texts: How to pack oddly sized chunks of data into 128-bit FIFO

texts:
In my FPGA project we get a 100-bit wide vector on each 100 MHz clock cycle from a 10Gbps receiver. I can then compress it to 75-bit wide vector due to some particulars of the data.
I would like to pack this 75-bit data into some power-of-2 chunk so that it can be transferred on the USB FIFO (32-bit) or DDR memory FIFO (128-bit) with the best throughput.
My attempt:
Assume packing into 125 bits is "good enough". So the input is 3x25 wide, and the output is 5x25 wide. So on each cycle, 3 chunks are fed into a big shift register where new chunks come in on the right, and old chunks are being shifted left. Then the output selects 5 chunks at the appropriate offset. Sometimes it has to skip a cycle until enough chunks are present. The shift register is sized so that it can fit all the combinations of offsets that have to be selected.

So my question is basically, is this a common problem in FPGA designs? Does it have a name and a "proper" way to do it? Is there a generic way of solving this for all input and output sizes? Is there something obvious I'm missing where I don't have to waste 3 bits?


texts: Bus contention when addressing tristate buffers by decoder output

texts:
I'm currently redesigning the signal propagation algorithm of a circuit simulator I'm developing as a hobby project (https://www.antarescircuit.io).
In the new design, I'm trying to detect when conflicting signals are asserted to wires and issue a warning if this is the case. Now I get lots of warnings when simulating the famous MIC-1 machine according to "Structured Computer Organisation" by Andrew S. Tannenbaum. They originate from bus contention when reading register values from the CPU's scratchpad (aka register file).
The scratchpad circuit looks as follows:

The tristate buffers at the right side are supposed to control which register forwards its current value onto the CPU's B data path. The register is selected by 4-bit input "FB", whose value gets decoded by an 4-16 decoder.
The problem is that the decoder (like any combinational circuit) produces intermediate results due to propagation delays of the various logic gates it consists of. In the example above, register 6 is to be addressed, but for a short moment, the decoder sets more than one output line to "high".
The contention exists for 20 ns and is determined by one single gate delay. I've chosen this value for simulation because it seems to be in the range of typical real hardware gates. The signal then remains stable for at least 9'000 ns.
The root cause the contention is illustrated by the following snapshot of the decoder. The signals that run through the inverters take longer, and the output AND gates produce invalid intermediate results.
Note: The snapshot is taken from a test with a 3-8 decoder. The 4-16 decoder used in the scratchpad consists of two of them. And don't be confused by the "zero" bubbles at the AND's outputs. These are produced by the signal flow animation feature and represent the signals that are going to flow to the outputs with the next simulation cycle, thereby establishing the expected and correct output of the decoder.

The question is how conflicting signals at the outputs of tristate buffers can be avoided. I've considered the following options.

Fine-tune timing: Add non-inverting buffers with the same propagation delay like the inverters to the decoder to make sure that all signals arrive at the AND gates at the same time. This makes the simulation work correctly, but looks to me like cheating, and I'm not sure if this would really eliminate the problem on real hardware, where you would face varying propagation delays due to fabrication differences of the logic gates.
Synchronization: I understand that combinational logic generally produces intermediate results, and clocked circuits are generally used to deal with that. However, neither Tannenbaum in his book mentioned this problem when he explained the scratch pad, nor could I find information on the net that discusses whether it is legitimate to directly control tristate buffers with the output of combinational decoders. Trying to synchronize the output of the decoder would require significant change in the micro architecture of the CPU, probably involving the need to introduce another sub-clock signal.
Ignore the problem: I could easily ignore the problem, as the simulated CPU circuit works fine despite the temporary bus contention. However, I'd like to do that only if my design of the scratchpad is reasonable, and it is common to ignore such short and temporary contention situations, even when running the circuit on real hardware. But since these situation, at least in my understanding, represent temporary "short circuits" on real hardware, I doubt that these are acceptable.

I'm more a software engineer than an electrical engineer and am therefore perhaps just not aware of a possibly obvious solution to my problem, so any help is appreciated.


texts:
Brushed DC Electric Motor Use Brush to Energize Rotor's Pole at such an angle with respect to Stator Pole that it constantly runs, once applied dc power.

Can same be achieved for reluctance motor, Once I replace the magnetic stator of dc motor with suitable reluctance path stator ?


texts: Checking for short vs long press with debounce

texts:
I'm a complete beginner with Arduino but have done quite a bit of searching and can't seem to fix this problem.

I'm trying to create a procedure that is repeatedly called in the main loop() that will set a variable depending on the current state of a button, as well as the duration the button has been or was pushed for. This code is probably messier than it needs to be, but it just seems to leave the variable at 0. What am I missing?

There is code in the loop() itself that sets the rotaryButtonToAction variable back to noPress once it has been acted upon.

#define noPress 0
#define shortPressReleased 1
#define longPressReleased 2
#define shortPressHolding 3
#define longPressHolding 4

int rotaryButtonState;
int rotaryButtonReading;
int lastRotaryButtonReading = HIGH;
int timeOfLastRotaryButtonReadingChange = 0;
int debounceDelay = 50;
int longPressDelay = 300;
int rotaryButtonToAction = 0;

void checkRotaryButton() {
  if (rotaryButtonToAction == noPress) { // if there is nothing to action, check the state of the button
    rotaryButtonReading = digitalRead(ROTARY_BUTTON); // store pin's current state
    if (rotaryButtonReading != lastRotaryButtonReading) { // if pin state has changed from the last reading, set timeOfLastRotaryButtonReadingChange to the time of the change
      timeOfLastRotaryButtonReadingChange = millis();
    }
    if (millis() - timeOfLastRotaryButtonReadingChange > debounceDelay) { // if more time has passed than the debounce delay, change the action state of the button
      if (rotaryButtonReading = LOW) { // if the button is still pressed, set the action to indicate it has been pressed and is still pressed
        rotaryButtonToAction = shortPressHolding;
      }
    else { // if the button was pressed for longer than the debounce delay and was released, set the action
      rotaryButtonToAction = shortPressReleased;
      }
    }
  }

  if (millis() - timeOfLastRotaryButtonReadingChange > longPressDelay) { // if more time has passed than the long press delay, change the action state of the button
    if (rotaryButtonReading == LOW) { // if the button is still pressed, set the action to indicate it has been pressed and is still pressed
      rotaryButtonToAction = longPressHolding;
    }
    else { // if the button was pressed for longer than the long press delay and was released, set the action
      rotaryButtonToAction = longPressReleased;
    }
  }

} // end checkRotaryButton


texts:
I have been trying to design a trigger lockout circuit and I have been having some difficulties.
The circuit is taking as an input a 3.3v pulse.  These inputs can happen randomly and what I would like is a circuit that acts as a gatekeeper to determine which trigger signals get through.  The criteria that determines weather or not a given signal gets transmitted is if 3 seconds have passed since the last trigger that went through successfully.
Ignoring component values the circuit that I have been messing around with is in the image below.

This design doesn't quite work, and I was wondering if anyone here had any thoughts on how I might make such a circuit?  It is also a requirement that the output signal also be 3.3 volts or at least close to it.


texts:
I am making a simple robotic arm with atmega8 using two servos(two joints), I am using Software PWM of AVR and it is working damn perfectly for one servo. Then i attach another servo and both does random movements (sometimes don't move, sometimes out-of-bound), then while power on if i detach one then the other attached one starts to work correctly..
I think this is some voltage or current problem?
Btw i am powering my board with computer usb port 5v.
No need to ask for code because it is ok because one servo does well until other joins.
A little bit same question is asked by someone here but no one answered there so i wrote my own..

EDIT(1):
Upon getting answers that i have to connect external power supply for servos, i think making a small external circuit would work like this here, would this work?


texts: What are double-flat and single-flat soldering iron tips good for?

texts:
I'm picking out a new soldering iron and I like butane ones(but not closed minded). One very good looking iron I saw from Weller is the P2KC.

However, when looking at the available replacement tips for that iron, I don't see anything conical. There is single-flat and double-flat tips which are odd looking.

My uses for this soldering iron would be through-hole and SMD work. Is this iron not intended to be used on circuit boards, or are one of those tips just as good as conical?


texts: independent control of frequency and duty cycle in 555 timer (formulas)

texts:
I want to control frequency and duty cycle of output pulse of 555 timer. I
searched and find this schematic in a post in SOV but I don't know how
calculate frequency and duty cycle in the circuit.

simulate this circuit – Schematic created using CircuitLab

What formulas should I use for calculating frequency and duty cycle? I would appreciate if you could kindly help me.


texts:
I wanted to learn Interfacing a LCD with a LCD controller. Is there any guide or tutorial that I can learn from?

I wanted learn interfacing LCDs like these( http://www.aliexpress.com/store/product/Mp4-display-mp5-display-4-3-fpc-ftg430d06z-00-h334/718220_1193086318.html ) not the 16x2 character LCD or SPI LCD modules.

Thank You


texts:
i'm studying interoperability in the telecommunication field and i want to know we must do what to have an xbee module interoperable with other zigbee devices of other manufacturers (not Digi). I didn't understand what is the meaning of "zigbee feature set" and i am wondering if me as a user i have to pay zigbee alliance's loyalties in order to communicate with other devices

i am waiting for your responses
thank you !!


texts:
I wonder what series of 3.3V CMOS logic gates are the standard in the year 2015.

Decades ago, when I learned about digital logic the 7400 TTL series was just going out of favor for the CD4000 series.

I haven't used any bare CMOS logic gates and flip-flops since then except for toy stuff. Now I'm working on a design where I need some digital logic. The prototype is running using a CPLD, but that seems to be a bit overkill. The design is so small that I can fit it inside three or four logic chips.

Timing and current consumption aren't critical at all. Low price and high availability are more important.

So what kind of digital logic family is the industry using these days?


texts: what the best way to calculate Rg gate driver for Mosfet

texts:
I need to drive a MOSFET  IPW90R120C3 from Infineon
here the Specification of MOSFET

VDS @ TJ=25°C 900 V
Rdson @ TJ=25°C   : 0.12ohm
Qg = 270nC

Specification of driver IR2110

Isource: 2A
Isink : 2A
VOUT 10 - 20V
ton/off (typ.) 120 & 94 ns
Driver supply : 15V

The switch frequency    Fsw= 50KH

what the best way to calculate the resistance Rg  to drive proprely  the MOSFET ?
 best regards


texts: Bismuth or Indium solder - how do they compare?

texts:
In my previous question I focused on lead-based solder alloys (see Best solder wire - Sn63Pb37 vs Sn60Pb40 vs ...?).

Some of you brought new exciting solder alloys to my attention. The two most promising types contain either Bismuth or Indium.

