less than the solar power generation. Let's assume an off-grid system with battery backup and no dump load. In my understanding, the following situations can happen:

solar < load: solar will partially fulfill load requirements, rest will come from the battery
solar = load: all of the load is fulfilled by the solar directly, battery status remains unchanged
solar > load (battery not fully charged): solar will power the load and rest will go to the battery.
solar > load (battery fully charged): In this case, the charge controllers curtail the power generation to match it exactly with the
load. The excess solar energy is lost in the form of heat.

I want to understand how this curtailment happens in actual MPPT charge controllers. Do the MPPT techniques/chips leave the MPPT mode and the operating point of the solar panel is controlled by the current drawn? In that scenario, how does this whole circuit (DC-DC converter) knows how much demand is out there? Is there any implicit feedback loop?

I will highly appreciate your detailed response on the question. Please let me know if the question is ambiguous.


texts:
I've encountered some problems while trying to get this scheme.
I don't think graph should look like this.
What I am trying is to draw a diagram to record the static characteristic of the Zener diode for
a) direct polarity
b) reverse polarity
c) both of these for temperatures -10, 20, 50, 80 and 110°C

Here is the diagram I got for direct polarity.
I used Analysis → DC Analysis → DC Transfer Characteristic
while setting V1's value from 0 to 1 V.
Two last images are from the similar example and everything worked well

I am a beginner (student) as you can see but willing to learn. Thank you for answers (if there'll be any)


texts:
When I do prototyping I solder my PCBs by hand. That works fine most of the time, but I run into a problem when I have to solder chips with fine pitch (Google for VQ100 to get an idea of what I'm working with). The problem is not the soldering by itself but keeping the parts in place once the pins are aligned to the pads.

Now I'm looking for an adhesive that lets me temporarily stick a large SMD component onto the board so it does not slip away as soon as I touch the pins with my soldering tip.

During a Google search I found a log of SMD adhesives, but all of them are resistant to PCB cleaning substances. I need the exact opposite. Something that lets me temporarily stick a part onto the PCB and dissolves fast in PCB cleaning chemicals (I use isopropyl alcohol if that matters).

Something with the sticky properties like thick honey would work except that I'm looking for a more professional solution.

I'm certainly not the first one to look into this, so there must be a ready made product out there, right?


texts: Watts P.M.P.O. and audio equipment power

texts:
I am a beginner in electrical engineering, and to begin learning I decided to look into audio amplifiers.
I have seen that the power of audio amplifiers is often described in the units of watts, watts RMS, and watts PMPO.
So far, the only one of those units that I think I understand is watts.
For instance, I just recently made my own audio amplifier circuit. If I think: "What is the power of my amplifier supposed to be?", then my thought process goes like this:

The transistors I used are the TIP120, which have a maximum rated
power of 65W. Then, I decide that 60W is a safer maximum which would be
reached if my amplifier runs 19V through one of my 6Ω speakers.
Therefore, the power of my amplifier is 2x60W.

Then, I look at the datasheets of audio amplifier ICs, like the TPA3116 that says: "50W into a 4Ω load at 21V", which makes me conclude that in that setting it'll output 14V maximum into the speaker, which I think makes sense.
But then, I look at the datasheet of the TDA7294, and they talk about "RMS Power" and "RMS Music Power", units which I couldn't find clear information about.
Then, I look at home audio systems, like a Panasonic Stereo System I have which has "9500 Watts P.M.P.O." written on the front.
9500W? That sounds stupidly high to me, but then I look again and it has 300W written on the back of it.
If I'm correct, maybe a 1kW home stereo system could make sense, but a 2kW or greater one would not exist.
So...
Are my conclusions about my audio amplifier circuit and the TPA3116 correct?
Are my conclusions about audio equipment power correct?
Are WattsPMPO, WattsRMS and RMSmusicpower, real useful units?


texts:
A Qsys system has to be generated to create all the source files for simulation and synthesis. Here it shall create copies of the primary RTL source files of custom components also.

These copies shall exist inside the simulation and synthesis folders inside the Qsys system directory, I never figured out why it has to create local copies.

If I am running a simulation, I would tend to modify the RTL file continuously, recompile it and rerun the simulation. This is just how development and debugging is done in general.

However, how will it work with Qsys? Do I really have to regenerate the Qsys system every time, so the source file in the simulation folder is updated before I restart and rerun the simulation?

Do I misunderstand how Qsys custom component verification is to be carried out?


texts:
How does assignment through a contribution statement (statements with <+ operator) works in verilog-a?

I read in the language reference manual of verilog-a the following about the branch contribution statement:

  The simulator adds the value of the right-hand side (of contribution statement) to any previously retained value for the branch for later assignment to the branch. If there are no previously retained values, the value of the right-hand side itself is retained.

Could anyone explain to me how this method assigns proper values for the branch current or voltage?


texts:
I needed to find time constant of the above circuit. I guess we should first draw small signal analysis.

The book found time constant as (RD+RL)*Cc. It says that we can find time constant using the effective resistance seen by the capacitor. I didn't get that point. Why did we add RL and RD resistances and then multiplied with Cc? How did the time constant become (RD+RL)*Cc?


texts: Is it possible to send arbitrary messages (as with printf()) via SWD for debugging?


texts:
Currently I am building my own AVR dev board, and I have been looking online about how to build the voltage regulator. I can build it, but I am curious as to why a capacitor is necessary. Also what devices how much capacitance you need?

Thanks in advance.


texts: Altium PCB, plated or unplated pads without hole, what is the difference

texts:
When I place a pad, there is an option Plated. Here is the picture

What is the difference between plated and unplated pad without hole?


texts: Determine the position of the charge for equilibrium

texts:
Question:

  A system of three electric charges lying in a straight line is in equilibrium.Two of the charges are positive with magnitude Q and 2Q,and are 50 cm apart.Determine the sign,magnitude and position of the third charge.

I am considering a negative charge in between the Q and 2Q lets say q and equating the force due to charge Q and 2Q on the charge q then i get distance of q from charge Q 20.7 and from charge 2Q 29.3 but that is not the answer given

answer is given like this
q shoulb be a negative charge with magnitude 0.08Q and located at x=54.15cm from Q and 4.14 cm from 2Q

whats mistake i am doing can anyone help me?


texts:
What are the advantages of stranded vs solid wire?

what should i be using for prototyping circuits?


texts: LTspice Transient Simulation with external components

texts:
My problem is that I want to simulate a circuit with a transient analysis but as soon as I hit the simulate button, the simulation runs and runs and runs and won't terminate (although my stop-time is already at 0.1 s). Since I don't have much experience in SPICE, I think my problem lies in the embedding of external 2 op amps. Therefore I followed these steps (correct me, if I did something wrong here):

I searched for the .cir files of the mentioned op amps and saved the files in the same directory, my schematic is located.
I looked for the name after .SUBCKT in the .cir files and auto-generated a fitting symbol. After placing it in the circuit, I renamed the value and set the prefix to X.
I used .include <filename>.cir to include the .cir file

After that I built my circuit and hit the simulation button. Anyone knows where my problem might be?

edit: Here are my circuits. I embedded the two op amps (there isn't any mistake in the pin connection)


texts: Reed Switches - Good brand, stuck in the closed position problem

texts:
I'm doing a project with an Arduino pro mini 3.3v that uses internal pull-up to detect changes on a reed switch sensor. I'm buying the reed sensors from AliExpress, and most of the time they work OK without problems, but in some random cases they suddenly stick together... if I tap on them, they open again and work properly... which is worse because it is hard to test if they will work for long term.
I cannot allow this to happen since what this sensor measures is the main purpose of the device, and I cannot sell a product knowing there is a good chance this can randomly happen, making the device unusable.
For now I'm using 2 reeds in series, and doing some failure detection in code. But I would like to ask if someone already had this problem, and ask for a good reed switch brand that is more reliable and maybe spare me this problem for good. I looked for good brands in the internet, but I haven't found enough information. I was thinking maybe also buying plastic ones since the glass ones break so easily.
FYI, the magnet is a small cylindrical 3mmx3mm neodymium magnet, which I guess is not too strong for a 14mm glass reed switch, at a distance of 2-5mm.
Thank you for your help!


texts: What are these SOT23 components in this RPM gauge circuit?

texts:
I'm trying to work out the input portion of the input circuit on a digital RPM gauge. It accepts a W input from a standard automotive alternator.

I can't identify the JCL446 which only uses two of its pins, the 2TC or the E4ED diodes. What are the SOT23 ICs likely to be?


texts:
I'm suffering from a bit of confusion here and I was hoping that some kind soul here would be able to help me out. I want to build a small DC motor circuit just for fun, but I can't understand some aspects of the circuit (shown in the picture below)

.

