texts: 1.2V, 3.3V, and 5V small power supply design

texts:
Problem:

I'm attempting to develop a power supply for a system that needs 1.2V, 3.3V, and 5V from mains 120V 60Hz. I have never ran into needing all three at once and am curious if anyone knows of a more simple/smaller solution then what I'm proposing.

Attempt:

I'm considering using a buck regulator SMPS to obtain the 5V from 120V and 2 linear regulators. First regulator to step the 5V down to 3.3V and then the next one to step down the 3.3V to 1.2V. Being that size is a big issue I'm up to hear some ideas.

Side note: The total current draw of 3.3V is no more then 1.0A and total current draw of 1.2V is no more then 1.0A.

Using some of the comments and answers, I went out and found this IC BA3259HFP. Any thoughts? It appears to solve the issue with 5 pins, 3 caps and 2 resistors.


texts: Use of ground symbols in circuit diagrams

texts:
In this question is the following diagram for a voltage booster intended for small battery powered devices

The TPS61200 spec says GND is control/logic ground and PGND is power ground but this isn't reflected in the symbols chosen in the diagram. I'm also puzzled why the link to earth is shown on GND rather than on PGND.

From this key it seems that various parts of the above circuit are to be tied to chassis ground and not to (say) digital/common/signal/control/logic ground.

Why specify chassis ground? Am I wrong in interpreting that as the metal part of an enclosure which is (usually) tied to earth through the mains electrical connection for safety purposes.

I have looked at similar questions here† but am still puzzled by the choice of symbols on the example circuit.

Why are these particular symbols used in this circuit diagram?

† Related questions

Schematic symbol confusion
How is the following ground symbol different from conventional ground?
Ground question


texts: How to convert 8080 type 8 bit parallel interface to I2C interface?

texts: I have a 8080 type 8-bit parallel interface LCD. Is it possible to convert it to I2C interface?


texts: Understanding Two MOSFET with sources connected

texts:
I am having problem understanding how this MOSFET configuration (used in battery charger) works?

In this slide,

 what does it mean "blocking voltages in both directions while allowing bidirectional current"?


texts: How does mechanical absolute encoder work?

texts:
I want to know more about this kind of encoder, but I can't find any source (other than wikipedia), where I can get more details about it. Can anyone explain or point me to a source where I can read about it?
I want to understand the working principle of mechanical absolute encoder.


texts: Create a continous variable force on object

texts:
I have a component that I need to press to another component with ideally max 200 Newton of force. I want to be able to to control this force. E.g I should be able to have half the force or 1/10 the force.

I only need a very small amount of travel. 1mm would already be enough. My idea is to use a linear solenoid like this one. And the control the current to control the force the solenoid provides. Another solution I thought about is to use a bar a holding magnet like this
one and use a permanent magnet to on the other side to create repulsion between the holding magnet and the holding magnet if I power the holding magnet. However the force a bit too low.

I have never used solenoids before and I wonder if there is some alternative that might work better for my case. I don't really have much room so large solutions

Any help is appreciated!


texts: I want to attenuate my incoming signal whose value is around ±80V to ±0.8V

texts: I have used this circuit configuration to attenuate the signal. Will this work without clipping the signal? Is there any alternative to this? I have to give signal to ADC as a input whose input voltage signal span is 2 Vpp.


texts:
Let me start by saying that I'm pretty new to electronics, so be gentle ;)

I'm able to get good, solid tones from my piezo when nothing else is connected. When I connect it alongside my servo + keypad, the tones are so quiet that I can't hear it unless I get really close to it. I'm assuming that the piezo isn't receiving enough current, but I don't know if that assumption is correct, or how to fix the issue.

The piezo plays a tone on each press of the buttons on the keypad. Once the correct combination has been entered, the servo is attached, moved 90 degrees, then detached, and the LEDs change from red to green.

Here's my build:

Schematic:

Parts:

Servo: Micro A0090 Sparkfun product page
Piezo: CEM-1203 Datasheet

Function called for playing tones:

void playTone(long duration, int freq)
{
  duration *=1000;
  int period = (1.0 / freq) * 1000000;
  long elapsed_time = 0;
  while(elapsed_time < duration)
  {
    digitalWrite(pinSpeaker, HIGH);
    delayMicroseconds(period / 2);
    digitalWrite(pinSpeaker, LOW);
    elapsed_time += (period);
  }
}

Called on keypress:

playTone(750, 500);

Full code:

#include <Servo.h>
#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 3;
const byte PINLENGTH = 4;
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {5, 4, 3, 2};
byte colPins[COLS] = {8, 7, 6};

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

char PIN[PINLENGTH]={'2','5','8','0'};
char attempt[PINLENGTH]={0,0,0,0};
int z=0;

Servo lock;
int pos=0;

int pinSpeaker=11;

int redLED = 12;
int grnLED = 13;
boolean armed = true;

void setup()
{
  pinMode(pinSpeaker, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(grnLED, OUTPUT);
  Serial.begin(9600);
  resetLock();
  Serial.println("* SYSTEM ARMED *");
  Serial.println("  Ready...");
}

void resetLock()
{
  lock.attach(9);
  for(pos=20; pos>0; pos-=1)
  {
    lock.write(pos);
    delay(15);
  }
  lock.detach();
}

void closeLock()
{
  lock.attach(9);
  for(pos=lock.read(); pos>=1; pos-=1)
  {
    lock.write(pos);
    delay(15);
  }
  lock.detach();
}

void openLock()
{
  lock.attach(9);
  for(pos=lock.read(); pos<100; pos+=1)
  {
    lock.write(pos);
    delay(15);
  }
  lock.detach();
}

void correctPIN()
{
  armed=false;
  playTone(750, 2500);
  openLock();
  Serial.println("* SYSTEM DISARMED *");
  Serial.println("  Ready...");
}

void incorrectPIN()
{
  playTone(750, 1000);
  Serial.println(" * Incorrect PIN *");
  z=0;
  Serial.println("  Ready...");
}

void checkPIN()
{
  int correct=0;
  for (int q=0; q<PINLENGTH; q++) {
    if (attempt[q]==PIN[q]) {
      correct++;
    }
  }