Some questions:

How do they compare to each other on properties like:

wetting of pads and pins
interaction with fluxes
joint strength - brittleness (is this directly related to the "tensile strength (PSI)" column in the table below? Please enlighten me.)
price
...

How do they compare to standard solder alloys, like Sn60Pb40?
Any drawbacks?
Most of them are sold without flux core. Wouldn't that make the solder process very difficult?
What kind of flux should one use with Bismuth and/or Indium based solders?

Note:

Perhaps the following table might be of help:

This table comes from "Indium Corporation".


texts:
I have done a measurement with a vector analyzer in which I have connected a certain coaxial cable to the two port of the instrument.

Precisely, I have got a measure of the phase of S21 of this type:

You may see that the phase of S21 is a periodic signal with respect to frequency. Why?

I know that in a transmission line S21 = exp(-jβl), and so there is a linear dependence of it with respect to the frequency, not a periodic one,


texts: Power distribution problem in multi-camera usb array

texts:
Problem Summary
My MacBook Pro (development system) can successfully capture images from 24 cameras in the multi camera assembly we have assembled. But when our assembly is attached to a new Raspberry Pi 400 (target deployment system), Linux only mounts up to 18  of the 24 available cameras.
The RPi system log sometimes shows:
“USB Device over current status detected”
at boot up time if the assembly is already connected,  or at attachment time if the USB cable is connected after boot up.
I suspect that this problem may be a power related problem, but I don't know how to diagnose this problem, nor which steps I must take to repair the problem.
In trial and error Attempts to access more of the cameras on the Pi, I have tested configurations in which additional power input is provided to the hubs.  But these trials have not succeeded.
Details and Research
Our multi-camera array is made of 24 or 18 USB cameras and 4 to 5 USB 7-port hubs, that are attached to a controlling computer (Mac or RPi400) via a single USB cable.
The hubs can be optionally powered using USB-c cables.
I have attached this assembly to both my MacBook Pro (development system), and to a Raspberry Pi 400 (target deployment system). While all 24 cameras are accessible when connected to the Mac, The RPI will only detect up to 18 cameras, and sometimes it won't even find that many.
USB Camera array configurations:
Note that all cameras, hubs, cables and the USB port on the computers are all rated  USB3.

What I’ve tried:
I have tried connecting external power to zero up to all of the hubs.  I have tried them arranged in both spoke and daisy chain configurations shown for both 24 and 18 cameras.
I can put USB amp-voltmeters between any 2 USB devices, as well as on the power inputs to the hubs when they are receiving external power.
With external power to all hubs, the meter between the master hub and the computer reads a steady 5.15V and 0amps.
I am guessing that the difference between the Mac and the RPi response may have something to do with how much voltage or amperage the RPi USB port can handle, and that those values are different for the MacBook Pro.
I have uploaded a diagram of the 18 Camera Spoke Configuration with the measured voltage and amperage on each USB data line, and each power in line for each hub.
I used a USB voltage/amperage tester with a single camera, and it shows an initial voltage of 5.16V that drops to 5.12V immediately after connection, and then returns to a 5.16V steady state.
The LED string is reading 4.5V and 2mA steady.

What suggestions can you offer as to what Voltage and Amperage measurements should be measured, and where to measure them to determine what is causing the hardware errors.


texts: I read somewhere that the minimum voltage is 13.8 V, I would like to know if there is the chance to use 13 V, my SMPS can just offer that, and the cons using this voltage.


texts:
Is there a function to read the Vrefint_cal in Cubes HAL libraries? I'm using the F3xx.
I'd like to measure the supply voltage of the micro. The formula given in the reference manual is:

\$ \Large  VDDA = 3.3V \times \frac{Vrefint_{cal}}{Vrefint_{data}} \$

I've been searching through HAL (cube) and couldn't find a method to return the Vrefint_cal. The datasheet says that it is at 0x1FFF F7BA - 0x1FFF F7BB, but I find it silly that there wouldn't be a method to read it directly.


texts: 3bit Gray counter using D Flip Flops and logic gates

texts:
I am studying a lesson about Logic Design and circuits. I have a question I can not find the answer.
How can I design a 3-bit Gray counter using D flip flops?
I know what the Gray code is, I know what a counter, logic gates and D flip flops do, but I do not have an idea on how to do it.


texts:
I was reading a discussion on this below thread regarding shunt Vs. hall effect and had a few questions in mind. I do not have enough reputations to add comment on that thread hence starting this new thread.

Also being noob, my question may seem dumb to the senior fellows in the community. Here to learn.

The link : What are the advantages of a shunt resistor vs. a hall effect sensor?

1) Am I correct to understand the current probes such as Tektronix TCP312A are also "Hall effect sensor" type devices? IF true, next question is applicable.

2) According to the Pros listed by @Vladimir Cravero, it seems Hall effect sensor measures more precisely. However in this old post Agilent claimed they are inaccurate.

Link: http://www.electronicproducts.com/Test_and_Measurement/Benchtop_Rack_Mountable/Characterizing_dc_inrush_currents.aspx

Those two statements seems contradictory.

3) It was mentioned in the thread that HS won't work beyond 100Khz. But Tektronix TCP probe series has range of DC -100 Mhz. (Again only valid if answer to Q1 is yes)

Lastly, I cannot add appropriate tags such as "current-probe", TCP300, TCP312,  to this thread as I do not have enough reputation. Can admin pls apply it? Appreciate the help.


texts:
I have a device plugged into the wall with a 40W bulb on it.

  (40W bulb) ----Trans---- (wall ac source)
                   |
                   |
             (ardunio 5v dc)

my transitor is a IRFML8244TRPBF (little tiny thing)

I hooked up the transistor and to my surprise, the light turned on right away (it's supposed to wait until I supply current to the gate from the arduino).

Is it possible that this transistor is not the proper rating to stop the wall a/c?

if it isn't the proper transistor, could someone recommend one that is strong enough to block that will still allow me to control it with the arduino?

just to note, there are no short circuits, everything is hooked up properly.


texts: Electronically triggering contact pad buttons on a wired remote with a Raspberry Pi

texts:
I would like to control my AC with a Raspberry Pi. My system is similar to this one, although it is an older model from 2004.

Currently the system has a wired controller. There is no bluetooth, wifi, IR or RF. A wireless controller can be purchased for AUD$500 which would also require a receiver to be purchased separately.

I would like to interface a Raspberry Pi with the current wired controller instead.

I need to understand how to activate the contact pads electronically, but I have very limited knowledge in this area. I'm hoping that based on the images attached below, people are able to help me wire it up.

The controller has six buttons but 12 contact pads - two per button.

I will update this question to be more specific once/if I have details.


texts: Ideally I am looking for a single chip solution to PID control where ADC/DAC resolution is a minimum of 24 bits. Does anything like this exist or do I have to put it together from separates?


texts: With regard to the picture below, it says with an AC signal as an input, the output is a square wave. I am familiar with the uses of op-amps like in differentiator, integrator, inverting and non-inverting, active filters etc. But those I can memorize their configuration. But this I could not understand.


texts: How can we solve it for the value of current Ia?

texts:
By solving loop 4 using KVL,
 I4= -0.5Ia = -0.5(I4-I3)
 how?


texts: Why is the collector feedback bias popular in electret-mic preamp circuits?

texts:
I got some simple electret microphone modules and I've been experimenting with audio amplifiers. I googled to find some example circuits, and I found that most of them resemble the circuit above. I built this one and it works fine. If I'm not mistaken, this circuit is biased using the collector feedback bias.

Searching for a circuit, I noticed that most electret microphone amplifier circuits use the collector feedback configuration. I wonder why is it so popular, over other usually more common configurations such as voltage divider bias? I understand that the use of feedback in this configuration causes the amp to be more stable, but wouldn't a voltage divider bias have the same advantage?


texts: Hi I'm having trouble identifying this resistor with the color code. It's for a GK backline 600 300w bass head, the schematic calls for two 10 2w resistor ran in parallel. But I can't find it anywhere only  the 10 1/2 or 1/2w resistors.


texts: Confusion about when a JK flip flop is triggered

texts:
I started learning about latches and flip flops recently, and my understanding is that edge-triggered devices like flip flops ignore their inputs until the clock signal transitions from low to high or from high to low, depending.
This timing diagram show the output of a falling edge D FF that I expected in a particular edge case

Indeed, I found this very result with the following master-slave D FF simulated in software

Then I learned about the JK flip flop and, while I understand what it's supposed to do, I am confused about something.

With the circuit above I tried something similar to what I did with the D FF :

I expected Q not to change and stay low since J and K were not high when the clock transitioned from high to low.

This is why I am confused : to me, this contrasts with other edge-triggered flip flops like the D or T, which only change their output based on what the inputs were at the transition of the clock signal (whether rising, falling, or both).
Here, the outputs of the JK FF only change at the falling edge, but even if the values of the inputs are the same at two consecutive falling edges, if they have changed in between then the output will reflect it. As I had understood, this is not what an edge-triggered devise should do.
I believe it is due to the fact that this JK FF is realy two SR latches in series. So as long as the clock is high, the master latch can capture the inputs but does not need them to be held until the clock does back to low.
So the inputs are processed as long as the clock is high, but the output only changes on a falling edge.

I also read that other flip flops can be implemented using JK flip flops, which I'd understand if this circuit did not behave that way. With this circuit, if I connect J and K to a common input and invert the signal comming into K, as to implement a D FF, then the resulting circuit does not behave in the same way as the D FF I described earlier. Instead here is what the output does

Having a circuit only acknowledges inputs on a clock edge is a desirable property, but this JK FF that is shown everywhere seems to not work that way.
But again I only learned about them recently so maybe my confusion comes from the fact that I am missing something.
Is this behaviour normal or accepted for an edge-triggered flip flop?
And is there a way to change the circuit so that the inputs are only processed during a falling or rising edge of the clock?


texts: Wanting to make a LED flasher circuit with Mosfets

texts:
I have a 28 volts supply.
I have an LED with Blue lamp and White lamp .3 wire
I want to flash between blue and white at 1 hertz when the power comes on to the lamp.
I found a similar circuit in Forrest Mims book but he seems to use P channel mosfets .
I want to use N channel mosfets
Ive been A over T  meesing trying to design something but its a bit bigger than I am.
Can I get some help please ?
I attach a scan of what I have atm
[1]: https://i.stack.imgur.com/zdcs1.jpg


texts: Drawing a timing diagram for a circuit showing X, Y, and Z. What is Z doing?

texts:
I'm looking over the following question:

I have the answer, and for the most part, I think I understand the logic: y = z' and z = xy. There's a 15ns delay (10 from the AND gate and 5 from the inverter) when coming back around to z. But my question has to do with Z on the timing diagram:

First, how do we know when Z starts? It looks like it goes from 0 to 1 10 ns after x does, but why? Is that all there is to it? Also, what is determining when z goes from 0 to 1 (with the 15 ns delay, I guess)? I really hope my questions make sense and that someone can clarify what is going on in the diagram for me -- I'm sure I've overlooked something in the circuit.


texts:
I 'm trying to build a portable device running on battery.
It needs power at 2 different voltage: 3v and 4.5v
Is doing something like this a good idea ?

if so, what type of diode should be used here ?