So basically I understand that Ic = Beta * Ib. Thus (assuming that D3 is 3.3 V and Beta is around 100), I can say that Ic = 100*(3.3/1000) = 0.33 Amps.

Then, in order to find the voltage available to the motor, I must find the voltage drop across the 33 Ohm resistor and subtract that from my power rail voltage (5 V).

So 5V - (0.33)(33)  =  5V - 10.89V

Which is quite clearly ludicrous. Can anybody quickly explain to me the fault in my reasoning? I'd really appreciate it.


texts: loading multiple shift registers from few pins

texts: We want to load two 32 bit data shift registers without concatenating them using 4 control lines (SI1, SI2 clock, latch). It can be done by bit banging but can it be done using SPIs using only 4 lines?


texts: Definition of Field Wiring Terminals as in UL 499

texts:
I'm wondering if anyone can tell me where I can find the definition for "field wiring terminals" as referenced in UL 499 "Standard for Safety Electric Heating Appliances" table 27.1 "Minimum Acceptable Spacings at Field-Wiring Terminals".

My guess is that they're talking about terminals that are intended to be connected/disconnected by the equipment user/operator in the field, but I see no definition that states that.


texts: What causes the small peak at the start of the spectrum in a spectrum analyzer?

texts:
There is a "DC" peak that is at the start of the spectrum. I'm studying the differences between superheterodyne and FFT spectrum analyzers and I'm wondering if the peak is caused by the same source or not.
Thanks


texts: How is the ATmega32U4 chip recognized via USB?

texts:
I have an ATmega32U4 chip which can be wired up on a PCB and connected to a PC via USB. When this is done, Windows 10 (if the proper drivers are installed) recognizes the device as ATmega32U4 chip.

What is responsible in the chip to respond to the USB connector? How does this work exactly?

Is that also a so-called boot loader which is stored in flash?
Is it software shipped by Atmel which is stored in flash? Because then what would happen when I rewrite the flash memory? Would it then no longer be recognizable by Windows?


texts:
I'm a beginner to microcontroller programming and the Proteus simulator.  I have a LED blinking microcontroller circuit diagram.  I'm trying to simulate it in Proteus.  The problem is there is no Vdd and GND terminals.

I know it's hidden.  After reading a solution I was able to set Gnd but I can't understand how to connect the Vdd terminal .

I want to know how to connect to Vdd like in the circuit diagram.

My circuit diagram:

This is my Proteus project so far and here is my project file if needed.


texts:
I have bought a new charger for my laptop. The case of my laptop is made of steel and so it sometimes give electric shock as I don't have a ground wire in my house.
And, I currently don't have any mood and time to call an electrician to get me a ground wire. Here is the picture of my laptop's charger plug:

Is there anything I can do to connect the ground pin like putting something in it may do the work or something else?


texts:
I am designing a heater block using 12 heaters. Each one has 200W/230V ratings.
I have decided to use 3 pole SSR for control heaters with help of PID temperature controller.
The SSR manufacture recommend connection method as below image. (Star or delta connection).

Manufacture recommended connection method

My connection method
But my heater voltage is 230V and I decided to use 4group of parallel connected heaters for each pole of the SSR. (Local phase to phase voltage is 400V and phase to neutral is 230V)
My question is "Is there any problem of my connection method relative to manufacture recommended(Actually not recommended. But its the mentioned method) method?"


texts:
I came across a question which says the following,i don't understand the question and how to come up with a solution

In fig,the data word to be stored is S=1001

a)If LOAD is LOW,what does Q equal after the positive clock edge?

a)If LOAD is HIGH,what does Q equal after the positive clock edge?

It'd be really helpful if someone explains the solution,I got the basic knowledge about flip-flops


texts:
I have a 10 kilohm potentiometer being powered by a twelve volt battery. After I run the circuit, the potentiometer begins to overheat. I thought that a 10 kilohm potentiometer could take 12 volts. Was I wrong or was it an issue with the potentiometer?

simulate this circuit – Schematic created using CircuitLab


texts: Does mAh measure how long a battery would last?

texts: I know mAh tells how much milliamperes a battery can deliver in an hour. But does that also tell how many hours the battery would last? Sorry but I don't really get it. If we're talking about a water tank, to my impression, mAh is like how big the faucet is and not how much water there is in the tank. I'm really confused as to why we measure battery capacity in mAh if my understanding about it is correct.


texts: MOSFET Vgs doesn't go to zero when controlling it with open drain output

texts:
I have this simple circuit to drive on and off a 12v rail from a microcontroller.

R707 = 10KOhm, R708 = 10KOhm, and Q701 is a P channel mosfet (IRLML6402TRPBF)

I'm driving this with a mircocontroller (3.3V). the EXT_READER_SHDN is configured as open drain output.

When EXT_READER_SHDN is 0 (connected to GND) I have :

Vgs = -10.72V (since the 12V is only 10.73V)--> the mosfet in this case is ON (conducting)and 12v_READER = 10.73V.

When EXT_READER_SHDN is 1 (pin floating) I have :

Vgs is around -2.66V (threshold is 1.2V)--> the mosfet in this case is also ON and 12v_READER = 10.73V.

I have already printed the PCB and need to make a temporary fix until the next version. Any ideas of a simple way to be able to open and close the circuit ?

I thought about reduicing the R707 value to likes 2 or 3 KOhms, but this will apply a hight voltage on the microcontroller pin. but since the pin is on open drain, doesnt this mean that I can go crazy and put 12V and have no issues ?

Thank you guys


texts:
I am using an NXP PCA9600 I2C bus buffer to drive a 2 meter cable in a two wire configuration. My clock is 100KHz. The bus voltage is 5V and the device sides are 3.3V.  I have 350 ohm pull-ups on the bus. There is also a Schottky diodes on both ends of the cable for transient protection when hot plugging.  The cable is an HDMI cable. One of TX-RX lines is twisted with logic GND as shown and the other TX-RX line is twisted with 5V. Each pair is individually shielded with earth ground. (not shown).

My scope probes are on 10X and have been trimmed.  In the scope capture, Blue is clock, Red is data and Green is ground reference. The attached scope trace is taken on the device side (SX & SY).  The trace shows the clock low to be ~0.6V above zero (green ground reference). Is this normal? Also it looks like the slave acknowledge (red) actually does pull the line to zero. The diodes are on the transmission side, so it shouldn't cause the 0.6V shift, should it?

The circuit work. The two I2C slave devices respond. However my questions are:

There seems to be excessive ringing as compared to some other I2C traces I've seen. What can be done to reduce this?
Do the bus side diodes need to be on both ends of the transmission bus or only on the slave side?
Do the device side pull-ups need to be both the same value? Would having different values cause the offset shown?

Any additional comments or tips are appreciated.


texts: Programmable Microcontrollers vs. SoC Devices

texts:
Context:
I essentially don't have a strong electrical engineering background. My knowledge consists in playing around with Arduino based microcontrollers or Raspberry Pis or equivalent SoCs.

Question:
What is the reason why a company would choose to design self made electronics with programmable microcontrollers instead of having a central SoC which runs an ordinary operating system, e.g. Linux, to handle all sensor inputs and processing. The target processing rate of sensor data (say 180 kB per time step) is 100-1000 Hz.

My idea behind this is the following:
A Raspberry Pi costs ~30$ and can handle all kinds of software, while a programmable microcontroller is essentially bound to compiled code in some self-written semi-compatible C/C++ language. Thus the development and maintenance cost for a SoC is way better. The processing frequency (max 1 kHz) makes me doubt that sophisticated hardware is needed here. Let's assume the processing steps are not too complicated. Assume that the CPU cost is not the main factor of the product cost. Size is neither a problem (A Raspberry Pi would easily fit). What are the bottlenecks of running a SoC in such a setup and thus prefer some self made boards with programmable microcontrollers (or even FPGAs)?

EDIT:
Assume the final product will be sold at 10k-100k$.


texts: Cannot program Xilinx FPGA with MicroBlaze project in SDK - missing download.bit file

texts:
I have a Xilinx FPGA project that I put together in Vivado 2014.4 (64-bit on Linux). The project uses a MicroBlaze. I've written my MicroBlaze firmware in Xilinx SDK 2015.1. My target hardware is the Digilent Nexys4DDR with a Xilinx Artix-7.

I've gone through the process of exporting my hardware design (including the bitstream) from Vivado. It was successfully imported in the SDK when I created my new firmware project. The Board Support Package also seems to have been created properly. All warnings and errors are resolved.