  if (correct==PINLENGTH) {
    correctPIN();
  } else {
    incorrectPIN();
  }

  for (int zz=0; zz<PINLENGTH; zz++)
  {
    attempt[zz]=0;
  }
}

void readKeypad()
{
  char key = keypad.getKey();
  if (key != NO_KEY)
  {
    switch(key)
    {
    case '*':
      if(armed==false){
        armed=true;
        playTone(750, 1000);
        closeLock();
        Serial.println("* SYSTEM ARMED *");
        Serial.println("  Ready...");
      }
      z=0;
      break;
    case '#':
      if(armed==true){
        Serial.print("\n");
        delay(100);
        checkPIN();
      }
      break;
    default:
      if(armed==true){
        playTone(250, 2000);
        Serial.print(key);
        attempt[z]=key;
        z++;
      }
    }
  }
}

void playTone(long duration, int freq)
{
  duration *=1000;
  int period = (1.0 / freq) * 1000000;
  long elapsed_time = 0;
  while(elapsed_time < duration)
  {
    digitalWrite(pinSpeaker, HIGH);
    delayMicroseconds(period / 2);
    digitalWrite(pinSpeaker, LOW);
    elapsed_time += (period);
  }
}

void loop()
{
  if(armed==true)
  {
    digitalWrite(grnLED, LOW);
    digitalWrite(redLED, HIGH);
  } else {
    digitalWrite(redLED, LOW);
    digitalWrite(grnLED, HIGH);
  }
  readKeypad();
}

How can I get proper output from the piezo?


texts: Why do we always implement the complementary of the boolean expression when we design a CMOS circuit?

texts:
I am new to implementing boolean expressions in CMOS form, and I understand that the "C" in CMOS stands for "Complementary", so it is an inverter circuit.
What I don't understand is: All the tutorials say that if you want to design an "AND" gate you have to place the transistors in series if they are nMOS and in parallel if they are pMOS. Why is that?
Why can't we just say "for AND gate: place the nMOS in parallel and the pMOS in series" so that we'll be able to implement the functions directly, without need of an inverter before the output?
Would that create some problem that I haven't come across yet?
I had a CMOS full adder circuit that I had to extract the boolean expression from, and I noticed that the expression I was extracting was correct according to the aforementioned implementation rules, but then I noticed the inverter before the output, and got confused. Is there some logical reason for the rules being like this?
EDIT: In below picture, the OR operation in nMOS corresponds to placing the transistors in parallel. The opposite is true for pMOS. My question is, why did we have to implement the inverse function? Couldn't we have made the circuit directly, using the original function and inverting the "rules" about OR corresponding to nMOS in parallel (making them "nMOS corresponds to nMOS in series" instead)?

(link of video where i got the above screenshot:https://www.youtube.com/watch?v=7XEUB_dTaK0)


texts: how to test isolation of DCDC convertor?

texts: I have an isolated DC-DC convertor which boasts a 1.5kV isolation. I have a PCB made along with the additional components it requires. How can I test it?


texts:
I am curious if anyone knows if a Vishay DG212 works with VLogic being powered by 3v3?

The only test conditions the datasheet speaks of are where VL is being powered by 5v.

Here is the datasheet:
http://www.vishay.com/docs/70040/70040.pdf

The simplified schematic makes it seem like sending 3v3 to VL should be no problem since it is the logic high reference for a MOSFET H Bridge (I think?), but I wanted to ask the community if anyone has any experience using these chips in real life using lower logic levels than specified in the datasheet. I don't have an opportunity to test this out before I build a PCB, so I was hoping to get some real world experience from elsewhere.

V+ and V- in my situation would be powered by 12v rails (just an FYI)


texts:
I am currently working on a Solar powered project but I am having a hard time making it work:

I have a PCB with an Arduino and a sensor, this circuit consumes 250mA for around 2 seconds every 10 minutes and the remaining time consumes less than 1 mA, I am using a simple BJT TIP31 switch to turn off the sensor and sleeping the arduino to achieve this.

For powering this circuit I am using a 6300mAh 4.2V Li-Ion Battery connected to a TP4056 breakout board set to 1000mA and to a 1W 6V Solar cell for charging the battery.

The goal is to keep the battery going infinitely (or at least give it a good lifetime ~a year maybe) by charging it with the Sun

The battery goes in parallel to a AMS1117 regulator and then to the arduino PCB.

Usually the system works for a couple of days at most (never seen more than 5) and dies.

I am sure I am missing something on this design. My bets are the solar cell is not enough at all but also there are whole circuits that run on a single
coin battery for a long time (years) and have a higher power consumption than this one. How can they achieve this?

What do you think it's wrong with this system?

Any pointer in the right direction would be extremely useful. (Papers, previous similar work, researches, maybe changing some components… you name it)

On the top of my head some suggestions I’ve been considering are:

More power in Solar cell (Not ideal because of the size)

Changing the regulator

Maybe changing the battery design to two cells in series to provide more power

Changing to a “smart” charger. I’ve got this at hand but it says it is for LiPO so I am not sure if this will work with Li Ion

Thanks in advance.


texts: Wavelengths blocked by a certain metal mesh

texts:
Introduction: I've heard about a theory, according to which you can check if there is any leakage in your microwave oven by putting your mobile phone inside and call it. However, I gave it a try and the call was successful.

I realized that the two devices are working on different frequencies (and wavelengths, of course), thus the metal mesh in the door of the oven may be unable to block anything different from the intended working frequency. I came across similar results on the Internet.

Calculating the free-space wavelengths for 1.8 GHz and 2.45 GHz, we get ~0.167 and ~0.122 meters, respectively. This means a 40% increase in wavelength for the unintended usage.

Problem: Still, I don't understand why I was able to call my phone. First of all, I vaguely seem to remember a 'thumb of rule', namely that a metal mesh blocks electromagnetic waves of which the wavelength is in the same order of magnitude as the dimensions of the holes (or smaller). Well, that looks absolute stupidity, as the holes appear to be no more than 2-3 mm each side (almost a hundredth of the wavelengths).