Thank you


texts:
I read a few posts here about resistor in led applications. The thing is, the resistor was always use with a power source delivering a higher forward voltage than the led could tolerate(ex: a 9volt battery hook up to a 3w 3v led).But what about a power source that the voltage can be adjusted to fit the led? My science courses are long gone behind me so I want to make sure my project doesn't explode on my face ;).

Right now I'm building a led lamp for a photography project using a 400w 36V 11A Single Output Switching power supply AC to DC SMPS which has a voltage adjuster so I can go from 32.4 to 39.6V. I'm using 168 3w Leds for my lamp, with a voltage rating of 3.2 to 3.4V and 700mA of current. I hooked up 12 leds in series so I can put 36v to them and not pushing them too hard.  I have 14 series of 12 leds in parallels. The leds are soldered to a copper board that I cleaned with acid with the proper circuit to have 14 series of 12 leds in parallels.

My question is do I need to include resistors for safety let say a led in a series dies so it doesn't blow up the rest of the led in that series? Is it possible to put a resistor at the end of each series or I need to put a resistor after every led?

I took some measurements:

-The lamp is drawing approximately 4A at the power supply which I find odd since it should draw more power if the led are supposed to draw 700mA

-Power supply is pushing 36V precisely

-Measurements at the led give me 3v as it should

Maybe I'm wrong here but normally to calculate a resistor resistance you have to do R= V/I so 36V-(3V*12)= 0/.7A =0R

But the thing that is bugging me is the power supply is rated for 11A which is more of what the leds should take. Why my concern for a resistor somewhere in my lamp design.

Thanks for the help! I hope my explanations are clear enough!


texts: What should I do with Arduino starter kit?

texts: This is not actually a problem but I need your advice. I live in Greece and I want to start learning how to make things with Arduino. I can order the starter kit which costs 80 euros which is a good price, but with the shipping it's 100 euros (136 dollars). Should I save money to pay so much for this? I'm afraid that the starter kit does not provide enough for what I want to do and I will have to order more stuff. Just to have an idea how expensive they are (and not to mention the availability) 10 euros for few resistors are too much. What should I buy?


texts:
I'm currently working on developing myself a computer based on the Motorola 68000 CPU and am currently working on the RAM interface. Since I want a basic multitasking OS, I want to use 1 MB of RAM. SRAM of that size is hideously expensive (around $25) but SDRAM of the same size and speeds exceeding what I need are much cheaper.
The question is this: what would I need to do to make SDRAM work with a MC68000? I know that it needs a refresh clock, so would that clock need to be my system clock (20 MHz) or my bus clock (System Clock/4 = 5 MHz)? What else do I need to look out for if I want to use SDRAM?


texts: How to measure the voltage an appliance is actually drawing when connected to a solar panel?

texts:
Sine June last year I've been using a solar panel which claims to have a built in voltage regulator capping output at 18 volts DC, to charge Lithium-Polymer batteries that have an input range of 15V to 19V DC. Both use DC barrel plugs for input and output.

Recently I've been using a multimeter to test the panel's output in different locations and different times of day to optimise my setup, and today, I was surprised to see a reading of 21 volts DC.

I've read here in this answer to 'How to keep solar panel voltage at 24V?' that (if I understood it right) devices drawing from solar panels can usually draw only the voltage they need and not exceed it, meaning the voltage measured when not under load is (I believe) only the open circuit voltage i.e. max available and doesn't mean that this is the voltage a device will actually receive - but I'd like to be sure that this is what's happening in my setup, since sending too high a voltage to a li-po battery I rely on could be quite a big problem.

How can I measure the panel's actual output under load, when connected to my battery?

I've read a few seemingly related questions here, including How to measure the current in a solar powered circuit? and Current output of a solar panel when connected to battery and load, and while the question titles sound similar, the actual question content and specific circumstances are different enough that I can't see how to use their answers to solve my problem.

I'm currently in Sierra Leone which doesn't have many well stocked electronics shops, and even basic things like my digital multimeter or fuses of specific sizes and ampage have proved quite tricky to find here: if it's possible, I'd appreciate answers with basic requirements in terms of equipment (but if it's not there are ways to have things delivered from overseas, it's just very difficult).


texts:
Hi I'm a beginner on using an oscilloscope and I'm sorry if my question may be repeated in other posts.

I was working on a circuit with the following materials:

(1) an Al plate (5mm thick)

(2) a disk-shaped piezo transducer with special electrodes (product note)(product link)

(3) two wires

(4) a coaxial cable

(5) a Tektronix DPO4104 oscilloscope

So the PZT was glued on the plate, and wires were soldered on the PZT to connect to the oscilloscope.

I tested my setup by knocking the plate, and ended up with sudden voltage rise/drop for the knocks. But I noticed the continuous milli-volt noise signals throughout the whole process.

Are they actually noise or something else? How should I reduce them to less than 0.1V as maximum amplitude, or even none? Because I would latter want it to detect 0.3-0.4 V.

I've tried scaling, reducing record length, and switching acquisition modes to SAMPLE / PEAK DEFECT / HI RES / ENVELOPE / AVERAGE(with max value possible). But they didn't work.

Fig 1. Output Graph

Fig 2. Screen picture

Fig 3. Parameters of oscilloscope

EDIT:

Just to update, I tried putting a foam plastic plate under the Al plate and half of the "noise" amplitude reduced (though I want to reduce more)

The problem is not solved for the time being.


texts: arduino - how to read and control the speed of a 12V - four wire fan?

texts:
I want to read the rpm and control the speed of a 12V - four wire fan through Arduino. There are many articles describing the procedure, yet I have some questions.

Read Speed:

So, 12V and Gnd are connected to the who wires of the fan, and the third wire is connected to the Arduino's input pin through a pull-up resistor (internal or external), in order to read the pulses, thus the speed of the fan. I guess that it works like in the schematic below:

simulate this circuit – Schematic created using CircuitLab

If so, how much is the voltage that the input pin reads when the sensor switch is closed, 5V ορ 12V? I believe that it is 12V, but that would damage the board, right? Should I put something like an optocoupler between fan and input pin, in order to isolate them?

Control Speed

Just about the same question for controlling the speed. Can I stick the fourth wire of the fan to a PWM pin? Is it true that the PWM pole of the fan accepts max.5.0V? Just to be on the safe side, should I use a motor driver IC, like L293D?

Thank you


texts:
Reading a question on SuperUser where someone received an electric shock from a modem made me curious, how much power can a phone line provide?

(I'm not looking to do anything dodgy like try to power something, this is just out of curiously/amusement; in the UK phone lines operate at ~50v (up to 100 with an incoming call) enough to overcome the resistance of human skin in the right conditions. 10mA would give a nasty shock but 100-200mA has a high chance of fatality - in theory could someone actually be electrocuted by a phone line?)


texts: Drop-out voltage at the input using MOSFET

texts:
Please have a look at my below circuits.

The first one is an MOSFET. N-MOS.

Gate is fed with a function generator input of 5V peak to peak. 1kHz frequency. 1ms period. 90% duty cycle.
Drain is provided with 10V and the source is connected to a load resistor.

If I probe at the gate and the source, I get the below waveform :

Please consider only the yellow and blue trace in the above waveform. Yellow is probed at the gate. Blue is probed at the source of the MOSFET.

If I connect the MOSFET to the circuit shown above, i.e., my second circuit, the same FG input is provided to the GATE of the MOSFET.

Now, I probe at the point A and the Gate of the MOSFET. Below is the waveform :

Yellow is the GATE of the MOSFET. While blue is probed at Node A.

My questions are :

In the second waveform and the second circuit, shouldn't the voltage at node A, follow the voltage at the GATE of the MOSFET? The node A voltage should also go to 0V while the Gate voltage goes to 0V. Why am I not getting that 0V waveform at the Node A?
What effect does the resistor connected to the source of the MOSFET and the purpose of the C1 50nF capacitor in this circuit.


texts: Calculating resistor value and power rating for LED driving

texts:
I have seen many resistances with difference Wattage i.e 1/4W, 1/2 W, 1 W, 2 W ,3W etc.
If I have 3 W Load which is an (large 3W) LED in my case, which Resistance should I use?

Also The LED I am using needs 3.5V DC and 0.8 A current. I have a Battery which outputs 8V. How can I calculate the Value of the resistance which can drop 8V to 6V?


texts:
I'm trying to identify the following miniature female RF coaxial connector found on an antenna input of a cheap DVB-T receiver (Sencor brand). I would like to identify the type so that I can get a matching male connector. The inner diameter of the receptacle measures 3.3 mm and the depth is approximately 4 mm. The inner surface is smooth. There are no threads or indents visible. Since it is on a DVB-T receiver, I'm guessing the connector probably has 75 ohm impedance.

Other dimensions I could measure with calipers (approx. where I can only do an estimate):

The closest match I could find is the front end of a SMC plug (without the threads), however the barrel is just slightly too large to fit (3.7 mm diameter). MCX also appears too large (3.8 mm).
Thanks for any help.


texts: What are options for an optically-isolated power supply?

texts:
I'm considering options for an isolated power supply (1mA @3V) with very low noise pickup and capacitance to mains/ground. Is there a simple optically-isolated solution, preferably using an off-the-shelf IC?

I see no theoretical reason why properly coupled LED + photo-voltaic generator (ideally, integrated into an IC/package) would not do the job. I would be satisfied with 5-10% efficiency (but do not know to achieve that).


texts: What will happen if I use higher voltage capacitors in an inverter?

texts:
We have old textile machines (Riter ring machine) that have an inverter - very large size and it contains 12 capacitors (400 volt, 2200 uF.)

The problem is we have 20 machines and almost every month an inverter explodes and all the capacitors melt.

As a solution I am planning to use higher voltage (450 volt) capacitors.

Is that solution?

The capacitor link is here or at this link
or are there any alternatives?


texts: Make Input and Output circuit really I/O

texts:
I currently have a self designed I/O board. I'm using the LPC1768FBD100 Microcontroller NXP 3V3 and created 20 inputs and 14 outputs. My design allows only inputs to be inputs and outputs to be outputs. Below you can see the input and output part.

So right now I have dedicated output pins and input pins
What I would like to know is, What do I have to do electrically if I want to make a pin to be both Input and Output. Can I just connect the end of the input circuit to the I/O port and the beginning of the Output to the same I/O and add something extra electrical components to make that work, or do I have to change the complete circuit? Is there someone with an example or information about this?