When I go to Xilinx Tools -> Program FPGA, I get this dialog:

I have verified that the files listed here do exist. RangeCompensator.bit and RangeCompensator.mmi are in the hardware platform specification project, and range_compensator.elf file is in the firmware project's "Binaries" folder.

When I click "Program", I get this error:

According to this post on the Xilinx forums, I shouldn't have to worry about the download.bit file if all the fields of the program FPGA dialog are populated, yet it download.bit doesn't seem to be getting generated.

How can I resolve the error during programming?


texts: Can I strobe a power led with an audio power amplifier?

texts:
I'm trying to make a fast LED strobe for visual periodic measurements of mechanisms, rotating objects to be specific. I "designed" an opto-coupler/MOSFET circuit and a transistor/MOSFET circuit. I plan to have an Arduino as the precision strobe signal source so i want to limit the current drawn from arduino digital pins to +-10 mA. After simulating both the circuits in LTSpice, i saw that i have to trade between base current vs. response times or peak load current. Maybe there is a proper way to design such circuits but I'm no expert. My goal is to strobe the LED with a minimum of 100 us pulses in 1000 us periods. I aim to drive a high power COB led that draw about 1 A in 36 V (40 W rated) so I could make an easily visible strobe.

Then came to my mind is that, why would I not be able to use an audio amplifier? The switching frequency i need is around 10 kHz (1 s/100 us), and audio amplifier input impedances are fairly high so Arduino digital output would have suffice.

Is it possible to strobe drive an LED with audio amplifier, with Arduino made pulse signal in the line input? If yes, how would I know the voltage gain of an audio amplifier which is rated by watts at certain ohm loads, so i could design a proper output voltage to drive COB LED?

Edit: schematics and LED current response added, the LED is modeled as a 40 ohm resistor (R2):


texts: Which isolated DC - DC converter solution is better

texts:
Based on suggestions by the previous question I cannot decide which DC-DC converter to use. The SN6501 paired with this transformer for 5v to 5v operation or the NXJ1.
My application is for this converter to power an ADC where the output of the converter will be feed to an ultra low noise LDO LP5907.
Here are my thoughts. The SN6501 for me already get points just for the fact that the datasheet shows applications of ADCs. Where the NXJ1 is appealing to me though is its smaller overall package, it seems to be not utilizing a transformer. Efficiency wise im not to concerned since i will only be using <= 100mA and the supply has ample of headroom (unless efficiency affects something else). Output ripple wise the NXJ1 has 20-50mV of ripple while the SN6501 does not say (since its only a driver). Isolation Wise both seems to be really good, since the circuit ultra worst cast 240V AC mains voltage (and its interfaced non-invasive so it not even connected). The NXJ1 can handle 4200V @1 minutes while the SN6501 coil's is 5000V @1 minute. about 20x safety factor.
I would like to hear what do you think, and which one would you choose performance wise, ingore cost. Im leaning to the NXJ1 just for its size, but if SN6501 performs even slightly better i will switch.


texts: What is the difference between these two op-amp circuits?

texts: I don't understand why when we design a proportional amplifier, the feedback has to be negative. When I run the simulation in simulink I get the same result for both circuits.


texts:
I got this SMT component that looks like resistor or capacitor.
The marking is 1407 15K
I enclosed the image, the size is about 4 mm X 5 mm


texts:
I am looking to use an SSR on an Arduino board (5v logic) to control a standard 120v light bulb.

I've heard people say you can "just drive this from a logic pin" - but the datasheets on the SSRs don't seem to (directly) indicate this.

The SSRs I am looking at (for example) describe the input voltage as "1.4 volts" - and show a condition, like "If=20mA".

So - does this mean I treat it like any LED - i.e. If I am driving it at 5 volts, I would (in this case) need to put a 180 ohm resistor in series with the input? From: (5v - 1.4v) / 20mA


texts: Digital replacement for Rotary Capasitor based fan speed controller

texts:
Is there a circuit using Triac and capacitor in series  to control the speed of ceiling fan? There is a circuit using SSR but I wish to use Triac as SSR are bit costly.

http://www.edcheung.com/automa/nohumkit.htm

Just for clarity the picture of the speed regulator is attached.

I have tried the circuit below. It works fine with one Triac wired but when both Triacs are wired and triggered one at a time, the Triacs fails randomly. Later it was traced that MT1 terminals of both Triacs are connected to LOAD which is a 60W incandescent bulb. So when a Triac conducts the MT1 and MT2 terminals of the other Triac also gets supply while no gate current is given. I think this cause the Triac to fail. Is this correct?

Is there a way to solve this.

Please help.


texts: New Rigol Scope is this Oscillation Normal?

texts:
I just bought a new MSO2000A series Rigol scope, 300MHz bandwidth version. When you set the timebase to 20ns or below, there is an oscillation present.
Can anyone else with this series of Rigol scopes observe this issue?
More info below

You can see it at all amplitude ranges, the oscillation always appears approximately the same size on-screen regardless of vertical scale.
This oscillation is in-phase even though it's not triggered on it, and it looks to be 500 MHz on the nose, so I strongly feel it's intrinsic to the scope, and either an artifact of the sampling itself or crosstalk from something in the clock domain of the digitizer.
Restarting the scope causes the amplitude to change randomly. Sometimes it is very obvious, sometimes not there at all. It is less obvious on Ch 2, which makes me further think some crosstalk/EMI problem as opposed to just a display artifact.
It is not affected by 50-ohm vs 1M input. BW limit has literally no effect (even on 20 MHz limit you can still see a 500 MHz oscillation!). Probe ratio selection makes no difference. "Invert" does invert the polarity of the oscillation. Setting coupling to AC has no effect, but coupling to GND causes the oscillation to disappear. Connecting a BNC short looks identical to a floating probe or no connection (as shown).
Turning on channel 2 (which decreases the sample rate from 2GS/s to 1GS/s) has a noticeable effect, slightly attenuating the oscillation. But still present.
I applied an external signal, and the oscillation was less obvious due to external noise, but still apparent, clearly a 500MHz periodic component on top of the signal.
Here it is again after a restart, looking like a good clean line. Nothing was changed other than turning it off and on.

Oscillation is still visible in dots mode. Here is the FFT showing a clear peak at 500 MHz.

Here's another observation, which I think might be caused by the same thing. When you zoom out the horizontal the baseline signal actually shows two strong bands, instead of one band strong in the center as you would see from a regular noise spectrum. This looks more like a sinusoid or bistable signal + noise. Shown below in both vector and dots mode.

The banding effect is also reduced when turning on Ch 2 (2GS/s down to 1GS/s shared sampling), similar to the oscillation amplitude being reduced.


texts: Dark detector with 555 timer and output pin has a LED

texts:
I am a complete novice and I had done it in a hurry with my kiddo around. I have redrawn it, with the values I used.

The circuit works. Also between pins 6 and 7, if I use a 100 K/10 K it works.

Just that I do not see a square wave.

I am just seeing multiple sites - and working with the available values for capacitors and resistors I have.

I read up the theory about the internals of the astable multivibrator too.

I need someone to explain it to me.

About why the circuit works, if the values of resistors are wrong?

Why does the LED stay lit continuously when I remove my finger, in some intensities of light and does not produce a square wave, I assume should keep blinking, if it stays on.

And what should be the right combination of the values of resistors?

I connected the pot using the circuit diagram below from 555 timer circuits.

But the way, I connected it was the base of the pot to the 100 K resistor in Pin 4 and the other two ends of the pot to Vcc and GND respectively. (In the picture base is connected to Vcc and one more end of the pot and the other end of the pot is connected to 100 K resistor with pin 4).

Have I connected the pot correctly?

I tried a simple astable multibibrator with the 555 timer.
Using LDR at pin 4.

I have tried to draw the schematic to the best of my ability.

Earlier in the morning when I had tried the circuit, the sun was on the east(my room is in the west), hence it was comparatively darker.

Case1:
When I used my finger to darken, the LED was turning on and was remaining on for ever, till I turn on the tube light for more light.
Case2:
The same circuit when I tried in the evening, with more light in the room, or vice versa (now am not sure), it works like a dark detector, the light does not remain on. When I remove my finger it turns off and when I cover the LDR it turns on.

In Case1:
My assumption is that when reset, the LED should light up and flicker (the square wave)

In Case2:
Seems fine.

I need help in understanding

why the light stays on and
secondly what is the calculation, governing the timing of charging and discharging (my case 10/k and 56K resistors), these were the ones I had and hence I used them.
Is case 2 correct, some more light on it, please.