Secondly, those wavelengths are practically the same in comparison with the holes.

Question: Given the dimensions of a metal mesh, how can you determine the range of wavelengths blocked by it?


texts:
I'll start by saying that I'm self-taught in electronics, and tend to ask a lot of questions because I don't know NOT to ask them. This is one of those questions.

Consider: I have 120VAC and need 12VDC.

On one hand, I'd get myself a wall-wart transformer that puts out 12VDC and be done with it.

But why a transformer? Why not use a bridge rectifier to get DC, smooth out any ripples with a cap, a throw in a voltage regulator...say a 7812 in this case.

Why is one method preferred over the other? I assume the rectifier/regulator solution would generate a TON of heat and perhaps need a prohibitively large heatsink. Is is engineer's choice? or is there something in the physics that makes one solution is more efficient or cheaper to manufacture than the other? or are there some other crazy unintended safety considerations?

As someone who tinkers and builds stuff, what are some of the considerations in deciding to use a transformer instead of a rectifier/regulator in a project (apart, of course from the why re-invent the wheel when you can buy a wall wart at the corner store argument)?

I'd love to understand this a little better.


texts: Why does the 2nd stage of my MASH Delta Sigma Modulator have essentially no effect on the PSD?

texts:
I've asked about simulating Delta-Sigma Modulators a few times before and have made progress in simulating their design for a project, but I've hit a bit of a roadblock. I'm trying to simulate a 2-2 MASH DSM with a constant input (for PLL applications) in Simulink. I'm just using the single quantizers (and added some offsetting to make them behave as intended, which in this case is making them output a 0 or 1 rather than a -1, 0 or 1). The added -C- (which is just 0.500000000001 or so, so the signum block never outputs 0), 1, and scaling by 0.5 is used to accomplish this.

My issue comes with trying to plot the PSDs and seeing they're essentially identical; it's as if the 2nd stage has no effect at all. In this case, both have an SNR of around -100dB or so. I'm not sure what sort of modification is needed to have the MASH structure have any effect; I've tried messing with the feedback delays, adding scaling at the output (either x2 for the MSB or 0.5 for the LSB to give it some sort of a "2-bit" output that I'd want for a circuit implementation), and trying different combinations at the output (1 delay/2 differentiator, 1 of each, etc.)

I had an issue before of forgetting an extra differentiation/delay on the output of the stages which messed up the PSD, but that's fixed now. Is there something glaringly obviously wrong with this that I'm not seeing? I haven't found many useful papers or texts on digital 2-2 MASH DSM design.


texts: I'm trying to repair an 800W power supply (see my previous question on this.) One thing that gets me is that the design has two schottky diode packages (in TO-220) in parallel. I was always told this was A Bad Idea, but since they are thermally coupled to the same heatsink, does it present a problem in this instance? I've also noticed the same for the input bridge rectifier, two are used in parallel.


texts:
I followed this tutorial to build a li-ion battery charger circuit, I made two circuits (the last one better than the first), but any of them works as expected.

Schematics (I copied from the page above):

Board:

The circuit:

LED 1 (the one in middle) works as expected (glows if battery or
usb is connected)
LED 2 (the one above LED 1) flashes every time (not sure if should flash when battery is disconnected)
LED 3 never turns on (should glow if battery is full or if battery is absent)

Am I doing something wrong?


texts: So I have a 32 bit Float data type that represents a value of Ohms. I need to convert that signal to a 8 bit unsigned data type that represents mOhms, where 1mOhm per bit. Does anyone have any ideas how I can solve this? thanks everyone.


texts:
This might not even be the right place for me to ask, but I hope somebody can help;

I have an arduino mega with 4 PWM outputs (5v, fitted with 220 ohm resistor) that I would like to use to control about 2 meters of your average 5050 RGBW 24v LED strip. It should consume about 35 watts in all, so at about 370mA per channel it shouldn't be too monstrous to handle, I think.

All the LED drivers I have found so far require big MOSFETs with heatsinks, so I'm wondering how it is possible that all these cheap chinese wifi controllers can handle it in such a small and relatively low temperature package? Isn't it possible to make something like that? Suggestions i've had were using the IRL540NPBF 1 N which can do a whopping 140w on its own, which seems excessive to me.

Does anyone know of a component I could use on a typical 2.54mm board to make a nice little PWM controlled 4 channel LED driver?


texts: Real world brushed DC motor bulk capacitance calculations

texts:
There's a lot of great information on driving DC brushed motors from h-bridges. Preventing back-emf with diodes and bulk capacitance from electrolytic capacitors

When designing a high powered h bridge driver, people agree that bulk capacitance is required. It helps absorb the power surges when changes directions, braking, or back-emf. It also helps to avoid a voltage sag on the main rail.

It seems that people will throw as much large electrolytics in parallel as they can, hoping it is enough. To calculate how much is required, there isn't much information available. Other than saying the peak current, wire inductance, battery impedance, etc is required, then not showing what to do with that.

Is there any practical way to determine the amount of bulk capacitance required? My application is a super compact, 45A+ 4s H-Bridge driver. I can't afford the space to just blindly throw capacitors on and hope for the best.

I know there's not a great exact way to calculate this, but there has to be some way to get close.


texts: Is there a reason for potentiometers to be the moving part on a rotation sensor (joystick)?

texts:
I recently dug up an old joystick (Trust Predator) to see if my old flight simulator install would still work.

The joystick however didn't work at all satisfactory (erratic behaviour and drifting) so I took it apart to see if there were any bad connections. And there were... a lot. The reason is that all rotation sensors (which are just simple potentiometers) are located, I thought rather oddly: the 'base' was the part that moved, while the 'knobs' were fixed. As a consequence, the connecting cables move on every joystick movement, and without exception all of them were in a bad shape (especially the solder connections, but also broken insulation etc).

Why would the sensors be placed this way? Is it just bad design (Trust is a budget brand, after all), or is there a good reason why potentiometers used as rotation sensors are positioned this way? Is this design common in other applications?


texts: Identifying a power transistor (>24 V, >0.75 A)

texts:
I need help identifying this power transistor. From what I understand, they must be either NPN bipolar or N-channel FET/IGBTs, because the device is a low side LED-driver with common anode. The maximum voltage is 24V and the transistors probably are capable to switch bigger voltages.