LPC1768FBD100 datasheet.


texts: Looking for all-encompassing website to download standards (UL, NEC, ISO, etc)

texts:
TLDR : Frustrated with the way standards are handled in my industry bc they are important, looking for one website that does it all.
I am a controls engineer and have been in this industry for about 7 years now. One of my struggles is finding a website that is a one stop shop for all standards for my industry that do not charge an arm and a leg for one edition. One of my frustrations is something like UL508a costs about $500, but will reference other UL standards within, which also happen to cost $500 each. I want something that is subscription based for individuals, because I have also found it not popular for companies to pay for subscriptions to allow employees to download things at will.
I briefly worked for a robotics company and an integrator, and have seen many many references to all sorts of safety standards for robots, hazardous locations like paint booths (class 1 div 1 etc), and your typical UL and NEC standards for panels that also have many references to even things like fuse classifications (e.g. UL248-8 class J having its very own document)
I am not interested in using google every time I need to look something up and clicking through a 100 websites only to find a random PDF someone uploaded 10 years ago.
Has anyone discovered a solution to this, or am I just whining?


texts:
This is a rookie question, but I'm quite confused about the ECL termination used on the ADCMP565 evaluation board

First, in the IC datasheet, they show how to terminate the ECL outputs to drive 50Ω recievers.

The schematic they show is similar to what is shown in this application note, which is a series termination that assumes unterminated, high-impedance receiver inputs.

In the evaluation board schematic, you can see the termination at pins 2 and 3 for example, which uses different values for the resistors and the termination voltage in addition to using caps.

My questions are:

Why does the datasheet mention 50Ω receivers while the application note says that this termination is useful for high impedance receivers?
What is the difference between the termination shown in the ADCMP565 datasheet vs that shown in that of the evaluation board?
What are the caps in the eval board termination useful for?

Thank you.


texts: Why do current-feedback amplifiers have a higher bandwidth?

texts:
The advice when dealing with amplifying high-frequency signals always seems to be "use a current-feedback amplifier, not an op amp". (see 1, comments on 2, 3 and comments on its question) But why is this? What about current-feedback amplifiers makes them inherently faster than conventional voltage-feedback amplifiers?

I've also seen it said that their gain is largely independent of frequency, as compared to op amps which have a gain-bandwidth product that is relatively constant, meaning their gain is limited at high frequencies. Is this related to the high bandwidth, or is it a separate advantage of the CFA?


texts:
I was trying to represent a square wave with its Fourier series in Matlab. But as I increased the number of terms in Fourier series expression, the Gibbs phenomenon vanished and the edges of the resultant square wave appeared to be curved a little. Why does this happen in Matlab when it is impossible in theory?

This is my code:

clc;
close all;

f = 50;      %setting frequency as 50 Hz
t = 0:0.0001:3/f;

fourier = zeros(1,length(t));

for n = 1:1:50
   temp = ((2/(n*pi))*(1-cos(n*pi)))*sin(2*pi*n*f*t); %phase shifted by 'pi/2'
   fourier = temp + fourier;
end

%subplot(3,1,2);
plot(t,fourier);
title('When the number of terms is 200');
grid on;


texts:
I see the term WOW in spec sheets and drawings. I understand the term means a variation in a measurement (VSWR, Insertion Loss, Phase) over 360 degrees of rotation. But I have never correlated how the term WOW is connected to the meaning.

What is the origins of this term? Is it an acronym?


texts: ESD/EMI Design for CE, Recommendation seems wrong from test lab

texts:
I have designed a product for a customer, that now needs to pass UL/FCC/CE Testing, It passed UL & FCC but failed CE for both 8kv ESD and EMI. The Chinese test lab my client went through sent me back a markup of what they "did" and suggest. The images of the physical board do not match the schematic recommendation, and the schematic seems odd to me.

I was expecting more of a "low pass" filter design to stop ESD and EMI from entering my device via a micro USB port, and an LED close to the package edge (ESD only).

Below is what I was going to do, and what they propose on the schematic. Can anyone give any insight as to they they have Ferrite beads past any capacitors, and have two, one for a 1mA LED and the other for a up to 370mA LiPo charger?

Circuit And Failure Info:

My highest clock is in the micro controller at 1MHz, and I drive a 100mA fan with a 16kHz PWM...
I failed EMI for signals in the 100's of MHz, that are not integer multiples of 1MHz. So I'm fairly sure it is from the 3rd party USB charger that is charging my product.


texts: I keep coming across the term "bubble pushing in logic gates."

texts: Can anyone please simply explain to me what it is?  A simple little lesson or answer would be appreciated.


texts: tricolor single package LEDs do not have same intensity for each color, why?

texts:
LEDs that have 3-in-1 RGB capability where each is driven independantly of the other usually contain three seperate LEDs in a single package. Each of them is made using different material to get different light color. I see that this has two implications:

The forward voltage for each color LED inside may be different.
On the LEDs I have seen on the RS website, they always seem to have different luminousity per color. I assume this means that with same forward current per color, each color will have different luminousity.

The result is that using the same circuit for each color one will get different light intensity for each color, this will make color mixing more complex. Why are the LEDs not made to have same light intensity per LED and (always) with same forward voltage per LED inside the package?


texts: Keep spare LED bulbs or increase dimming?

texts:
I have a luminary with 12 light points for standard E14 bulbs and a LED dimmer in the wall.

Using Calex bulbs, I only need 6 bulbs, which I run most of the time at 80% light output (measured with the smartphone light meter).

I also tried Toshiba dimmable LED bulbs and I noticed that they produce a different dimming curve. Also, when adding a single Toshiba to 6 Calex bulbs there is incompatibility and all of them flicker alternatively (all the Calex on, Toshiba off, and then the opposite).

As result of the high price of dimmable LED bulbs in general, of the different dimming curves, of the potential incompatibility with mismatched brands and of the not always reliable lifespan estimates (especially with LED "filament" bulbs), I need to ensure that I won't need to replace all of them as soon as one fails.

I see two options: buy some spare bulbs or install more bulbs and run them dimmed further:

if I install 3 more bulbs I will need to run them at 60% instead of 80% light output, thus reducing the heat load on each one significantly
if I keep them as spare, I know that I will have compatible bulbs ready.

I am not sure about the advantages and disadvantages beyond the two obvious ones I mentioned. How to choose?


texts: Is there a way to take a battery power source at 7.1volts 15Amps and convert it to 5volts 4Amps?

texts:
I'm somewhat new to electrical engineering, I've been messing around with Raspberry Pi and I'm trying to use a 18650 battery pack (2 batteries) to power a Raspberry Pi (and some other things such as a Fan HAT).
I'm trying to convert that 7.1volt 15Amp battery pack to something around 5volt 4Amp. How should I go about doing this? Would it be easier to try and find a battery pack for 5volts 4amps?


texts: How exactly should I build a smart wall light switch for a smart home

texts:
I'm planning to build a smart home system and as you know smart wall light switches are a important part of it. I've been digging around for almost two weeks but still couldn't find what I'm looking for.
I have designed a small zigbee module so I can implement it inside of wall switches and make a network of them so one can control entire network with something like a touch panel board or even his smart phone.

Mechanical wall switches:

I believe I can't use traditional mechanical light switches because they make contacts all the time and they produce big sparks and they would mess everything while I want a reliable wireless link. Besides I need a relay or something else to bypass the switch when it's going to be controlled wirelessly. Plus one has to consider a small AC/DC to provide DC voltage the wireless module need. I think It doesn't seem like a very good idea after all.

Touch wall switches:

I searched for touch wall light switches which are not very expensive but apparently they are packed and there is no room for you to implement your wireless modules inside of them. It was nice if I could do that because they have built-in power transistors and you can control the switch functionality with your wireless module. Plus these kind of switches have AC/DC converter circuits inside and one can use it's output for their specific purposes like powering wireless modules.
But apparently they have their own problems. First of all they are packed and even if they weren't there isn't enough space. Second is the matter of stability and life time. Apparently they start showing functional problems after a couple of month and you have to replace them after a while unless you use very high quality products which isn't worth for my purpose.

Although there are some touch switches with built-in zigbee controller but they have their own remote controller and I guess you can not control them because you wouldn't know what command to send.

So I think I facing a dead end here. I'm asking you What would you do?
Is there any way around this problem?


texts: My voltage multiplier (cockroft-walton) will not charge my capacitor bank past 150v. How can I fix this?

texts:
I got 5 free 450v 4700uf capacitors that I put in parallel to form a 23500uf 450v capacitor bank (2.4kJ) in hopes of building a can crusher and later a railgun. I built a voltage tripler from four 350v 10uf capacitors and 4 400v 6A diodes. It outputs 500v (which is okay because the capacitors have a surge of 550v),  but the capacitor bank still won't charge past 150v. I assume this is because the charger is not outputting enough current to compensate for the capacitors' leak rate. When I try to test how much current it is outputting with my multimeter, the first capacitor in the charger dies, so I don't have any way to measure the current (and my scope maxes out at 400v).

Is there a simple fix for this? Or am I better off using a different charger design? What other charger designs could I use? Thanks.


texts: Charging Multiple 3S Lithium Ion Packs Together

texts:
This is my current situation, just to provide background:
I wanted to build these small battery pack modules that were 3S2P as a modular system, where a pack could be used with many different purposes like powering a power bank or a light or powering my Segway or acting as a power all during a power outage. I’m planning to add a BMS/Balance board to it that is 25A. The cells I will be using are the Panasonic NCR18650Bs. Their charging current is 1.6A and I have 2 in parallel, so that would be around 3A just to be safe.
Now onto the part I’m having trouble with:
How do I charge these? I want to build a box on the wall that has slots for these packs to fit into. When I stick in a pack, I want to it automatically charge up at the right speed (so 3A I think). I also want to be able to add and remove packs anytime I want, without the other packs killing a pack. I also want this panel, regardless of how many packs there are in it, to be able to work together to power something if the power goes out. I understand that I might be asking too much of these batteries, so if making them work together to power something is not possible, then I would like this panel to just be a large charging station.
Another thing I want to add in the future is a solar panel with a solar charge controller that will be charging 24V batteries. These will also act as a backup when the power goes out and I also want this to charge the other packs, if that’s possible.
Also, since I want to be able to just stick these packs in without messing around with plugging in wires, would it be better to use XT60 connectors built in? Are there other connectors that will be better?
I know this is a lot and I might not have explained everything that well, so if you need any info or I’m not clear on something, just ask, I don’t really have a lot of experience building and working these battery packs.
Thank you for reading this and any help you can provide would be greatly appreciated!


texts: Edge-mounted vias... or how is this called? And can PCBs services manufacture it?

texts:
As you can see, the through-holes (vias) are at the border of the inner cutout. (rendering is wrong of course, as vias are not cut)

I imagine a manufacturer first prints the board and then cuts it, so that will be no problem to produce - correct?