I have attached a photo, when the LED stays lit. I have a video too, but am not sure it is allowed.


texts:
I have a design that has a +24VDC supply, a 7805 voltage regulator converting it to 5 volts and then a microcontroller and some peripherals behind the regulator.

The design and the 24V supply connector isn't meant for hot swapping, but users still do it. If the 24V connects before the ground, it seems that the 7805 acts pretty much as a short and everything behind it is at 24V (minus some voltage drop). When the ground connects a moment later, the microcontroller gives up the ghost, since all bypass capacitors have now 24V over them.

What could be done to fix this? Unfortunately the connector cannot be changed. I could change the regulator, but no datasheet mentions anything related to this. 7805 has a Darlington pair as an output transistor, would a MOSFET based regulator, such as LP2950 fix this? Another solution that came to my mind is using a 5.6V Zener between the 5V and the ground.

Edit

Here are the simplified schematics:

simulate this circuit – Schematic created using CircuitLab

Simplified because there are a couple more ICs, but those are connected as the microcontroller, with a 100nF bypass capacitor. Those ICs typically die as well.

Microcontroller inputs have no external pull-down resistors to ground, but I2C and reset are pulled up to 5V.

Only connector on the board is the supply connector, so ground loops aren't possible.

I found this forum thread discussing about the same phenomenon, and to quote: "Just tested it. 12.00 in 11.52 out. --- So, I guess that loosing the ground will fry your circuit."


texts: Simulating the capacitance of two (perfectly conducting) metal rods

texts:
I have two (perfectly conducting) metal rods (with a diameter of 10mm and a length of 150mm) which i put up (with a distance of 100mm from each other). Now I want to measure the capacitance of the two rods to each other with a circuit. For the environment of the metal rods I assume that it consists only of air. But later I want to bring other, dielectric, materials near the rods and measure the change of the capacitance.
For this purpose, I would like to simulate the experimental setup and look at the magnitude of the capacitance in different environments. It would be nice, but not necessary, if I could also simulate the impedance at different frequencies (~100KHz). Of course I know that my simulation, with this test setup, does not take into account the parasitic influences of the cables and circuitry, but I would like to ignore them for now.
My questions would be now:

With which simulation software I can simulate this best? This should be as well documented as possible and perhaps also freely available.
Can anyone estimate the magnitude of the capacitance and what kind of circuit I can measure it with?
How relate self capacitance and mutual capacitance to each other? What capacitance do I ultimately measure in this experimental setup?


texts: NE555 Controlled Transformer Voltage Spikes

texts: I am attempting to build a NE555 timer controlled step up transformer (3:250). R2 and R3 will be variable resistors when it is completed. Input is 12V and I'm stepping that up to about 1000V. The problem is I am getting these vicous voltage spikes caused by the rapidly collapsing magnetic field across L1 and consequently voltages way above 1000V on L2. Is there a way to control this as I only want about 1000V across R5?


texts: Built in Self Test - In Embedded memories

texts:
I am reading this thing called -BIST (Built in Self Test).

I understand that, before a module enters its intended functionality, this BIST is made to run within the module. Once, this BIST is passed, then, the module is allowed to RUN. Am I correct?

I just want to understand, how this BIST is implemented in Software? Like specifically, what happens during this BIST test with respect to Embedded memories in an Module?


texts: Triac Dimmer Supplying a Purely Inductive load

texts:
I was asked a question in my lab viva today, on a triac switch supplying a fixed value inductor of 0.2 henry.
How will the current and voltage of the inductor vary, if the triac's firing angle was varied between 90 to 120 degrees?
Explain the nature of inductors voltage under different firing angles.

My answer was that the voltage will follow the relationship of

$$V_{load}=V_{peak} \cdot \sqrt{\frac{2\pi-2\phi+\sin 2\phi}{4\pi}}$$

which I derived there only and the inductor current will be out of the phase lagging by 90 degrees to voltage.

Vpeak is the peak voltage of the ac mains supply and \$\phi\$ is the firing angle of the triac.

Apparently, this wasn't the correct answer maybe.

So, what might be the correct answer to this or perhaps the correct generalized way to answer this question?


texts: Why is connecting two different voltage sources in parallel dangerous?

texts:
I'm working through a circuit analysis text on my own for the purposes of getting started with Arduino. I just came across a box that explained why putting two different voltage sources in parallel is a bad idea but the explanation didn't quite make sense and now it's bugging me.

I'm aware there is another, similar question here: "What happens if I connect two different DC voltage sources in parallel?" but the answers aren't quite what I'm looking for.

What I want to know is: how do I calculate the voltages, currents and resistances in a circuit that clearly defies idealizations? For instance, how much current will my poor different-voltage batteries encounter, respectively?


texts: Dimmig universal motor speed control IGBT or Triac?

texts:
I want to control speed of 220VAC universal motor (Grinder) using Microcontroller, which method is better in comparison??

Using Triac which zero-crossing detection and control pulse generation for each cycle
Using retifier and capacitor to make High voltage DC and use PWM to drive IGBT
For me IGBT seem more easy to control because I can use high frequency PWM withour caring of AC zero-crossing. And my control loop can run faster provide more stable close-loop system.


texts: Is there any way to determine the correct voltage for a stepper motor?

texts:
I recently bought a CNC mini-mill at an auction. It is fitted with steppers on the three axis. The X and Y are the same, and the Z is a bit smaller (physically). All the markings were removed from the motors and they are painted flat black. Yet another reason to hate proprietary hardware. The machine was originally designed to use a custom controller which is missing.

My question is, can I figure out what voltage the motors were intended to run at?
Does the coil resistance offer any clues?
I have a good quality multi-meter, and I have already reverse engineered the wiring. I don't want to fry the motors though.


texts: Brightness on reed switch LED decreases with voltage?

texts:
I've got a pneumatic cylinder reed switch sensor which has the internal layout as per the attached diagram:

If I put 9v directly to it (without the load in the circuit diagram) then I get a strong LED illumination, however, if I wire it into the vehicle I'm using it on then the illumination isn't as bright and is illuminated for a shorter duration in the stroke of the cylinder (the magnet the activates the reed switch sensor is around 20mm).

I've tested the voltage on the vehicle at the terminals the sensor is connected to and it's 12v, so I would expect the illumination of the LED to be stronger - why isn't it?


texts: Why does the carrier wave amplitude have to be largest in amplitude modulation

texts:
I don't understand the reason for the following statements in amplitude modulation

Here's equation 3-7 described in the text


texts:
From what I know, potentiometers vary an analog current with an input usually in the form of a knob. And transistors vary an analog current with an input in the form of a smaller current.

Is there any practical difference between the two other than one varies between the position of a knob and the other varies between a smaller current?


texts: How can I quickly heat something to a given temperature with nichrome wire, while keeping the wire itself under a given maximum temperature?

texts: I'm trying to heat a fluid to a certain temperature (under 100C) using nichrome wire, with a thermistor measuring the temperature of the fluid to allow controlling the nichrome wire using PWM and a PID controller. However, it is absolutely necessary that the nichrome wire itself remain below 150C or so. I could just test different PWM values and cap the PID output to a value that never reaches the maximum temperature, but then initial heating from room temperature will be slower. Is there any other way I can achieve this?


texts: Continuous charging below nominal voltage

texts:
I have a rechargeable battery pack 4*AA of 1.2V NiMh type, which when measured fully charged (individually by a smart amp regulated charger) and without load shows some 6V. The load will be a PIC microcontroller drawing almost nothing almost all day long except for some 5-10 minutes few times a day activating a 5V relay.
To not change batteries too often I am considering to connect a 5V switching power supply from an old phone charger. It shows 5V both without and with load. Charger would only supply power and charge batteries when the relay is activated, thus hopefully prolonging battery life and not drawing unnecessary load when nothing needs it.

First worry is to not fry the chip, which can tolerate up to 5.8V, but the batteries giving out 6V.

Is that safe enough to just go with it and instead not have the batteries charged so high - charge them with say the stable 5V from the phone charger?
Will the batteries tolerate such below nominal charging setup continuously or get damaged or charged over the 5V up to the 6V?
Do I need to lower the voltage down to 5V from batteries to chip with some diode?


texts: Will multiple chips outputing onto a bus for a few nanoseconds cause damage?

texts:
I'm working on a home-brew CPU design, with the usual mix of parallel EEPROMs, static RAMs and registers, tri-stated onto a single 8 bit bus.

My /output-enable logic for three tristate-able chips on the databus is:

/Ken = /a
/Ren = /a nor /b
/Men = /a nor (/b nor /b)

Do I need to worry about the few nano-seconds during which more than one chip's /oe pin will be low, due to the differing number of gates?