The whole device can switch 75W at24V and there are 4 of these semiconductors, hence each of them should be able to drive 0.75 A at least.

 Sorry for the poor image quality, was done with my old samsung G SII through a scale magnifier.

gate/base is probably the lower left pin. The via leads over a 330 Ohms resistor to the Y of an AND-gate (ACT108) on the other side of the PCB.

I wasn't even able to locate the manufacturer (ViC ????) let alone the device itself (I266DN AE 13) in da intarrnet.

edit
I forgot to mention, why I want to know the model of this part, and if possible, the name of the manufacturer. I want to know the reliability of the whole device. There are some electrolyte capacitors which could limit the lifetime, but they aren't in a thermal stressed section and are well oversized. The manufacturer says it has only 20000 hours lifetime, and I was thinking that these possibly crappy transistors could contribute to the short lifetime.


texts: How do I change the output volume of this audio amplifier circuit?

texts:
In the circuit below, where would I place an audio taper potentiometer to modulate the output volume level?  Which of the resistors should get replaced with the pot and why?

If understand correctly, I should place the pot between the input decoupling capacitor and the buffer amp is this correct? Additionally, this circuit was designed for +-12V, if I am only capable of providing half of the +-12V, around +-6.2V, what effects will I observe, will the amp still function, just at a lower output?


texts: What is a good way to learn the Parallax Propeller chip?

texts:
I am experimenting with the Parallax Propeller chip but don't have any ideas for projects to learn with.

What are some good strategies on how to learn this chip? Are there any techniques or projects I should try?


texts: How to use 220v relay switch to stat/stop a 110v motor?

texts: How do I use a 220v well pump pressure switch to start/stop a small 110v motor using a relay switch? When the pump comes on the motor should as well.


texts: Reverse polarity protection with MOSFET: low voltage drop, 1-50V supply

texts:
I have a circuit that tests DC PSUs. They are typically unregulated and unsmoothed, up to 50V. It performs tests to establish I/V curves, down to about 1V, and up to about 3A. I want a sub-circuit that protects the testing circuit from accidental reverse-polarity connection of the PSU under test, without dropping too much voltage. (i.e., a rectifier is definitely not ideal).

The testing circuit has +5V, -12V and +12V supplies which can be used for the protection sub-circuit.

What circuit would achieve this? Ideally I would use an N-channel MOSFET given its particularly low On-Rds. This question comes close to the answer, but it will not work for a PSU voltage of less than about 5-10V, or more than about 20V. (Although a potential divider is suggested for use for PSUs above 20V). I have tried scribbling some circuits but am not getting anywhere. Is what I'm asking even possible?


texts:
I need that an Arduino NANO clone work with 3.3V.

Can an AMS1117-5V give 3.3V if supplied with only 3.3V?

edit: current consumption is 400mA max. the AMS1117 output current is 800mA.


texts: How can you cheaply make an output pin source/sink about 5 amps of 5vDC, 12vDC, 24vDC, and 120vAC selectively?

texts:
I'm working on a project and need to make I/O pins that are configurable to offer around 4 Amps or more of each voltage: 5vDC, 12vDC, 24vDC, and 120vAC.  The pins need to be able to source and sink each voltage, as well as control dc stepper motors with pwm (expected on 24v only).

My initial thought was simple, load switches for each positive/hot, and negative/neutral pin.  But I need about 30 of these little i/o pins and the cheapest prices I could find were about $90 just for all the switches!  There has to be a more intelligent design that doesn't cost as much.  I've been looking at variable regulators, high power opamps (analog voltage would be nice!), triode mosfets, analog frontend devices, tons of stuff I'm getting a little overwhelmed by.  I feel like I need help from someone who has a formal education.  My month long headache might be a 5 minute no-brainer for someone.

As for the inputs (other than power return) I feel like I have that handled.  I plan on using an fpga to configure each pin. This is intended to control tons of different motors, solenoids, keypads, sensors, and light bulbs all configured their own way.  A universal board beats making hundreds of adapter boards.


texts: Supply Voltage of the Instrumentation Amplifier INA332 from TI

texts:
At page 2 on top left there is written "Supply Voltage, V+ to V- ......... 7,5 V"

Low-Power, Single-Supply, CMOS INSTRUMENTATION AMPLIFIERS

Is that the supply range? Or is it meant like maximum V+ = 7,5 V and V- = 7,5 V (range would be 15 V)?

I can't figure it out with the data sheet. Will be grateful for any help!

Greets,
keep


texts:
On wikipedia

  In analog systems, full scale may be defined by the maximum voltage available, or the maximum deflection (full scale deflection or FSD) or indication of an analog instrument such as a moving coil meter or galvanometer.

So, is FSD is the same as FS?


texts: Using SPICE to model dV/dt filter for inverter motor drives

texts:
I am starting to learn LTSPICE to create model where I can test various passive filter topologies for inverter drives where the output PWM has very short rise times and high switching frequency.

I have managed to create a model which accurately models the voltage reflection using a PULSE source and a lossless line model.

NETLIST as follows:

V1 N001 0 PULSE(0 20 0.1u 0.1u 0.01n 0.3u 1ms) Rser=50
T1 N001 0 N002 0 Td=0.25US Z0=50
T2 N002 0 N003 0 Td=0.25US Z0=50
R1 N003 0 100
.tran 0 1.8us 0 0.1n
.backanno
.end

Figure:

Result:

Green: Voltage pulse from source
Blue: Measurement between lossless lines
Red: Measurement at cable end (motor terminals)

It is seen that the pulse has a travel time from the source to the motor, and that the motor terminal voltage is higher than the source voltage due to the voltage reflection and impedance mismatch (50 vs 100 ohm).
The second pulse in the x-axis is the pulse returning to the source.