And how does one call such border/edge-mounted, cut-in-half vias?


texts: Adding relay to turn off laser printer from lpt port

texts:
I intend to deploy an ancient, but perfectly fine HP Laserjet 2300L via parallel port to a jet direct (yes, ancient technology too)
As the printer is in the basement, and we only print rarely, I want to turn off the printer, when not in use.

Would it be possible to use the STROBE signal to trigger a (solid state) relay to turn on the printer for some minutes? Or would the SELECT IN pin from the jetdirect signal if the printer was needed for the forseable future, and turn off, when the queue is empty?

Or should I for a microcontroller to keep the STROBE from the printer until it's turned on, and to prevent power-on noise on BUSY to fool the jetdirect to think the signal is received?

I guess SEL, PE and BUSY should be simulated to allow the Jetdirect to send something in the first place.


texts:
How to close a circuit using a 5V power signal?

Essentially the goal is turn on an AV receiver, using the internal power ON/OFF switch, to activate using a 5V control signal.  The receiver now uses a mechanical switch to bridge a signal wire to ground to somehow activate the system power relay. So internal ON/OFF signal wire to gnd starts system.  I tested a 220 ohm resistor across switch, which did not work. Only shorting switch pins turns on the system, where one pin is gnd.

When I tested a 2N3904 transistor, 5V & 20k ohm on B, CE resistance still was ~300 ohm measured on a multimeter.  Which is not grounded.

If you can help I will truly be eternally grateful. Thanks, Mike


texts: Datasheet/pinout for S116T (1A 400V SCR)

texts:
In my inventory, I found a component labeled S116T.
I bought it a long time ago from a shop which describes it as "THYR 1A 400V".
So the device is an SCR, but I can't find any datasheet for this part online.
If no one can provide the datasheet, then can someone at least provide the pinout ?
Note that the component comes in one of TO-18/39/46/52 (metal can package).
Thank you in advance.


texts: Failure of a C cell in a 4x battery pack, potential causes?

texts:
I am trying to understand failure of cells in battery packs of 4 x alkaline C cells (in series, so ~6V output). The failed cells, from 2 separate battery packs, have bulged and leaked out, you can see the photo below:

Unfortunately I didn't get a chance to see the battery pack as whole unit before I started investigating but I've been told that at least 1 cell (not clear if it is the affected one) might have been placed in reverse polarity in the battery pack.
Would I be right in thinking that given that a cell might have been placed in reverse polarity, it is possible perhaps that somehow other batteries around it (with more charge than the affected one, possibly) could have caused a "reverse flow" of sorts and heated up the cell to the point that it vented out its innards?
These battery packs were assembled on the factory floor so it is also likely that some of them were dropped on concrete floors before they went in the packs, seems unlikely but do you reckon the combination of the reverse polarity plus potential damage from a fall could have contributed to the failure?
Difficult to get to the bottom of this with unknowns but I guess the jist of it is: Can a reverse polarity cell, in a series arrangement, be damaged by other cells around it?


texts: Use regulator when input voltage is above threshold other wise use direct input voltage

texts:
I don't have much practical knowledge of electronics. I am trying to operate esp12e with single Li-ion battery with charging circuit. I am planning to use a good LDO regulator because Li-ion battery voltage can get high upto 4.2 volts while we need 3.2-3.6 Volt for esp.
My problem is when the battery voltage is dropped below the certain level (near 3.4 volts), the regulator will not be able to further drop the voltage and stop.At this point,I want to use the battery directly, without the regulator.
How can I achieve it? Please help.


texts: Why must Integrated Circuits be baked (in the oven) before being used on a prototype board?

texts:
Why do integrated circuits mostly QFN, need to be placed in the oven for an hour or so, prior to being used on a prototype board?
Is it to somehow improve the protection of the ICs against ESD or just a way of stimulating the silicon?

I saw the process being done in an IC design company.


texts: Possible battery solutions for 1000mAh capacity and >10 year life?

texts:
I'm looking into the possibility of running a wireless sensor node for up to 10 years on a single battery. I think the average current draw is likely to be around 70uA, with the peak current draw possibly being 20mA(the average takes this into account). System voltage can be between 2.5-3V.

This seems like it might be a requirement in more and more projects as the area of IoT and remote sensors continues to grow. I was hoping to get some suggestions for a few different possible solutions that balance cost and capability.

I thought about a CR123A as a possible battery, or even just a couple of AAA batteries. A li-ion rechargeable cell was also a consideration, but I think maybe the self-discharge might be a factor after that length of time and recharging/energy harvesting might be difficult or costly.


texts: How to connect a relay to 220 Volts outlet?

texts:
I used relays before but just for simple 5V DC signals control using a Raspberry Pi. Now I'm quite cautious and would like to ask for some help from professionals because I'm not planning to set my apartment on fire.

What do I currently know about this?

I currently use the relay to switch on/off my computers. Doing this is very simple. Since computers turn on by shorting two terminals, I just took a branch from the power buttons of my computers and hooked them to a relay (like the one in the picture) to the terminals are not connected by default. I have a little script that switches the relay for 0.5 seconds, which is enough to turn computer on.

The problem:

Now I would like to use this to control some 220 Volts power outlet. For that, I bought a socket, like the one in the picture, and mounted it on a plastic project box:

From that socket comes 3 terminals, two terminals (call them black and red) and earth in the middle (call it green).

I would like to install an IEC socket on the box, too (like the one in the following picture):

The question:

How should I connect the outlet socket to the IEC through the relay? Please advise.

If you require any additional information, please ask.


texts:
I need a small dc motor for a momentum wheel. To conserve power the motor will be turned off once the wheel has reached target RPMs and left off until the RPMs fall out of the target range. This will require a motor that coasts with minimal mechanical resistance when off. Brushless DC motors seem like a good fit, but the permanent magnets in most BLDC motors have a small attraction to the solid core in each of the windings. I've considered modifying a computer fan BLDC to have an excited rotor, but i would really prefer to get something off of the shelf.

Here's my setup:

Power will be supplied by four AA batteries(6V) and the momentum wheel will weigh at max 100 grams. The motor and wheel will be mounted vertically and i a am looking for RPMs between 4,000-10,000 (the higher the better). Spin up times aren't critical so i have some flexibility as far as torque is concerned.


texts: Why is the impedance zero at cutoff frequencies in a series RLC resonance circuit?

texts:
I see that, in many derivations in the frequency analysis of series RLC circuits, \$X_L - X_c = R\$ or \$Xc - X_L = R\$ is considered at lower and higher cutoff frequencies.
So does that mean that the impedance \$Z = \sqrt{(X_L-Xc)^2 + R^2}\$ is zero at cutoff frequencies?


texts: Does VHDL permit logic operation in port map

texts:
Does VHDL and here I am talking about the latest standard, permit one to carry out logic or arithmetic operation in port map e.g

U0: DUT port map (reset => (reset or clear), in1 => (a xor b), in2 => (p+1), out1=> q)

Note: in2 is unsigned or integer type port. Rest are standard logic ports.


texts: In this circuit the LED flashes on and off, however could it be classified as an astable multivibrator?


texts: Can I use an ethernet jack to send LVDS signals?

texts: I would like to use an Ethernet jack for the form factor and CAT5e+ cable properties (shielded/twisted, characteristic impedance, etc) to send LVDS signals over a long length of cable (100+ ft).  When choosing board Ethernet connectors, I see that there are all sorts of types out there.  I am going to use the RJ45 T-568B wiring scheme, but then there are choices between magnetics, and I assume, no magnetics.  Can I take advantage of the magnetically isolated jacks with an LVDS signal (coming from SN65LVDS31 driver), or will it likely interfere? My speeds will be in the 25 Mbps range.  If the magnetic jacks will interfere, are there standard pin to wire type RJ45 connectors (no magnetics)?


texts:
I am using 24LC256 EEPROM which have addresses from 0x0000-0x7fff. But I would like to predefine certain address from EEPROM to specific tasks, like from 0-100 for task-1 and so on.

Does predefining those addresses in the C code work?

Like:

const int add[31] =   {0,4,8,12,16,20,24,28,32,36,40};

Will it work or should we point address as 0x0000 - 0x7fff?

And my other question is, how much delay must be done after writing operation (simple write/Page write) in an EEPROM.


texts: What is the relationship between an amplifier's step input and the frequency sweep response?

texts:
What is the relationship between step input response and the frequency response of a system such as an amplifier?

I see similarities between the step input response of an amplifier and the frequency response of an amplifier(how gain changes with the frequency). Of course this could apply to a filter as well.

Does that mean I extract the same information about an amplifier's gain versus freq by 1-) applying a step input and recording its response 2-) sweeping the amplifier input between zero to max freq. and plot the frequency versus gain?

Im not into the subjects much but I would like to have an overview between these two concepts and similarities. Even though I sense some similarities there is still some fog in my mind related to some missing math or concepts. Would be great to link or relate them as a big picture.

Is that because the sharp step input includes many sines already embedded in it?


texts: The Effect of Input and Feedback Capacitors on an Operational Amplifier Open-Loop Gain Response

texts:
I have the following circuit that I want to compensate:

As shown from the step response, the circuit is unstable because of the high input capacitance (the green plot is without any additional input capacitance, while the blue plot is with the 520 pF input capacitance connected). I plotted the open-loop gain AC response to calculate the phase margin:

As can be seen from the plot above, the phase margin is around 0 degrees. Comparing between the blue and green plot also shows the additional pole caused by the 520 pF input capacitance at around 600 kHz (This cutoff frequency is exactly as calculated with the equation shown after the following paragraph). As a note, to acquire the open-loop gain AC response with LTSpice, I used the method shown in this video.

As explained in an article by Texas Instruments on Op amp stability and input capacitance, adding a feedback capacitor can create an open-loop zero that can compensate for the input capacitance pole. The equation describing the open-loop gain AC response with both input and feedback capacitor is rewritten below:

$$ A\beta = \frac{a R_{G}}{R_{F}+R_{G}}\frac{1+sR_{G}C_{in}}{1+s(R_{F}||R_{G})C_{F}}$$

Inserting the following values to the above equation,

$$C_{in} = 520 pF, R_{G} = 1 k\Omega, R_{F} = 1 k\Omega, C_{F} = 520 pF, $$

yield the pole and zero to completely cancel each other:

$$ A\beta = 0.5a\frac{1+\frac{s}{2\pi(306k)}}{1+\frac{s}{2\pi(306k)}}$$

When I plot the open-loop gain AC response with the component values listed above:

The pole at 300 kHz (originally at 600 kHz) really is gone, keeping the slope at -20 dB/decade at around that frequency. However, there seems to be another pole introduced at around 50 MHz, causing the phase margin to drop to around 0 degrees again and decreasing the slope at high frequencies from -40 dB/decade to -60 dB/decade.