Will current flowing out of a high output of one chip, into a low output of another chip, for less than 10ns cause damage?

If it would cause damage, how was this situation avoided in the 1970's-80's?

Update: Chips are:

http://www.farnell.com/datasheets/32783.pdf
http://www.farnell.com/datasheets/1911297.pdf
http://www.farnell.com/datasheets/2047758.pdf


texts: How to get rid of floating voltage on Bridge rectifier

texts:
I'm trying to implement a rectifier and AC voltage sensor. The rectifier part works just fine. I'm able to power my device without any issues.

Please look at C2 in the screenshot (Circuit schematic). This connector is connected to AC voltages.
Vin is rectifier and the DC part is to power the device.
AC-1 to AC-5 are AC voltages that are sensed at ADC-0 to ADC-4 respectively.
AC-6 is the neutral line of all the AC voltages connected to the board.

When AC (1-5) are connected to AC voltage, the device works just fine. No issues at all. But when AC-1 and AC-2 are connected to 120 VaAC while AC (3,4 and 5) are not connected to anything, ADC-0 and ADC-1 read the right value but ADC (2,3 & 4) read 7.5V while they should read 0 V.

I connected all the -ve terminals of the bridge rectifiers to have a common ground but when there is no AC voltage, the respective +ve terminals of the bridge rectifiers reads 58V (+ve is floating while -ve is grounded). Is there any way to fix this? cause my ADC is reading the incorrect value of 7.5V when it should read 0 V.

Thank you


texts: Check if signal drifts are temperature related

texts:
Let’s say I have an output signal vs time plot data of some opto-electrical device (a black box for me). If the device is exposed to sunlight the signal starts to drift to higher values.

Is there a way, using data anaylsis, to "proove" that the drifts are solely heating/temperature problem, like curve fitting analysis ?


texts: Can't get output after selecting sel=5'b101 from mux

texts:
module ram_mux(yout,data_in,enable,sel,clk);
input [3:0] data_in;
output [3:0] yout;
input enable,clk;
reg enable0,enable1,enable2,enable3,enable4,enable5,enable6,enable7;
input [2:0] sel;
wire [3:0] register [7:0];
reg [3:0] mux_input [7:0];
wire [3:0] temp0,temp1,temp2,temp3,temp4,temp5,temp6,temp7;
data_register  a6 (register[5],data_in,enable,clk);
buffer         a14 (temp5,register[5],enable5);
mux            a17 (yout,temp0,temp1,temp2,temp3,temp4,temp5,temp6,temp7,sel);
always@(clk)
begin

$monitor($time,"register[5]=%b,temp5=%b,enable=%b,enable5=%b,yout=%b,sel=%b",register[5],temp5,enable,enable5,sel);
#30 enable5=1;
endmodule
module data_register(yout,data_in,enable,clk);
input clk,enable;
input [3:0] data_in;
output [3:0] yout;
reg [3:0] yout;
always @(clk)
begin
    if(enable==1)
    begin
    yout=data_in;
//  $monitor($time,"yout=%b,data_in=%b,enable=%b",yout,data_in,enable);
    end

    else
    yout=4'b0000;
end
endmodule
module buffer(y_output,x_input,enable);
input [3:0] x_input;
output [3:0] y_output;
reg [3:0] y_output;
input enable;
initial
begin
assign y_output = enable? x_input : 4'b0000;
//$monitor($time,"y_output=%b,x_input=%b,enable=%b",y_output,x_input,enable);
end
endmodule
module mux(yout,temp0,temp1,temp2,temp3,temp4,temp5,temp6,temp7,sel);
input [3:0] temp0,temp1,temp2,temp3,temp4,temp5,temp6,temp7;
input [2:0] sel;
output [3:0] yout;
reg [3:0] yout;
initial
begin
case (sel)
     3'b000:yout=temp0;
      3'b001:yout=temp1;
      3'b010:yout=temp2;
      3'b011:yout=temp3;
      3'b100:yout=temp4;
      3'b101:yout=temp5;
      3'b110:yout=temp6;
      3'b111:yout=temp7;
      default:yout=4'b0000;
endcase
//$monitor($time,"yout=%b,sel=%b,temp5=%b,temp4=%b",yout,sel,temp5,temp4);
end
endmodule

As enable=1, register[5]==data_in will be executed. As enable5==1, temp5==register[5] ////temp5 loaded with temp5.

But when I select sel=4'b101 in the multiplexer in the testbench I can't get yout.

How can I solve this?


texts: Digital clock by atmega8 with timer1 and LCD display

texts:
I have written code to make a digital clock using timer1 and tested with Proteus (an Arduino simulator). That program has been downloaded into an Atmega8 and interfaced to an LCD display. Seconds are being counted perfectly in 1 second duration. But when second, minutes and hours are incremented to greater than 60 I see problems. To limit those value, I have written these instruction:

if (second==60)
{
  second=0;
}

But when the seconds reach 59, the LCD shows the next second's value randomly.  For example: 59,09,19,29,39,49,59.....99,10,11,12,13,14.

My code:

unsigned int second=0;

unsigned int minute=0;

void init_timer1(void);

int main(void)
{
    init_timer1();
    sei();
    Init_LCD();

    while(1)
    {
        goto_position_X_Y(1,0);    //first line first position
        sprintf(lcd,"second=%d",second);
        Send_A_String(lcd);

        goto_position_X_Y(2,0);   // second line first position
        sprintf(lcd,"minute=%d",minute);
        Send_A_String(lcd);
    }
}

void init_timer1(void)
{
    TCCR1B |=(1<< CS12);      // prescaler set 256;new freq=31250;
    TCCR1B |=(1<< WGM12);
    TCNT1 =0;
    OCR1A= 3107; // 16 bit max count value 65535,
    TIMSK |=(1<< OCIE1A) ;
}

ISR(TIMER1_COMPA_vect)
{
    second++;

    if(second==60)
    {
        second=0;
    }

    minute=minute+(second/60);

    if(minute==60)
    {
        minute=0;
    }
}

can you suggest me  that can  problem be occurred in lcd's program? Code:

Send_A_String(lcd); function of this instruction.

void  Send_A_String(unsigned char*String_data)
{
  while (*String _data>0) {
    send_A_data(*String_data++) ;
  }
}


texts: Discrete simulation of 3-phase inductive load

texts:
I would like to make a discrete time simulation of a 3 phase inductive load but I am struggling with the problem. I have this Y configuration in mind.

I'd like to simulate each current and Vn, given that V1,V2,V3 are not necessarly sinusoidal. Actually, I'm interrested the control of a 3-phase inverter and would like play with the timing of the gate driver pulses. I believe I need a discrete simulation if I want to apply non-linear inputs.

What I did

I started with a simple LR circuit.

I found

$$V_L = V_{in}-I[n]R$$
$$d_I= \frac{V_Ldt}{L}$$
$$I[n+1] = I[n]+dI$$

I tried that with a python script and a simulink discrete simulation and that behave well.

Now if I want to apply that thinking to my 3-phase load, I find these equations (let's jsut talk about branch #1)

$$V_{L_1} = V_1-I_1[n]R_1-V_n$$
$$d_{I_1}= \frac{V_{L_1}dt}{L_1}$$
$$I_1[n+1] = I_1[n]+dI_1$$

With this 3 phase load, I have a new variable: Vn and this is where I get stuck.

With sinusoidal, 120 degrees phase shift and perfectly balanced branch, I know Vn would be 0, but these are assumptions that I don't want to do.

I thought of superposition theorem. To do so, I would need to find an equivalent impedance for R2, R3, L2, L3, which I don't know how to achieve. Since I don't want to assume my inputs are sinusoidal, or even linear at all, I can't just say my inductors are reactive impedances and then simplify.

What are my options here?

I don't think Clarke transform would help here as my goal is to play with the PWM of each of the 3 branches. Do I need to resign myself into making a linear model of my signals? Such as decomposing square pulses into sums of sinusoids and then using superposition?

Thank you!

EDIT - Developped answer

Following UweD answer, I achieved t get a working discrete model of a Y connected 3-phase load. Here's what I got in the end.