Now, the problem:

When I add filter components, the voltage essentially drops to zero after the filter.
This is what I have implemented:

I expected that this would damp the overvoltage.
The values are extracted from an IEEE paper (A. von Juanne, "Design considerations for an inverter output filter to mitigate the effects of long motor leads in ASD applications")

The resulting voltage measurements look like this:

where the green trend still is the source voltage pulse.

The voltage is much lower at the receiving end that what I expected and I hope that someone with better experience than me have some tips to create a model for this scenario.

UPDATE

I got it to work as expected after being more careful with the parameters and components.

The updated netlist:

V1 N001 0 PULSE(0 648 10u 0.025u 0.01n 1.2u 5us 0) Rser=0
R1 N003 0 1MEG
L1 N001 N002 0.2m
R2 N002 N004 190
C1 N004 0 0.075µ
O1 N002 0 N003 0 PL1
.tran 0 501u 0 1n
.model PL1 LTRA(len=30 R=6m L=0.36u C=0.01n)
.backanno
.end

Updated schematic:

Updated result:

From LTSPICE

From original IEEE paper

After exporting the data values and letting LaTeX present the same result

(PS: Dont mind the blue dashed line and 20 % tick, that was just testing)


texts: How many nrf24l01+ can be transfer data between themself in one pipe

texts:
My IOT project has ten or more nrf24l01+ modules which They're going to get orders from one nrf24l01+ module and then get back response to that one nrf24l01+.
Can i do it in one pipe?


texts: how to treat a diode in a transient analysis

texts:
Hi, this fig is a model of a circuit, where the cap is representing the gate-to-source capacitance of a hi-side FET in a bridge circuit driving a coil. VD is the intrinsic diode in the FET from Source-to-Drain. The Drain is tied to 3.3V (vcc), the pulse driving the gate goes up to 12V (vdd is a 12V step).

I'm only modeling (only interested in) the instant when the gate of the FET is driven by the square pulse, prior to the FET turning on, and am interested in obtaining the transient current that will flow through the diode from vdd to vcc. I can't figure out how to compute the current through the diode during this time. Effectively, the full 12V from the pulse (vdd in my model) is applied to the anode of the diode, connecting vcc to vdd through the diode. I'm interested in calculating what this current will be, but don't know how to use the diode equation in this case (Vd is no =~0.7V, it's 8.7V). How do I treat the diode as an ohmic element? What parameters from the diode datasheet would I use to determine what it is/would be?

Thank you,
Jorge


texts: Can someone please clarify something to me about large electric motor protection

texts:
I am currently learning about large electric motor protection systems.
In a "stator faults" section there is an opening statement that has confused me.
"DC overcurrent tripping devices on the breaker take care of ground faults or line faults. These devices are thermal or dashpot types giving an inverse time current characteristic, and usually provide instantaneous trip at high current."
What does the above statement refer to? AC or DC motors?
Thank you.


texts: Why do external batteries (a.k.a power banks) have power buttons?

texts:
At first thought, it's a good idea to prevent any short circuiting via contact with external hazards such as water or coins, but how often do that happen?

If the battery is already in contact with water, then it's going to get fried anyways. And it can't be so often that metal is in direct contact of the ports (on the battery) to warrant a dedicated power button.

Are there other reasons for including a power button on external batteries that I may be missing? Is it OK for them to not have power buttons?


texts: Does a diode block current but not voltage?

texts:
When running this test circuit on CircuitLab and my expected result was that only M1 would open
but then i noticed that the M4 mosfet is also open even though there is a diode between it and the the 3V
the Gate threshold on both is set to 1.5v

i also noticed some strange spikes appearing on the current

Does it mean a diode blocks current but not voltage ?

simulate this circuit – Schematic created using CircuitLab


texts: Driving a MOSFET with Negative Off- State Gate Voltage

texts:
I know in practice Mosfet switches are driven by 0V to any Positive gate voltage (e.g. 0V - 15V). I am using a Mosfet pair (PMOS and NMOS) to switch 10A currents in pulses and the datasheet of MOSFET states that both PMOS and NMOS can be driven by max +20V/ -20V gate voltage.

What effects will using negative voltage to switch off a mosfet have on the performance of my circuit? Other than increased turn-on time of mosfet switches (as I need more charge to switch ON mosfet loaded with negative charge)?


texts: Simple differential amplifier with active load for ADC comparator

texts:
I'm wondering, why can't a simple differential amplifier with active load followed by 2 inverters (to boost to VDD and GND logic level signals) be used as a comparator in SAR ADCs? Like this

What's the need for latching and all this positive feedback stuff if the sampled input of the ADC remains at the input to the diff amp for a while, why use positive feedback?


texts: Would you help me understand this simple circuit?

texts:
I have three questions:

Is it common emitter or  common collector (emitter follower) or something else? How do you recognize it?
What is the function/usage of R1 and C1? Are they for biasing the transistor?
The most important question is: What is the function of C3?

I asked the third question because if it is common emitter, we can take the output from the collector Vc and there is no need for C3. If it is a common collector (emitter follower) we can take the output from the emitter Ve and also there is no need for C3. I don't know why collector voltage and emitter voltage are connected by C3?


texts: Is the self-powered USB hub powering my devices?

texts:
I bought a cheap Hub for powering my 5 arduino(s). It has an AC wall power adapter. Can i determine if it actually powers my USB devices and what amount of current per USB port can deliver?

The USB hub has one LED, that lights when i power it with the AC adapter, and until now everything works ok.

In the control Panel, in the USB ports i can't find any useful information. I can see the Hub as port 4 hub 3, but says power required "unknown".


texts:
I can not find a true pass-through KVM Switch for USB-C (Thunderbolt) to buy. So I am thinking about maybe building one myself. Currently I am just  plugging and unplugging the Thunderbolt (USB-C) cable from my docking station to the laptop I want to use at the moment.

Why is there no Thunderbolt KVM Switch that does exactly that? Is this technically not feasible or what is the reason none seem to be offered by the industry?

Some active USB-C KVM Switches are offered. What I understand is they do not offer full Thunderbolt bandwidth and they are also rather expensive at ~$150-250.