So my question is: Where does this additional pole come from? Why is it that it doesn't show in the equation above?

P.S: Yes, I can find a value for the feedback capacitor that improves the phase margin of the original circuit by sweeping the feedback capacitor value, therefore I don't have any knowledge of why it works, which I want to find out.


texts: Why does modern bluetooth audio need lossy compression?

texts:
I understand why Bluetooth has issues with latency, but what is unclear to me is why we're still using lossy compression codecs for it. The latest state-of-the-art (at least according to the marketing department) is aptX-HD, which totally doesn't make sense to me. It's still lossy, yet instead of trying to get closer to lossless it rather adds 24-bit sounds which is, for the most part, useless to the consumer.

Meanwhile, full CD-quality sound uses about 176KBytes/s (or about 1.5MBit/s) which is well within reach of modern Bluetooth speeds. Why doesn't anyone do that, which, I think, would be much more meaningful for sound quality.


texts:
https://www.circuitlab.com/circuit/mthven79a2m6/led-controller/
I designed a LED controller to turn the led on/off. What do u think about my design?


texts:
This is my first ever PCB layout design. I did this in EAGLE and I'm looking for some feedback. Note that this is my first ever PCB layout so I don't know any "rules of thumb". The circuit is simply a MOSFET Half-Bridge driven by IR2113. I've also included the schematic.

Here is a link to the first version of the board.

Here is a revised edition of the PCB layout. I made sure all 90 degree corners were now 45. My only concern are the T-junctions - are they a bad practice? If so, what should I do about them?

Secondly, X1-1 (towards right of the board) is Vcc and X1-2 is the Ground. X2 is the output from the Half-bridge. These connecters are just simple Screw Terminals. X3 is the input to the High, Low and SD pins of the IR2113. I intend to connect these to a AVR microcontroller. LED1 and LED2 serve to indicate which MOSFET is active, as its just a demo board that I'm making to see how successful I am in understanding how the Half-bridge works. Later on, I'll expand this to a Full-Bridge (or it better to that I create the Full-Bridge before I make a Half-bridge?)

I will be etching the PCB myself using Ferric Chloride. Considering this, do the track widths now seem more reasonable?


texts:
I am making a temperature control system using an Arduino. However, I have a problem with controlling a power resistor (which is used as a heater). I was suggested to use a MOSFET to control it. Unfortunately, my lack of knowledge about MOSFETs makes it difficult to do this.

As far as I understand a MOSFET works as a switch which turns ON when there is a voltage applied across GATE pin. When this happens, the resistance between DRAIN-SOURCE is  reduced which allow current to flow. Which is nice, as I need current to heat my resistor.

If I control the PWM signal sent into the MOSFET from Arduino, does this control the current which flows through the heater?


texts: Solar powered mini water pump: how to turn it on/off automatically

texts: I have acquired a mini water pump (5V 1.0A) and several solar panels (each: 5V 200mA). What I try to achieve is to pump water from a container above a vertical hydroponic system and let it flow down back to the container while watering the plants inside. I want to pump the water only for ca. 3-5 minutes each hour during the day. Pumping non-stop during the whole day is not good for plants and unnecessarily wear out the pump. What is the simplest/cheapest way to interrupt the pump most of the time and power it only for 3-5 minutes during the daylight?


texts: For a first order system, what type of response to a sine wave?

texts:
If I put a sine wave through a first order system and reconstruct it with some type of weighting (equal or not), how should the response come out?

Should the response follow the original sine wave almost perfectly, or should it not reach the peak amplitude of the input?

I'm thinking it shouldn't follow the original perfectly since there's a time constant required to reach the peak?


texts: Short circuit protection of lithium pouch cells in parallel

texts:
I want to put together a battery pack with 2 or 3 lithium pouch cells (for example SLPB11543140H5) in parallel, and a few more in series. Of course they have to have some kind of short circuit protection.
In the pdf linked above, the manufacturer mentions a tab fuse. After asking the manufacturer directly about it, this seems to be just a removeable tab, not a fuse.

What would be the right strategy to do this?

With cylindrical cells most people (TESLA for example) use a thin wire which is welded directly on to the cell and the busbar which then acts as a fuse. However this is not possible with the tabs of pouch cells.

Is there a commmon way to achieve this?


texts:
The RTC module ZS-042 get suddenly reset and show default values (2000/0/0) with no possibility to change it no matter what. The reset can occur after uploading a new sketch (I'm using ESP32) or while running.

Just after I unplug the module from ESP32, reconnect it (SCL, SDA, VCC, GND) and upload new sketch it's back to operate normally.

The reset looks like:

The code:

#include <Wire.h>
#include "RTClib.h"
#include "WiFi.h"

const char* ssid     = "****";
const char* password = "*******";
const char* ntpServer = "pool.ntp.org";

RTC_DS3231 rtc; //class RTC_DS3231

char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"};

void setup () {

  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.printf("Connecting to %s ", ssid);
  delay(1000);
  Serial.println("");

  configTime(0, 0, ntpServer);
  setenv("TZ", "IST-2IDT,M3.4.4/26,M10.5.0", 1);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("CONNECTED!");

  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }
}

void loop () {
  DateTime now = rtc.now();

  Serial.print(now.year());
  Serial.print('/');
  Serial.print(now.month());
  Serial.print('/');
  Serial.print(now.day());
  Serial.print(" (");
  Serial.print(now.dayOfTheWeek());
  Serial.print(") ");
  Serial.print(now.hour(), DEC);
  Serial.print(':');
  Serial.print(now.minute(), DEC);
  Serial.print(':');
  Serial.print(now.second(), DEC);
  Serial.println();

 if (touchRead(15) < 10)    // touch pin 15 to update time & date
 {
  struct tm timeinfo;
  getLocalTime(&timeinfo);
  int day = timeinfo.tm_mday;
  int month = timeinfo.tm_mon + 1;
  int year = timeinfo.tm_year + 1900;
  Serial.println(day);
  Serial.println(month);
  Serial.println(year);
  rtc.adjust(DateTime(year, month, day, timeinfo.tm_hour, timeinfo.tm_min,
  timeinfo.tm_sec));
  // begin Transmission with address 0x68 (DS3231_ADDRESS)
 }

 Serial.println();
 delay(1000);
 }

I'm using CR2032 3V and connect it to VCC=3.3V of the ESP.

I read that maybe the supply voltage is not sufficient but I'm not sure because usually it's work fine till the sudden reset occur (can occur once in a two weeks or more). I tried to connect VCC=5V without the battery and still the same problem (get reset once in a while).


texts:
I'm using a CD4060B counter/oscillator and need to know the internal timing of the RESET operation. TI's 4060B datasheet says that the minimum input reset pulse width is 30 ns at 10 V, and the reset propagation delay is 80 ns.

When calculating the time for a RESET does the propagation time start after the minimum Reset pulse width?  Then is the output transition time of 50 ns added for a complete reset operation?


texts:
I am using an ESP32 (any microcontroller will be the same) to turn on/off an aquarium heater with a 220V relay (rated at 10A, with an octocoupler driven by a GPIO pin on Arduino, it's a small PCB that came from e-Bay.)  The relay is a mechanical type.
The board looks like this:

 Source: https://ae01.alicdn.com/kf/HTB1aXS2B8mWBuNkSndVq6AsApXaS/5-v-1-Un-Canal-Module-de-Relais-Bas-Niveau-pour-Contr-le-D-appareils-M.jpg
The heater is rated @ 500W.
Sometimes when the relay kicks in, the home safety switch kicks in, and shuts down the power in the house.
This doesn't always happen.
I have double checked the wiring, and everything seems correct.  I also tried with an electric bulb (a standard socket bulb paired with a 9w led bulb, I don't have any old type bulb) and with 10-15 simulations it never happened. With heater it happens every 5-6 times.
My quess is that that relay + high power device doesn't work well.
I read that an RC snubber should help in this case, putting it in parallel with the socket driven by the relay.
Is that correct?
Can also someone explain me why this happens, just to better understand the cause?

I add a little schema on how it's wired all togheter, the L/N mean live/neutral, i can't know what got plugged into the wall (i can test it, but i can't guarantee someone doesn't plug/unplug it).   the heater have 2 pin, not connected to GND, it's a standard glass aquarium heater, sealed with resistor inside the glass pipe like this one
https://www.acquariomania.net/web/image/product.template/11829/image


texts:
I am using a RCS-Model-M2313 R/C Servo and I have managed to create a PWM. My problem is that my motor doesn't react as I was expecting. I would like to control the motor angle with the duty cycle but it doesn't work.
Indeed, with a 28% duty cycle, a 550 Hz frequency, 1.7V offset, a 3.3V signal from my MCU I can control it to come back to the same position. I have powered the servo with a 3.7 tension.
When I change the duty cycle, the motor turn but doesn't stop anymore.

The datasheet doesn't give any information, I really need your advices.
Thank you.
Regards,
Mattew


texts: Push-pull configuration using ZXMC4559DN8TC

texts:
I'm testing this circuit and I found some issues in driving ZXMC4559DN8TC n-p channel MOSFET.

simulate this circuit – Schematic created using CircuitLab

I have some problem in driving ZXMC4559DN8TC. PWM signal is correct at the gate of the ZXMC4559DN8TC. On the output load there is always 15V (even if a keep low PWM duty cycle). Am I missing something?


texts: Run 15A 120VAC HeatPress on 15A outlet, limit current to 12A (limiter boxe???)

texts:
I want to limite the amount of current a appliance could draw to 12A in order to use it on a 15A outlet without tripping the breaker.

I have a HeatPress (heating element(coil) with a PID controller) working on 120VAC rated 15A with a T-Brace plug for 20A outlet.
Link to Heatpress website spec

The previous owner told me he add a electrician make him a adapter cable with a box in the middle to be able to plug in it a 15A outlet without tripping the breaker.(but it was nowhere to be found)

I think I must keep the voltage to 120V to make the PID and maybe other electronic component happy so I dont think a variac can be the answer.

Common theorical sense told me to raise the resistance from 8Ω to 10Ω

120V 15A 8Ω 1800W   /   120V 12A 10Ω 1440W

But adding in serial a 2Ω 1440W if I'm right sound in my head like a joke.

So here I need your help, what was in that boxe? Is it possible to limit the current the appliance can draw?
I know the heating element will take more time to heat and wont be able to be as hot but that's not a problem for me.