Starting with UweD recommandation, we set:

$$ V_1-V_N=R_1I_1+\frac{dI_1}{dt}L_1 $$
$$ V_2-V_N=R_2I_2+\frac{dI_2}{dt}L_2 $$
$$ V_3-V_N=R_3I_3+\frac{dI_3}{dt}L_3 $$
$$ I_1+I_2+I_3 = 0 $$

We can then say:

$$ V_N = V_3+I_1R_3+I_2R_3+ \frac{dI_1}{dt}L_3+\frac{dI_2}{dt}L_3$$

Using first equation, we find dI2/dt

$$ V_1-(V_3+I_1R_3+I_2R_3+ \frac{dI_1}{dt}L_3+\frac{dI_2}{dt}L_3)=R_1I_1+\frac{dI_1}{dt}L_1 $$
$$\frac{dI_1}{dt} = \frac{1}{L_1+L_3}(V_1-V_3-I_1R_3-I_2R_3-R_1I_1-\frac{dI_2}{dt}L_3) $$

$$ \frac{dI_2}{dt}=\frac{1}{L_3}(V_1-V_3-I_1R_3-I_2R_3-I_1R_1-\frac{dI_1}{dt}(L_1+L_3))$$

Using second equation, we find dI2/dt

$$ V_2-V_3+I_1R_3+I_2R_3+ \frac{dI_1}{dt}L_3+\frac{dI_2}{dt}L_3=R_2I_2+\frac{dI_2}{dt}L_2 $$
$$\frac{dI_2}{dt} = \frac{1}{L_1+L_3}(V_2-V_3-I_1R_3-I_2R_3-R_2I_2-\frac{dI_1}{dt}L_3) $$

Then we equate the 2 expression of dI2/dt to find an expression for dI1/dt

$$ \frac{dI_1}{dt}=\frac{ \frac{-1}{L_2+L_3}(V_3-V_2+I_1R_3+I_2R_3+I_2R_2) + \frac{1}{L_3}(V_3-V_1+I_1R_3+I_2R_3+I_1R_1)}{\frac{L_3}{L_2+L_3}-\frac{L_1+L_3}{L_3}}$$

We now have an expression for dI1/dt, 2 expression for dI2_dt. The following discrete Simulink model works well and gives the same result as a SPICE simulator.


texts:
I am designing the following circuit to limit current inrush to a device on startup (to about 1.5 amps over about 3 seconds).  Rload is just for testing, the actual load is a bunch caps at 56v, but I have not tested with those yet.  Everything simulates fine.  I have bread-boarded the circuit and if I apply 12vdc everything matches the simulation.  If I apply 48vdc, it fails.  I see about 4 amps, which is the overload limit of my power source and stuff gets hot pretty quick. It doesn't appear to be damaging anything, because I can go back to 12vdc and it goes back to about 1.5 amps.  I assume it some kind of thermal runaway, but everything I have tried to fixed it has had little effect.  The base resistors do not seem to make a difference.  Before I added the emitter (ballast) resistors, I was blowing up transistors, so those seem to work.

So I expect this circuit to limit the current in the load to 1.5a when I apply 56v.  It doesn't, and I don't know why.  It works fine when I apply 12v.

Any ideas what is going wrong here?


texts: ESP12F (esp8266) every program is running okay but it's warm/hot

texts:
I have esp12F that programmed with USB-TTL from arduino IDE
The wires setup during program is running
USB->ESP12F
RX->TX
TX->RX
3V3->VCC
GND->GND
While on GPIOs of ESP12F
RST->VCC
CH_PD->VCC
GPIO 0->VCC
GPIO 15->GND
When i touch the ESP12F, i feel my thumb so warm and the feel like little near iron temperature. I dont have termometer. So i just tell what i feel, what im afraid is that hot state is indicating short circuit but i'm sure there's no short at there. If short, the blink program wouldn't blinked, the fact it's blinking. I'm not using any resistor for it, i'm just directing connect using cable jumper.
Or should i think that hot is a normal? Due to current that stuff needs?
Also im wonder are GPIOs on ESP12F is 5V tollerant? I have read many article, they are have different question that make me confused.


texts: Why does the speed of the Electromagnetic wave in the material depend on the frequency of the wave where as they are constant in vacuum (freespace)?

texts: I am confused on why would the propagation speed of any EM waves at ANY frequency is constant in the free space (vacuum) but they seem to disperse in any other materials as the propagation speed of EM waves in other materials depends on the frequency? Can someone give me a good proof of this phenomena with appropriate formulas?


texts: Testing motor using an identical motor in regen mode

texts:
I want to be able to test a motor (permanent magnet motor + gearbox) continuously in steady state mode at different operating points (torque, RPM,) to measure the efficiency of the motor.
Instead of a dynamometer where all the losses go to heat (this is in a low pressure environment with low heat transfer,) the idea is to load the motor with an identical version of itself.
Current idea for setup: DC power supply (w/ a DIY power analyzer for V, I measurement) -> test engine -> torque transducer -> load engine -> power generated goes somewhere.
I have been told that the test motor is capable of demanding a certain level of torque based on "regeneration mode."
I have no experience controlling motors, and have tried researching this problem, but have no idea where to start. Currently, all I know is that we want to hook up the regen power to the "same DC link."
Is this setup reasonable/possible? If so, and the regen mode control is non-trivial, how do I go about figuring out how to make it work?
Secondly, if we have DIY power analyzer on the output end somehow, is the torque transducer redundant?
Remember, we need either Pout/Pin knowing the operating point, or T × ω/Pin, for efficiency.
Where would the power analyzer be measuring exactly? I know on the front end there's voltage outputs on the power supply to measure current and voltage (and filter current).


texts: TONS of adhesive on Blown capacitors. Try to replace or swap in NEW BOARD?

texts:
I've read the HELP CENTER > ASKING page.  Not sure where I stepped out of bounds in the original post, but I've reduced the content to the following in an effort to comply:

At issue is the IP (Initial Power) board of a Samsung LCD computer monitor.  See picture.  The three large capacitors in a row have domed tops and the one at right shows a bit of tan/brown crud in the quadrant lines.

The resilient glop that covers the three compromised capacitors (GLYPTAL?) is removable (but not entirely) by slicing with an X-acto knife and yanking with tweezers.

The 3 large caps appear to be three of the same, but I can't remove enough white stuff to read and know for sure... The one I can read says "820uF25V" Any advice on whether they're identical would be much appreciated.  They measure approx 10mm D x 20mm H with lead spacing of approx 5mm (Olin's excellent suggestion was too tall at 25mm).

I have no way to TEST the board and I fear there may be other issues beyond the three apparently compromised capacitors.

In light of that, should I replace the board, or will replacing the three caps likely solve the problem?  FWIW, I did accidentally bend (and subsequently straighten) some of the longer leads of surrounding components while removing goop.  So I'm concerned that I may have loosened some other component(s) in the process...

Thanks, and MANY thanks to Olin for the outstanding, helpful post.
Tom

PS. If the post if off-topic for the TAG 'Solder' I tried multiple times to find a more suitable tag, but was told repeatedly that I don't have ample standing...


texts:
I am trying to build an amplifier using op amp 741. But I am failing to build it on breadboard.
I am connecting the positive end of a 9 V battery to pin 7 and negative end to pin 4. As per my knowledge and instructions available all over the internet. Pin 3 is to be connected with the input. The voltage source that I want to amplify has two leads coming out of it positive and negative. If I connect positive lead of my input to pin 3, where should I connect the negative lead??
Similarly, while measuring the amplified output from pin 6 what should be the other point of reference.
I am need of a circuit fix.
I am attaching the pic of the amplifier connections here. Your help will be really appreciated.


texts:
I will use a Beaglebone Black with a powered USB Hub to control a USB Microphone (PCM2912A) and a USB HDD.

The task consists in recording and writing the Audio directly into the HDD... Will I have bandwidth problem with a normal Hub? Can I record & write concurrently?


texts:
I am trying to repair an e-cigar. One of the ICs is cooked, it has 3 identical on board but I can not identify the company's logo to search for a replacement.

Been on the web for more than an hour already... I am out of ideas...
This is the logo

and this is the whole IC

Any help will be deeply appreciated :)


texts:
A real capacitor can be modeled using a series RLC equivalent circuit.
However, there are still discrepancies between the two.
I've generated a waveform from the lab and I've modelled the equivalent series RLC. Why are there discrepancies between the two circuits and how can I generate a model that more closely resembles the lab generated waveform?

The first image is the lab-generated waveform for the voltage across a 2.2uF capacitor, second image is the simulated waveform resulting from the series RLC equivalent. Both have 200k Hz, 10Vp-p square wave input


texts: Is it possible to transform a microwave transformer into a current measuring transformer?

texts: I have an old microwave transformer with only the primary coil and I'd like to know if I can modify it to transform it into a current measuring transformer.


texts:
I am working on a project where I am needing to power 13-20 LEDs of varying sizes and types from a single battery / battery pack.  I am generally a novice when it comes to circuitry, however, I have successfully made similar simple set ups before using resistors and a fixed 12v power supply and they still work after years of use.