I am thinking about just buying three Thunderbolt cables and having them switched with a mechanical switch. I mean, it works if I just unplug one laptop and plug the other in. Why isn't it available already in a box I could buy? Is there a technical barrier for that? What mechanical device should/could I use for such switch (the actual switching) if I were to build one myself?

Ideally the switch will keep the power delivered (maybe from a second external USB-C power adapter, I have them available) and just emulating plugging/unpluging the cord for the data lines.

So the questions are:

1) is this is feasible at all?

2) what could I use to mechanically switch the Thunderbolt signal cables?


texts: Is it 'ok' to use a switched power supply to power a processor core?

texts:
I'm currently working on a project which features an Analog Devices Blackfin DSP Digikey link. This DSP requires 1.3V to power the core. I plan on having my project be battery powered, thus I'm looking for efficient power regulators.

I've noticed in a lot of schematics that use this chip (and other DSPs in general), the core voltage is typically regulated via an LDO. I understand that LDO regulated power will be cleaner then a switched power supply, but an LDO would be less efficient given that I will be stepping down from 3.3V.

I wasn't able to find anything in the Blackfin datasheet regarding maximum core voltage ripple. So my question: is it 'ok' to use a switched power supply to power a processor core?


texts: Assuming I am considering A single stage class A amplifier, as we know the efficiency of the amplifier is AC power out/quiescent Dc power in, but the problem is when signal is applied shouldn't the formula be ac power out/instantaneous dc power out at that time? Because when the signal is applied the input dc power should be more than the dc quiescent power, so the actual (instantenious)dc input power at that time should be more and that's the original input power, not the quiescent input power should be considered as input power. Isn't it correct?


texts: Toggle between two usb cords with a 2 pole 2 throw switch

texts:
I'm looking to toggle between two USB cords via a 2pdt switch. I'm not sure if this is possible but I'll elaborate.

I am building a game controller out of an XBOX One PCB using the crossbone (pictured here) PCB. This PCB can operate off a wired connection or a wireless connection. I've determined (as best as an idiot like me can) that the best way to power the PCB is via a USB power bank (similar to this one) wired to the 'USB out' as pictured next to the micro 'USB in' on the crossbone.

I'd like to wire this in a way that my USB cord can switch between powering the PCB directly or powering the power bank which will charge via USB and in turn power the USB. This will allow me to power the USB via the power bank and run wirelessly and enable me to plug the USB in before my switch to recharge the power bank. I realise I can achieve this with a 4 pole 2 throw switch however I simply don't like the style of the switches I have found and have my little heart set on a simple 2pdt rocker switch.

So here's where I have a few questions. When the power bank is being recharged via USB I'm assuming it needs to have data + and - hooked up in order to regulate or cut power once the power bank is fully charged; is this true? Is there a way I can achieve switching between these two USB supplies using a 2pdt switch? I'm assuming my circuit is going need to include something along the lines of a relay but frankly I'm in over my head here.

Any advice would be appreciated.
Thank you in advance.


texts:
I'm working on an arduino project and I need to drive a motor that is rated at 120V and 0.5A with No Load. Since this is a fun project and I'm trying to reuse some parts, hence the 120V dc motor I'm trying to reuse which came from an old coffee grinder.

The input is 120VAC and I'm using a full bridge rectifier but that yields ~169V at the output because of the RMS voltage output.

1)How do I step down the voltage from 169V?

2)Can I use an inductor in series with the capacitor to lower then voltage? If so what formula do I use to calculate the proper size inductor?

3)I noticed in the circuit of the old coffee grinder that it has a power line choke before the rectifier. What purpose does that serve?

My knowledge of circuits is rusty so thanks for the help in advance.


texts: 12VDC Worm Gear motor suddenly stopped working now no current goes through it

texts:
I have 12VDC worm gear motor that i was setting up for a project. I have it connected to a store bought H-Bridge module and that is hooked up to a 12VDC power supply. I was working coding up a GUI for the setup and was testing out a slider widget. I have it so that the max value of the slider was 100% duty for the PWM modulation.
So I am messing with the controls, starting stopping and everything seems fine. All these test were conducted at no load. I made another change in my SW and suddenly it does not work. The change to the SW consisted of adding a stop button that overrides the slider value and sets the duty cycle to zero. Adding a manual stop that should cause the motor to cease functioning.
Troubleshooting
Test HBridge: I bought two of the same motor and attached it breifly and the shaft spins (so circuit is functional)
Test Motor: I disconnected the motor from the setup entirely (not touching h bridge or SW) and wired directly to the PSU. The motor will not spin and it will not draw any current.(motor appears to be borked)
Test PSU: I had a duplicate motor and it spins (PSU is fine)
I was trying to save a few dollars going with the cheap imports but I did not expect failures right out the box.
Any one know what is going here
My components
Motor
H Bridge
Power Supply
Power supply used to test
I am confused on what failed and how to avoid going forward.


texts: Eagle: Selecting a group by signal name?

texts:
In the eagle board layout, I want to group a specific signal specified by its name so I can move it to another layer via the CHANGE LAYER command.

I do not manually want to click on every segment of the signal, after all, there is no point in naming something if you can not refer to it by its name.

So far, I have figured out that SHOW $signalname will highlight my signal, but I will not be able to apply a CHANGE command to the highlighted signal.

On the other hand, GROUP will select a GROUP on which CHANGE commands will work, but seems only suitable for selecting parts with the mouse, via a rectangle or one segment per click.

Is it possible to accomplish my goal without either delving into ULP or manually hacking the *.brd xml?


texts:
I'd like to determine how fast I can read sensor values on a bus given the bus rate/bandwidth. According to the device documentation found here, assuming a 7-bit address there are 49 bits involved in sending & reading a single sensor temperature value. A picture is also shown here.