Thank You for you time

Sam


texts: What does the multimeter dial do internally?

texts:
Everyone who has ever handled a multimeter is familiar with these dials. The position of the dial indicates the maximum range of the quantity that can be measured.

But why are we required to adjust the maximum range ourselves? What happens internally in the multimeter when the dial is adjusted, say, from 20V to 200V? If we have the dial on 20V, and the voltage measured is 50V, why can't the meter provide a measurement? I don't have much knowledge on the internal workings of a multimeter, but I understand that voltage is measured by letting an infinitesimal amount of current through the meter and measuring the magnetic field (something along these lines). But why can't the meters adjust their range themselves?

EDIT: I know there are autoranging meters, but I'm interested in knowing why others have to be adjusted manually.


texts:
I am not an electrical engineer but I was just reading the book - The art of electronics. I am just a bit confused about how to analyze this amplifier circuit.
In this case, why are R1 and R2 in parallel?
I would think it makes more sense for R1 and Rc to be in parallel. Even if that is not the case, when we look into the circuit, shouldn’t there also be a large impedance due to the gain of the transistor? Thanks in advance.


texts: How is electricity from a power station added to the grid?

texts:
If I construct my own solar powerplant to add my output to the power grid how is it done technically ?

What are all the steps I need to go through ?  (Not regulatory procedures.. But would still be interesting to know)

For example, If I filter water at my water treatment plant I can connect my pipeline to the water network of the city. I'm guessing it might not be so simple with electricity ?


texts: Increase instead of dip in voltage in a AC to DC Motor Circuit

texts:
I have a very simple circuit. 120 AC into a rectifier output to a 120 DC motor. No caps or resisters. Literally a rectifier a DC motor with a thermal protected. No more no less.

When I power on the voltage at the outlet goes to 165 and stays there until power down.

Cannot figure out the cause. Any ideas?


texts: What are the efficiency limits of the Peltier effect?

texts: I understand that thermoelectric coolers are perhaps a quarter as efficient as heat pumps. Why? What is the source of this efficiency limit? What would have to change for thermoelectric coolers to be more efficient?


texts: PIC MCUs C language Compilers and IDE for PIC16F and PIC18F

texts:
I want to write some program in C language for a PIC16F and a PIC18F. I searched in the internet and I got confused with the name of them! I want a free version and I know that my C program is less than 2 KB. Does MPLAB lonely enough? Or I need to install C16? C18? Which one I must install? Can I install both in a single computer?

I found four kind of MPLAB C18 Compiler here.I don't know which one should I use and what is the difference?

Is there any other free software that is better for a beginner? and also be good for biggish project?

And finally what is the difference between MPLAB IDE and MPLAB X IDE and these different CXs (C18 C24 ...)?

Finally please give me a full view about the advantages and disadvantages of different PIC compilers.
And give me a good tutorial source about installation steps and the steps to build a simple flashing LED with PICs for step one to getting started with this kind of MCUs.

Note that I am familiar with AVRs and I worked with them about 1 year.


texts: How this servomotor calibration is supposed to work at electrical level?

texts:
Here is the Wiring Diagram:

I am trying to understand how this servo motor calibration process (see screenshot of BMW software) is supposed to work at electrical level. In particular:

there is 2-pin classification resistor attached to the servo - What does it do? Does it measure something? How to know if it is good?
what are IMP, SM_A, SM_B, BR and DIR pins on the servo harness?
is there a way for me to somehow test if servo motor is up to its specification by testing it outside car?

For more context, that is a transfer case servo motor (aka VTG actuator) that engages clutch pack in BMW X3 ATC400 transfer case that distributes torque between front and rear axles. Few months ago I replaced a completely worn off plastic gear (not visible in the video below) in the servo motor and was still able to calibrate it successfully. However, few days ago the car was shuddering at slow, sharp turns. So I decided to disassemble servomotor the second time to lube up the gear with grease. Now the calibration consistently fails.

I took the servo motor out of transfer box and I can see that the gear is able to spin with no load. So it is not like servo motor is completely dead. Few members on BMW forums suggested that they replaced the servo motor to solve the issue.


texts: Wire gauge and combined wires for 3D printer hotend through PCB

texts:
So I've been designing a wiring harness PCB for my 3D printer to provide connections and easily swappable tools.  I settled on a TE 34-pin connector to use as input on the PCB.  The current design includes everything I need for any of my tools except the heater cartridge for the hotend.  Everything is running over 20awg stranded copper wire.

My concern for the heater cartridge was that, despite 20awg being able to carry the <2A load, the fact that the heater cartridge relies on resistance in the cartridge to heat up, I wasn't sure how that would equate to usability of the 20awg and requirements for my PCB traces (if there's any change at all given the amperage for any other use).

So, my questions are:

Should I pair 2x 20awg wires for each of the nominal leads of the heater cartridge, or would a single wire on each side work fine?
Given that the use end of the circuit is designed for high resistance, will the PCB traces need to be wider for any reason? Would the connectors on the PCB need additional thermal relief at all?


texts: Different voltage solar panels in parallel

texts:
I'm using a solar panel to power an Arduino + a LiPo battery charger. I'd like to increase the amount of current at the same voltage, so would like to wire up a second solar panel in parallel to the current one.

The panels are slightly different:

https://www.sparkfun.com/products/7840
http://www.adafruit.com/products/500

One is a 6V; the other an 8V.

Assuming my charger can take the voltage (it can), is there anything special I need to do to wire these in parallel? Do I need blocking diodes on both?

EDIT: I'm reopening this because putting these panels in parallel did not work. I'm certain of the wiring, and each individual panel works fine, but putting them together drops the voltage down to <1V. I'm assuming the voltage imbalance is creating some kind of issue. Is this something that can be addressed with additional (simple) circuitry, or should I just buy another matching panel?


texts:
Apologies in advance if this has been asked before, but I haven't been able to find anything like it. Please let me know if it has.

I'm curious about the proper/standard way to connect a SPDT switch in a digital circuit. Below are two potential configurations for connecting a high/low signal to a digital pin-- which is better? Are neither of them preferable?

I know the first can use a simple SPST instead of the switch I used; I'm more concerned with the wiring principles. Is it sensible to leave a power signal "floating", like in the bottom configuration, or does it not matter? Should a pull up/pull down resistor configuration be used instead?

Thanks a ton!


texts: Multi level logic in transistor level. Possible?

texts:
I am currently studying the MOSFET transistor for Digital CMOS IC design. There, the noise ratio is defined and the 50% margin is assigned for a logic HIGH and LOW.

Taking the noise into account, do we have enough room to differentiate 4 level voltages(logic level) in transistor?

So we can achieve four logic levels: 0, 1.25v, 2.5v, and 3.75v

Therefore : Invert(0) = 3.75 and Invert (1.25) = 2.5v


texts: What is the purpose of the large resistance from gate to drainin this MOSFET circuit?

texts:
In the circuit below, what is the purpose of the very large resistance (\$5 M \Omega\$) between the MOSFET gate and drain terminals?

I have seen circuits before which have a connection between the gate and the drain of the device called enhancement mode devices which can act as non-linear resistors. Is the circuit above related in anyway?


texts: Wi-Fi transmitter/receiver in close proximity: Override interference?

texts:
I'd like to control a camera via Wi-Fi (zoom, trigger shutter, etc.), and possibly also capture a live video stream. This will be at an event with a huge number of Wi-Fi devices, and connectivity is expected to be unstable.

Could I just place the antenna of the device that I use for controlling the camera right next to the camera, to override any interference from other networks?

(Unfortunately, the camera cannot be controlled via a wired connection, e.g. USB, or else I'd use that.)


texts: How do I send accelerometer (ADXL335) signals (x, y and z) via xbee?

texts:
I want to send the signals from a 3 axis accelerometer (ADXL335) to a PSoC3 via Xbee modules (S2).

What configurations do I need for each Xbees and can I send each of the signals (x, y and z) directly? If yes, then how? Would I need a separate microcontroller to convert analog signals to digital signals, or are the ADCs on the Xbees sufficient to do the job?


texts: Simple Efficient Cost-Effective DC-DC Converter Circuit?

texts:
Is there a switched-mode DC-DC conversion circuit that makes it easy to configure different input/output voltages?

Circuits given on the datasheets of the LMR12020 and others have a large number of discreet components in certain combinations. Is there a much simpler circuit that is:

easy to configure output voltage (using standard components)
>= 90% efficiency [edit: 80% is fine]
inexpensive in production (BOM under $5)

Example Configurations:

9-20V -> 14.4V (or 15V) @500mA  [to charge lead-acid battery]
10.5-15V -> 12V @500mA
5-15V-> 3.3V @100mA

What are some inexpensive solutions with straightforward calculations to set the output voltage?


texts:
I'm just confused about relays. For example, say for something like this
https://uk.rs-online.com/web/p/latching-relays/0515571/
It says coil voltage is rated for 12VDC and switching current of 5A. Does that mean that to close the relay (turn power on), I have to apply 12VDC across two of it's terminals and as soon as that 12VDC is gone, it turns off?
Or does that mean, I have to apply 12VDC to turn it off?

Also, what does the switching current mean?


texts: How to get raw emg signal without offset

texts:
i try to build emg sensor + arduino from diy found on internet.
every things work fine, but i want only raw signal for some bigger project not rectify. i do circuit  as below

and signal looks like

as you can see when it reaches value 0 it stops. i try to get some real raw signal and modify code, but nothing change, so i think it's hardware. any guess how to remove this offset ? configuration of tl072 should be different?


texts: Generating a delayed pulse with one 555 timer upon powering up the circuit

texts:
This is a very beginner's question - I apologize if this is some trivial extension of a known practice.

Can I use one 555 timer without any extra transistors/IC to generate a delayed pulse as shown below upon powering up the circuit?

The intended circuit has no buttons or other external triggers. It is activated by being suddenly connected to power (from z-wave smartswitch) and is supposed to:

after power up, keep output pin low for ~15 seconds
put output pin to high for ~5 seconds
finally, put it to low and keep it there forever

This probably can be done easier with two 555 timers but I think that one 555 timer should be able to do it as well. This is also a great learning experience in understanding the mechanics of 555.


texts:
I should get i(t) on PSpice.

I tried doing it by writing the following code:

VIN 1 0 SIN(0 2 18.8495 0 0 60)
R1 1 2 2
C1 2 3 0.33
L1 3 0 1
R2 3 4 2
C2 4 0 0.166
VP 4 0 0
.OP
.END

The output is:

NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE

(    1)    0.0000  (    2)    0.0000  (    3)    0.0000  (    4)    0.0000

    VOLTAGE SOURCE CURRENTS
    NAME         CURRENT

    VIN          0.000E+00
    VP           0.000E+00

    TOTAL POWER DISSIPATION   0.00E+00  WATTS

All voltages are 0s, and I think it should not be.