My concern now relates to the voltage variability of batteries based on their charge and burning out the LEDs.  Should I use something like a linear voltage regulator (L7912 ?) in combination with the resistors to protect the LEDs?

Thank you.

Edit: Would a simple circuit with a voltage regulator like the below work?


texts: Multiple signals connected to relay through octocoupler

texts:
Is it possible to use multiple octocoupler transistors as switches connected parallel to the coil of the relay? I am worried about slight voltage differences across collector-emitter. Just like the image only multiple parallel octocouplers.
edit: I will just use transistor as somebody said in the well known OR configuration


texts: How would you go about creating a lux meter for very low light (0.0001 to 1 lux)?

texts:
I like to take pictures of the the sky in really dark places like Death Valley. To get an estimate of exposure times for the foreground I would like to measure the light intensity.

According to wikipedia https://en.wikipedia.org/wiki/Lux the light intensity can be between 0.0001 to 0.002 lux in these conditions. I can't find any commercially available light meters within that range. At least none that are affordable.

Does anybody know how to build a lux meter that can cover this range at an affordable price? It doesn't have to be calibrated. It's enough if I know that one place has half of the light another place has or similar.


texts:
After compiling my design using RTL compiler targeting 45nm library, the tool gives me an area report as below:

   Type    Instances    Area    Area %
---------------------------------------
sequential      2237  19102.387   15.8
inverter        6982   9830.896    8.1
buffer           535   1255.847    1.0
logic          33180  91031.529   75.1
---------------------------------------
total          42934 121220.659  100.0

What is the unit of the Area column and what is the meaning of this area number?


texts: Propagation delay in asynchronous counter

texts:
Are the ripple counters useful in real life?

I know, for example, if we set an up counter with 3 FFs, CBA. Followings are the block and the waveform diagram:

After the count 001, it will appear 000 (the 2nd CLK period), which makes the operation false. In fact, this situation is inevitable in real life because propagation delay is inherent for all flip flops.

As a result, I wonder how can we implement asynchronous counters?


texts: how to confirm that PCB Ethernet layout does not affect perfornace

texts:
short version:
- How to test if ethernet traces on PCB causing any distortions to the signal?
- Is it possible to generate ethernet signals from a windows computer and measure them with an oscilloscope on the other end of ethernet cable? Can I use a computer as an Ethernet signal generator?

long version:
I have a PCB board which are used to pass ethernet signal.
There are just 2 RJ45 connectors on these board and some other components which do not have relation to ethernet. On connector is used to plug computer another one is to plug a router to connect the whole system to the internet.
It was more a mechanical design decision to pass ethernet signal through the PCB instead of plugging a cable directly to the computer.
EMI tests showed that we have a few problems with an ethernet connection at some point. My goal is to verify with an oscilloscope that Ethernet traces on PCB do not add any distortions or PCB noise to the signal. And if they do, how bad is it. So, the idea was to connect a computer or generator to the PCB, PCB to the ethernet compliance fixture and measure ethernet signal generated by the computer or signal generator. Maybe to build an eye diagram.
I spend some time, but can not find a clear answer if a computer can generate ethernet signal without been connected to an active device like a router or another computer.
What is your opinion on this approach?


texts: Do certain types of electrodes work better than others in an area with hair?

texts:
In selecting components for an EEG development kit, I'm wondering if certain types of electrodes capture signals better in the presence of (a small amount of) head hair?

For instance options include:

Gold and silver cup electrodes*
Spider electrodes**
Webb electrodes***
Flat electrodes

and many others. My intuition is that the Spider or Webb designs might be better because hair could go through the gaps, but that's just a guess.

*Cup electrodes (shown with Ten20 conductive paste):

**Spider electrodes:

***Webb electrodes:


texts: Why do most h bridge modules have more leads than 2 inputs, 2 outputs, and 2 for power?

texts:
I have been looking for a simple h bridge for high power applications (say ~2kW total--whether that be 2kV at one amp or 2kA at 1V I really do not care. I figure I can always use a transformer to switch between the two). Anyway, the point is, I just want take a lot of DC power (two leads), and switch it across a load (two leads). In order to determine which way you want to switch it, you need two inputs (two leads).
Here are just a few examples of full bridge h bridges with redundant leads and/or leads that should be tied together but are not:

http://www.vishay.com/docs/94546/19mt050x.pdf

http://ixapps.ixys.com/DataSheet/MIXA81H1200EH.pdf

http://www.vishay.com/docs/93754/p100.pdf

Note the redundant leads on the first two. For example, in the second link, {13, 21}, {2, 19}, {10, 15}, and {4, 12, 14, 20} are clearly connected  by wires. What is the point of having multiple pins if they are directly connected by wires? Furthermore, the last link, the only way I know how to use that design is with {G1, G4} on and {G2, G3} off or vica versa. Why not just tie gates together so that is the case? Then you have two inputs (each connected to two gates) two outputs, and two leads for power.

Although I would not mind some examples of what I am looking for, I am just as interested in knowing how to take full advantage of these seemingly incomplete or redundantly wired h bridges.


texts: Calculating Slew Rate from a time-constant

texts:
I have to choose an op amp mainly based on slew rate. I am using the op amp as a differential comparator with dynamic (time) hysteresis with a time-constant \$3\tau=500\mu\text{s}\$.
My upper threshold of the hysteresis \$|U_{\text{th}}|= \pm 5\text{ V}\$ while my bottom is the minimal possible

How do I calculate the necessary slew rate given this?
Please keep in mind I am yet to add a voltage stabilizer in \$U_{\text{out}}\$ with a Zener.


texts: Difference between ARM A and M series processors?

texts: When I'm asking this, I think on microcontrollers, whats the difference between A and M series of ARM processors. Many microcontrollers such as Beagle Bone now have A type of Cortex?


texts: Bootstrapping a bidirectional MOSFET switch?

texts:
is it necessary to use a driver and bootstrap circuit in order to make this configuration work;

Or can I just stick 10V in it like shown?

This is to make a bidirectional switch, I'm not pulsing the MOSFET gates at a high frequency, simply turning it on or off depending on what I need, manually.


texts:
I have Kanthal A1 26AWG (3.21 Ohms). I need to heat a small cardboard box (Tissues box) 15 degrees Celsius over the room temperature. And I am using 2 D Cell Batteries of 1.5V.

I coil the Kanthal with a regular pencil, approximately as long as a finger. Then I connect a regular copper wire to one that goes to the battery and the other end to the opposite side of the battery. The problem is that it doesn't really heat. I need to make the coil as small as nail to make it heat to high levels. Any idea?


texts: How to improve hardware programming skills?

texts:
I am a newly graduated electrical engineer with little knowledge about microprocessors. I have studied with PIC, Arduino, STM and TI processors and even with fpga boards. The problem is my work remained superficial and I want to improve myself in this area. I would like to get advices from knowledgeable people.

I can read datasheet up to a point and using registers to program. Generally small led projects with microprocessors. More than that starts to confuse me and that makes me think I skipped important parts.

I found lessons on internet for STM32F407VG. It was going nice but I learned ST removed Standard Peripherals Library and switched to HAL. All examples gives error and I stuck in there.

Should I return to the one of basic PIC models and in-depth study all datasheet to understand structure? Or should I continue with ST discovery card? An engineer that I met suggested me to skip all these things and fresh start with fpga boards but that confused me even more.

Where should I focus? And can you suggest me a book or tutorial so I can follow step by step.


texts:
What: I'm designing a DC-DC Boost converter for a solar panel maxmimum-power-point-tracker (MPPT).

Setup: I'm using a TPS2819 MOSFET driver connected to a FQD16N25C N-MOSFET. The TPS2819 is driven by a 5V PWM source at ~500Hz. With the duty cycle set to roughly 50%.

Problem: The FQD16N25C gets very hot with a 48ohm resistive load on the output.

Shown below is the schematic of the boost converter stage:

A DC power supply was connected to input (Vsolar and GND). A 48ohm resistor was placed across the output (Vbatt and GND)

Shown here is the Vds wave form of the mosfet. With an input voltage of 2.64V, the current draw is 1.687A

From what I've read about N enhancement MOSFETs, what may be happening is that the MOSFET is operating in the linear triode region as opposed to full saturation. However, I'm not exactly sure how to solve this


texts: Amplifier circuit for Bently Nevada velomitor 330525

texts:
I'm in need of measuring vibrations and I have access to these Bently Nevada velomitors.
I'm not sure how to design a ampliefier circuit for the signal.
The datasheet is says that it is a piezo electric velomitor, but what is throwing me off is that it has power requirements of DC voltage -22 to -30 and bias current of 2,5 to 6 mA. The output bias is -12 +-3 VDC.
The output is 4mV / mm/s and I would like to amplify this by 100, so it would be 400 mV / mm/s. I cannot figure out how to build the circuit because it apparently needs negative volts and it is only a two wire velomitor.
Could someone point me in the right directions? I have dabbled with basic electronics but nothing really with negative volts and piezos.
Datasheet


texts:
I got a Microchip RN4871 BLE Module and want it to act as beacon.