Would the transfer rate simply be 49 bits / 100kbps = 0.00049 seconds / read?


texts: How can I control the output level from a HV (220VDC) floating regulator using a DAC?

texts:
I have a 240V DC supply I want to clean up and make adjustable (150-220V) with an LR8 high voltage floating regulator.
I can't use the standard way of connecting the DAC to the adjust pin (current summing junction) of the the LR8 with a series resistor as the voltage is too high - the adjust pin is only 1.2V under the 220V output voltage means a DAC will not have a long life.
Could I use a MOSFET with a gate driven by a DAC to its linear region as below to set the voltage?
Thanks!
EDIT: All of the resistor values are approximate and should be taken with a handful of salt.
https://i.imgur.com/SDAlTDf.png


texts: can i cut a large strip board into a smaller one?

texts: I need a 17 hole by 8 hole strip board. I could only buy a much larger one. Can I cut the larger one to the size I need without destroying it? If so, how would I do that?


texts: Atmega32 can't verify after setting correct fuses for external crystal. HELP

texts:
I am having trouble with some Atmega32A's purchased off from eBay. The MCU's does not seem to be fake as they are functioning properly. I am experiencig the following problem: I want to use external crystal of 14.7456MHz. With default fuse settings (

0xE1 / 0b11100001 low fuse;
0x99 / 0b10011001 high fuse;

) I am able to program the MCU and it verifies, everything is OK when it works with internal clock speed at 1MHz. When I change high fuse to 0b11001001 to disable JTAG and program CKOPT, it works again. But when I change low fuse to make the MCU to use external clock, it writes the hex, but cannot verify the MCU, and it's not working. Here's the output:

> "make.exe" program
avrdude -p atmega32 -P usb -c usbasp    -U flash:w:main.hex

avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e9502
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: reading input file "main.hex"
avrdude: input file main.hex auto detected as Intel Hex
avrdude: writing flash (15896 bytes):

Writing | ################################################## | 100% 6.73s

avrdude: 15896 bytes of flash written
avrdude: verifying flash memory against main.hex:
avrdude: load data flash data from input file main.hex:
avrdude: input file main.hex auto detected as Intel Hex
avrdude: input file main.hex contains 15896 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 4.87s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0x0c != 0x00
avrdude: verification error; content mismatch

avrdude done.  Thank you.

make.exe: *** [program] Error 1

> Process Exit Code: 2
> Time Taken: 00:12

The programmer is working fine, I can confirm the circuit is working because it's working with Atmega32 when setting to use external clock (I am using 2x22pF ceramic capacitors right next to the crystal). The issue is with these Atmega32A's. What can be the reason? I found this, but I think 1111 is the correct one for the crystal.

Device clocking options             CKSEL 3..0
External crystal/ceramic resonator  1111-1010
External low frequency crystal      1001
External RC oscillator              1000-0101
Calibrated Internal RC oscillator   0100-0001
External clock                      0000

Thanks in advance.


texts:
I need help with this DC circuit problem:
When the switch is open, voltage between points A and B is 2V. When the switch is closed, through variable resistor \$R_{p}\$ flows maximum current, and \$R_{p}\$ has the maximum power. Calculate value of resistor \$R_{2}\$.

Given parameters:

\$R_{1} = 100\Omega\$
\$R_{3} = 200\Omega\$
\$R_{4} = 400\Omega\$
\$U_{ab} = 2V\$ (open switch)
\$I_{pmax} = 10mA\$ (closed switch)

What method to use?


texts: Total current current equation in P-N junction

texts:
So Okay I get why there is a negative sign in the equation for diffusion current of holes since the gradience is actually negative if we put our coordinate axis in the bottom left corner for example in the 2nd picture where x points right side..
But that then makes Jp overall positive, There is no negative term in the equation, How is that possible if you actually know that in a no bias situation the total current is equal to zero?

The same applies to Jn. The only possible way I could understand this is by substituting E with a negative sign since it points to the left in the 2nd picture.

Any clarifications ?


texts:
I'd like to make a beacon system for robots where the beacon will have some IR LEDs around it pulsing at some known frequency. The module that hooks up to the robot will have a few IR photostransistors (are photodiodes better?) to detect direction. I'm thinking I'll have an MSP430 as the brains for each and speak I2C or TTL to indicate direction on the robot side. How do I detect that specific frequency so I don't mistake sunlight, etc. as the signal? How sensitive would this be? Do I need really powerful LEDs? What are all the considerations?

I want something like a 1 way version of this pololu beacon except one way (although two way might be a good idea too).


texts: Sharing lots of signals between micro-controllers

texts:
I have a board where a backup MCU is connected to all the same IOs as the main board. An error checking mechanism will select which MCU to power up. The other one will have all of it's IO ports in Hi-Z state to avoid shorts or other such problems.
Because of this requirement, ~90 signals are shared between the two MCUs, making routing quite complicated. The board must not be larger than 3.5" by 3.5" with a max height of .5" and space is lacking, even using vias and such. I'm trying to find the best way out.
The ideas I've come up with are:

Use a 4 layers PCB. Since we are a students team, the ~60$ increase is significant and we'd like to avoid it if possible. That said, I'd be ok with hearing this is the best course of action.
Use ribbon cables to link the various pins together. Pros: cheap, Cons: mechanically flimsy and more susceptible to electromagnetic interference.
Solder the two MCU on top of each other. Pros: Less space taken and less soldering, Cons: Really not sturdy. Not an option unless there is a way to make this more solid.
Add a PCB on top of the first using sockets/headers. Pros: Simple, sturdy. Cons: This adds a cost for the second PCB, and at that point I'm not sure this is more interesting than the 4-layers PCB. This also means the stacked board will need to be super close to the primary. While the MCUs should not make more than 1W each, the restricted air-flow could be bad for thermals (?).

The signals are not high-speed  and/or high power, so the impedance and capacitance of the various options are not important.
What should I choose? Do you have other ideas? Am I missing some trade offs?


texts: Why does an XLR connector use 3 pins instead of two

texts:
Why does XLR connectors use 3 pins instead of just 2. The wiring is

Pin Function
--------------------------------
1   Chassis ground(cable shield)
2   hot
3   cold

(http://en.wikipedia.org/wiki/XLR_connector#Three_pin_-_audio)

Why do they use an extra pin instead of the connector shell to connect the cable shield?


texts: Board to Wire Connector Type used between Small Display and Main PCB

texts:
I'm in the process of designing a PCB/Prototype and looking at different types of board-to-wire type connectors. In particular, I want to connect an SPI OLED display to the main PCB. It needs to be removable and small, but not too small that it's delicate/fragile. It also needs to be a low-profile connector since the display and PCB are packaged closed to each other.