Thanks

EDIT:
I tried this, using phasors. I calculated 0.47A for i(t), but I get 1.000E-30 on spice

VS 1 0 AC 2 60
R1 1 2 2
C1 2 3 0.33
L1 3 0 1
R2 3 4 2
C2 4 0 0.166

.AC LIN 1 18 18
.PRINT AC I(C2) IP(C2)


texts:
Assuming that:

\$\beta=200\$

\$|V_{BE ON}|=0,6 \,V\$

\$|V_{CE SAT}|=0,2\,V\$

\$r_0=50\,k\Omega\$

\$c_{\pi}=4\,pF\$

\$c_{\mu}=4\,pF\$

How can I calculate the quiescent point of each of the transistors?
I need to know and DC voltages on all nodes and \$I_{CQ}\$ and \$V_{CEQ}\$ of both transistors. Can you help me, please?

Note: The two floors must be analyzed simultaneously, they can not be analyzed separately.

Without capacitors:

Small-signal equivalent circuit for mid frequency:

For the first transistor (Q1):

\$g_m=\frac{I_{C1}}{V_T}=\frac{1,446\times 10^{-3}}{25\times 10^{-3}}=57,84\,mS\$

\$r_{\pi}=\frac{\beta V_T}{I_C}=\frac{200\times 25\times 10^{-3}}{1,446\times 10^{-3}}=3457,81\,\Omega\$

\$r_0=50\,k\Omega\$ (teacher gives this number to us)

For the second transistor (Q2):

\$g_m=\frac{I_{C1}}{V_T}=\frac{5,50\times 10^{-4}}{25\times 10^{-3}}=22\,mS\$

\$r_{\pi}=\frac{\beta V_T}{I_C}=\frac{200\times 25\times 10^{-3}}{5,50\times 10^{-4}}=9090,9\,\Omega\$

\$r_0=50\,k\Omega\$ (teacher gives this number to us)

Calculation of \$R_{out}\$, \$R_{in}\$ and \$A_V\$:

For the first transistor:

\$R_{out}=r_0//R_1=\Big(\frac{1}{50\times 10^3}+\frac{1}{6,8\times 10^3}\Big)^{-1}=5985,92\,\Omega\$

\$R_{in}=R_g+R_4//r_{\pi}=1\times 10^3+\Big(\frac{1}{270\times 10^3}+\frac{1}{3457,81}\Big)^{-1}=4414,09\,\Omega\$

\$A_V=\frac{v_0}{v_i}=\frac{-g_m v_{\pi}R_{out}}{v_{\pi}}=-57,84\times 10^{-3}\times 5985,92=-346,23\$

For the second transistor:

\$R_{out}=r_0//R_2//R_L=\Big(\frac{1}{50\times 10^3}+\frac{1}{4,7\times 10^3}+\frac{1}{10\times 10^3}\Big)^{-1}=3005,12\,\Omega\$

\$R_{in}=R_1//r_{\pi}=\Big(\frac{1}{6,8\times 10^3}+\frac{1}{9090,9}\Big)^{-1}=3890,16\,\Omega\$

\$A_V=\frac{v_0}{v_i}=\frac{-g_m v_{\pi}R_{out}}{v_{\pi}}=-22\times 10^{-3}\times 3005,12=-66,11\$


texts:
I am in the phase of debugging a PCB with several chips on it.
I currently realize that during PCB design some strategies for easy debugging later on should be implemented.

Personnaly, I just realized the importance of placing test point (on power rails and on signals to monitor such as communication interface (SPI, I2C, UART) or reset pin, R0 resistor/jumpers to isolate circuit group to make some unit testing, and ading some small leds onpower rails to quickly identify if power is disributed on power rail or not.

I am quite sure there are other strategies to implement.

Can you share what other usefull design strategies do you implement when you are designing your PCB ?


texts: Boat Auxiliary battery - this simple ok?

texts:
I have feared running out of battery voltage to start the boat engine after running the electronics with the engine off. Would something as simple as this figure work? Obviously both are 12V. Main is deep cycle lead acid and aux battery would be smaller lead-acid. When the electronics die, i would know to start the engine and flick the switch on and start charging both again.

I have seen battery isolators - but that seems overly complicated for this application? I suppose it would eliminate the need for a manual switch and remembering that. If i dont flick the switch off when the engine is off, then i would drain both batteries.

Thanks for any ideas guys.  Neil


texts:
So i've been learning about boost converters, and it makes sense. From what I understand in the schematic below when the switch closes the inductor receives a large amount of current (since we have no load). So the current shoots sky-high (don't want to leave the switch closed too long!)

So once we open the switch, the voltage rises because the inductor resists the change in current, so the voltage goes higher to resist this (I still get confused on "why".....I wish there was a good "water" analogy for it)

So switch opens back up, the voltage is higher while the magnetic field collapses. Lets pretend the supply was originally 10v, and doing the switch open/close/open brings it up to....20v for instance.

Is that permanent? I mean lets pretend the "load" was a capacitor for instance, would it store 20v? I mean surely the inductor can't be keeping it at 20v forever right?

Also side question, if you had a super strong capacitor for the "load" could you store that high voltage in it? (like lets pretend we had a 200v capacitor) could you store 200v in it and then release it somehow like a HUGE charge all at once? (obviously it would be a bad idea ofc)

Thanks!


texts: Solar Panel Voltage vs. Consumer Solar Generator

texts:
I have a 235 W solar panel that I wish to take with me on camping trips. I’m looking at getting a Goal Zero “solar generator” product to store the energy from the panel, specifically the lithium-ion versions. The battery (Yeti 1000 and Yeti 1400) is rated on the spec sheet as being able to take input of 12-22 V. The Voc of the panel is listed as 37.06 V.

Does the charge controller in the battery allow me to connect higher voltage panels and automatically lower it to match, or are these products incompatible? If so, what will the compromises be?

Assuming I want to use the battery, and want a 200+ W portable panel(s), what are my options? I just want the biggest solar panel(s) that I can fit on the roof of my car.

Thanks and sorry if this question isn’t in the scope of this section of StackExchange. I did search other questions.

Edit: links to products.

Panel (235):
http://www.suniva.com/documents/MVP60Cell_022912.pdf

Battery:
https://www.goalzero.com/shop/power-stations/goal-zero-yeti-1000-lithium-portable-power-station/


texts: Do I Need Receptacle or Crimp Terminal with Header?

texts:
I am considering to use Molex Nano-Fit Connector however i have never used it before. I will use it on a PCB Board and i am thinking to use only vertical header. I just desire to connect my cables to board. Is the Vertical Header enough or do i need Receptacle Housing or/and Crimp Terminal? For example when i connect the cables to my PCB circuit with 1053091104 vertical header, do i need also receptacle 1053071204 and/or Crimp Terminal 1053001100?

Thank you so much.


texts: Driving Multiple LEDs with the Help of Shift Register

texts:
I am using this Shift Register.

My circuit is the same as the Figure 14 in the datasheet.

I am trying to understand how the data flows from the MCU Serin, Serout lines and how the LED are driven.

The data transfer speed is 1Mbps.

Suppose, we send a bit stream from the MCU like 0s and 1s, and some LEDs turn ON and some are OFF. After sometime, a different LED is turned ON, the bit pattern from the MCU to the shift regsiters are changed right? At that time, the already Glowing LEDs might turn OFF for an imperceivable time and get back ON? Is my understand correct?

If not, please let me know how the data flows completely from the MCU, to the shift register and the Back to the MCU via Serout line. (Serout is then fed back to an MCU pin)

I have less understanding of Software coding. Please explain in simple terms.


texts:
I was finally able to buy a used Toshiba T4700CT to play my DOS games. I cleaned it, disassembled it and replaced both the backup battery and CMOS battery, but I have a question regarding the main battery.

It is a totally dead 12V NiCad battery, I was wondering if I could replace it in some way, but I wasn't able to find a valid replacement.

I read that you can't replace it with a lithium battery as the charge process is not compatible.

Would you please suggest me what would you do in this case?


texts:
I have a Spartan 6 FPGA (XC6SLX9-2TQG144) and I'm designing a power supply for it.

Let's assume that I will utilize all of its logic (very possible) and I want to clock it as fast as possible (around 350MHz).

How can I estimate the power (number of amps) that my PSU has to supply? Not precisely, but just an order of magnitude. 1.2 V for core and how many amps? 3 A? 5 A?

Side question: is sequencing of power supplies neccessary for this Spartan?


texts: How to control 220v ac lamps using 5v dc safely

texts:
I want to control 10 devices using arduino. I tried to use a 2N2222 transistor and 1N4001 diode with a 240V 10A relay for each lamp, but sometimes it doesn't work good. And I want to make it more efficient, so what can I add to make it more powerful to stay working for 24hours safely for all of the components specially the arduino? I have read before that I can use a comparator to give the transistors the exact voltage to the base and also I read about optocoupler that can be added to make it more safe, but I don't know how could I connect the optocoupler to the circuit.

How can I improve my circuit to take its input from arduino exactly as it wants to make the relays work very good and makes the circuit safe from any bad circumstances?
Is there any suggestions to control this 10 lamps or more ?


texts:
I'm trying to implement a 3-bit counter using basic gates (AND, OR, XOR, NOT etc..) around 3 D-type flip-flops. The input is an increment signal that when set to 1 will allow the counter to increment by 1. There are 3 outputs count(0), count(1) and count(2) where count(0) is the lsb.

But I'm not sure how can I handle the set in D-type flip-flops.
I have illustrate as follows but you can find there is set port in DFF.
So How can I make set in verilog? I'm not sure is this meaning reset? if yes, what if set is 1, is meaning negative reset? or positive reset?

How do I modify as above rule (the input is an increment signal that when set to 1 will allow the counter to increment by 1)? Am I interpreting it right or wrong?

UPDATE:

Is this the same thing?

always @ (posedge clk or negedge reset )
if(set)
    begin
      Q<=1'b1;
    end

UPDATE:

   wire q0;
   wire q1;
   wire q1_i = (q0 ^ q1);
   wire q2;
   wire q2_i = (q2 ^ (q0 & q1));

   dar u_dar1 ( ~q0 , clk , reset_n, q0);
   dar u_dar2 ( q1_i , clk , reset_n, q1);
   dar u_dar3 ( q2_i , clk , reset_n, q2);

   wire [2:0] rere = {q2,q1,q0};

   module dar  (
                   data  , // Data Input
                   clk    , // Clock Input
                   reset , // Reset input
                   q         // Q output
                   );
   input data, clk, reset ;
   output q;
   reg q;
   always @ ( posedge clk or negedge reset)
           if (~reset) begin
             q <= 1'b0;
             end  else begin
               q <= data;
               end

   endmodule