So, I connected over UART and executed the following commands:

SS,20
SC,2
NB,09,656667

Whether I have configured the beacon properly. Which is the beacon format supported by Microchip. (iBeacon, EddyStone ). If iBeacon, how can I set the UUID, Major, Minor Number and TX Power..

Did anyone has success in using RN4871 Devices


texts:
I have a microcontroller-based project (using an Atmega328) that needs to detect the presence of a solid object placed on the project box. What would be the best way to achieve this? I've thought about using a photosensitive resistor in a voltage divider configuration, but the issue I have with this is that if the project box is in a dark room it may not detect any light when the object is removed.

Any and all input on this would be appreciated as I'm not sure how reliable my voltage divider solution is. The objects placed on the project box will be solid and made of glass or plastic. And the only output needed from whatever sensor I use is a logical zero or one to signify if an object is there or not there. Note the objects may have concave bottoms, so the sensor would need to be able to identify it even if it's up to 1-2 cm away from the sensor.


texts: Match Two PCBs Layout and Dimension in EAGLE CAD

texts:
I want to create a PCB (name A) where I can put another PCB (name B)  on top of it using Autodesk EAGLE. I need to match the PCB B's pads position while designing PCB A.

Here's the picture of PCB B :

In PCB A I have the same Con1 and Con2, and need to position them exactly as how Con1 and Con2 positioned in PCB B.

What I have tried select all / Group the PCB B and paste them in my PCB A.brd but got the following error :

I guess it's because I didn't put the schematic of PCB B on my PCB A's.sch
So I copy the PCB's schematic and paste them on my PCB A.sch, but when I get back to PCB A.brd, the PCB B appear unrouted, unlike the one that shown in first picture.

Please help me find the solution. My goals is only I could place Con1 and Con2 in my PCB A so that it's match the position of Con1 and Con2 on PCB B.

Thank you


texts: Using bit fields in interrupt-driven applications

texts:
When implementing interrupt-driven applications I usually create a bitfield to keep track of different interrupts. For example:

volatile struct {
    unsigned char ISR0: 1;
    unsigned char ISR1: 1;
    ...
    unsigned char ISR7: 1;
} ISRstatus;

The rest of the application might have the following structure:

ISR(ISR0) {
    // set status flag
    ISRstatus.ISR0 = 1;
}

void main() {
    while(1) {
        if (ISRstatus.ISR0){
            // serve interrupt
            /* ... */
            // clear status flag
            ISRstatus.ISR0 = 0;
        } /* ... */
    }
}

Recently I came across a few articles that suggested avoiding bitfields due to their unexpected behavior across different compilers and architectures.

Assuming my compiler is GCC, is it a bad idea to use this approach?


texts: Unknown components in a schematics of a Micro-USB connection

texts:
I'm trying to understand this schematics section related with a micro-usb connection:

I have three questions:

Why are the resistors with 0R? Is this a convention for a particular value?
Which electronic component is F1?
The same as 2 but for FB1.


texts:
This circuit looks relatively simple to build. I'm not going to bother with the transformer since I have a dc adapter. I was wondering how would I adapt this circuit to use a lm317 instead of a 7805. The maximum output is 1.5A. I presume I would need beefier transistors. However am unsure as the formulas at the bottom I never seen in my life. Could you point me in the right direction to understanding these formulas please? It's a 3.3v / 5v PSU selectable via SPDT switch.

Image from: http://apowersupply.com/short-circuit-protection-in-dc-low-voltage-systems-380.html

The reason I'm using this circuit is because it has an short circuit led. It's useful to have.

Am actually following spark fun schematic for a 5v breadboard supply. However I want a short circuit led as well as a power led.


texts: finding zeta and wn for a 4th order system?

texts:
If we have a 4th order system,such as the one in snapshot,

how we can find its undamped natural frequency and damping ratio?
Because  on wikipedia ,i found case of 2nd order system and couldn't find case/scenario of fourth order system

apparently another question on EE SE has same subject

How to find damping ratio of a 4th order system?

But the issue with this question is that it has no answer that is direct/simple and to the point as can be seen from the wording of those two answers ,they are containing a bit level of uncertainty, and the fact that OP hasn't accepted anyone of those two answers yet?


texts: Can daily 90VAC shocks have effect on human body?

texts:
There is external audio card on my desk with gold plated ports. For several years, whenever I accidently touch these with my elbow I would get a little shock, sometimes I would touch the PC case with my leg and get a tickle sensation. This occured on daily basis and I always put the blame on faulty electronics in the sound card. I did not pay too much attention to it.

Today I discovered that this was caused by the ground pin in the outlet being broken, so there was no contact and what I was feeling was leakage through my body to the ground.

I measured the voltage between the case and my body, and it is 90-150 VAC.

Being curious I want to know if there could be some long term effects in such situation. Could this do something to my heart or my brain?

I tried to look for peer reviewed articles, but I am not able to find the right keywords.


texts: Battery monitor with ADC (max 1.0V): can I use this resistor voltage divider?

texts:
I have a project with ESP8266. It will run with Li-Ion battery, solar panel to charge and a buck-boost 3.3V regulator.

I want to monitor the Li-Ion battery using ESP8266. It has an ADC with max voltage of 1.0V. So I'm thinking to use a voltage divider (see schematic). I set high value resistors to minimize power consumption.

Will that circuit work? Is there any sideeffect using so high values?

simulate this circuit – Schematic created using CircuitLab


texts: High density serial interface nonvolatile memory

texts:
I'm looking for a high density (>512Mbyte) FLASH or other memory device in a small package with a serial interface. I'm hopeful but I can only find sizes up to around 16 MB with serial interfaces.

Does anyone have any suggestions on where to look?


texts: wiring two SPDT relays to operate a 12v DC motor Forwards and Back

texts:
My knowledge of electronic components is limited, what training I have received comes from a 6-week course I took in the Army in 1984. So, yes I am in over my head but not on my own volition. I do have a young guy, Ken, with a degree of some sort related to electronics helping me.

The problem

I have a simple 12v DC motor and two SPDT Relays. I need to wire the relays so the motor will go up and down using momentary switches. There is no diode in any of the components.

I first followed the diagram pictured below that Ken sent me. I wired the rocker switch so that it received its power straight from the fused 12v line; I then placed a diode between the two motor leads. Nothing visible happens.

After that did not work, Ken had me switch some lines as you can see in the diagram below.

That kept blowing the diode.

Now Ken thinks I need two diodes and the diodes need to be connected across pins 85 & 86.

But, Ken also keeps trying to tell me the motor is bad.

The motor is fine. If I straight wire the motor it goes down, if I switch the connections and add the diode the motor goes up.

Please Help!


texts:
Is Input Offset Voltage perfectly proportional to output in an opamp? Such that if one where to enter 0V differential to the +V and -V inputs, the output would be A*Input_Offset_V.

Also, when using negative and positive power rails, the A*Input_Offset_V may appear as a negative or positive, right?


texts:
I have been trying for a few weeks to create a current limiter that fills my needs but I have failed.  Idon't even know if it's possible. Basically I want to make a current limiter that can work with many different applications. In this case linear power supplies. I want a current limiter that follows:
Adjustable 10mA - 3A
Easily customizable, i.e if i want to change the limiter from maybe 10mA to 1A or 1mA to 500mA etc.
I want the current to go through a NPN power transistor.
Is there a circuit available that can do all this? I have tried to simulate a few with a lot of googling but i have not found one yet.
I recently started reading about op-amps and tried to make a limiter using that. But I didn't really know where to begin.
Any tips on how to build this is appreciated!


texts: How to make 9V battery clip easier to work with breadboard

texts:
I just recently started to play around with electrics. I use a breadboard as a playground and I have to plug in and out my 9V battery so many times that the clip is now broken. The tip of the lead came off (see picture) and stuck inside the breadboard.

I found the lead of the clip is hard to work with in the first place. It's too easy to bend, and that makes it difficult to stick into the breadboard, don't you think? Do you have some kind of tricks to make it easier to plug in and out 9V battery, perhaps something with a stronger lead?