Here's the underside of the housing. The main PCB will be within the housing just beneath the display:

Is there another name or trade-name for these type of parts that I should be searching for?

Should I look at standard .1" header pitch for connectors or is there a smaller, yet still common pitch that is still robust and inexpensive?

Also, is this the correct way to connect the  display to the pcb for this application?

update: I looking for low profile type connector like this(not not as small and with 7 connectors:


texts:
I have a failed power mosfet on my board which is PSMN3R0-30

https://assets.nexperia.com/documents/data-sheet/PSMN3R0-30YL.pdf

It has low Rds (on) = 3 mΩ

It is common for these to fail in these laptops (poor design) and would like to know if I can replace it with a more suitable mosfet. I have been looking at many datasheets for other mosfets (30v, 100A) but I just can't figure out what one would work in its place. Maybe these?

https://docs-emea.rs-online.com/webdocs/1579/0900766b815790d7.pdf

https://docs-emea.rs-online.com/webdocs/1560/0900766b81560cf4.pdf

I can buy the PSMN3R0-30 but not from the UK so shipping is expensive.

Thank you


texts: Understanding PIC32 watchdog timer operation

texts:
I'm new to uC development and have been fooling around with the PIC series for about 6 months now. I recently started working with the PIC32 and Microchip's XC32 C++ compiler. I don't know if I have a fundamental misunderstanding of how the WDT works on the PIC series, or if there is some caveat of which I am unaware, however I have some code that I think should light an LED on RA0, then turn it off and after 512ms the WDT should reset the uC and the process should start over. What is actually happening is that the LED comes on momentarily, then goes off and never turns back on. I don't know if this means the WDT is incorrectly configured or what. Here is my code:

#include <xc.h>

#define LED _LATA0

/*
 *
 */
int main(int argc, char** argv) {

    WDTCONbits.WDTPS = 0b1001; //512ms postscaler
    WDTCONbits.WDTCLR = 1; // feed the watchdog

    WDTCONbits.ON = 1; // enable the watchdog

    TRISAbits.TRISA0 = 0; //output on RA0
    ANSELAbits.ANSA0 = 0; // digital only

    LED = 1; //led on
    int i = 100000;
    while(i--);
    LED = 0; // led off
    while(1); // hang up and let WDT reset us

    return 0;
}

What part of successfully using the WDT am I missing?


texts: Circuit Breaker Simulation in Matlab with Mayr and Cassie Equations

texts:
I'm trying to understand how to model arc circuit breaker.

There is a simulation example as called Mayr and Cassie Circuit in Matlab&Simulink.

I have examined Mayr and Cassie Differential Equations to understand parameter determination in this circuit.

I simulated to see how to effect by changing input and output parameter R,L and C values. I see that only amplitude of current and voltage changed.

What parameters should I arrange to change arc time and arc voltage?

Example can be found in the following link:

https://www.mathworks.com/help/physmod/sps/examples/cassie-and-mayr-arc-models-for-a-circuit-breaker.html


texts: Polarity of feedback in a feedback circuit

texts:
How should I check whether the given configuration has a negative or positive feedback. I am stuck because, I know that as Vin increases the drain current will increase but after that I don't know how to proceed.

So please explain how should I proceed with this?


texts: Is BJT amplifier a viable option if the design needs to be replicated without calibration?

texts:
||Sorry for messing this up the first time. This is my first post ever in a technical forum. Need to pick up the ways of the crowd. Thanks for all the feedback and help. Well appreciated||

I intend to design a product targeting the rural market. As each penny counts for my customers, I need to optimize both the design and manufacturing process to be as cost effective as possible. The design involves a boost converter which should look something like this except for the following.

a. Input will be a 12V battery

b. The controller will be UC3843/5, a variant of that used in the schematic

c. The load will be a series LED string (open circuit or constant current 150mA with 20V/40V/60V).

I am experimenting all the options and one of them involves replacing the controller IC with a 555 timer PWM generator. In such a design, I need to amplify the voltage across a current sense resistor like R10 with a gain of about 30. I could either use an op-amp configuration or a BJT amplifier to do this. BJT looks cheap and may reduce my BOM cost. But to my knowledge, if the gain of a BJT transistor varies from piece to piece then I need to add a calibration process which increases my manufacturing cost.

So is there anyway I could use a BJT amplifier circuit in a design that can be replicated without needing to calibrate it each time.


texts: center tap transformer full wave rectifier current rating

texts:
for a 24V output, I have the option to purchase a 0-24V 5A transformer, or a 24-0-24V 5A transformer. Can I draw 24V 7A from the 24-0-24V transformer (full wave rectification with 2 diodes)? Assuming I^2*R heating loss, since each winding is being used half the time, I should be able to increase the current sqrt(2) times, right? Any other possible problems (core saturation, core heating etc) that I should be worried about? Will the 24-0-24 transformer provide a bigger safety margin if I'm only drawing 5A continuously?

edit: sorry for the stupid question. Neil_UK is right. To answer my own question, I may be able to draw 7A, but the voltage will drop, as it is defined by the secondary winding resistance (and the primary side voltage and turns ratio). 48V 5A is not the same as two 24V 5A transformers. I'm probably better off getting a single 24V 7A (or 8 or 10A) transformer. Less headache, more stable voltage and more safety margin at not too much higher cost (considering transformers live for decades).

PS: also, this is for a bench power supply, so SMPS will not do (without DC-DC tracking pre-regulators and stuff). In hindsight, I think I will need 12V and maybe 6V taps.


texts: Rule of Thumb for PCB pad sizes of SMD devices?

texts:
I am trying to make a PCB for the first time and am concerned about the sizes of the soldering pads over the actual dimensions that I should realize on the board. That is, with the following diagram:

What size should the top pin's pad be? The dimensions for this pin are given as 3.00 x 1.75 mm. About what size should the associated soldering pad be and what (if any) is the general rule?


texts: How to avoid UART chip power consumption

texts:
I am using ESP32 DevKit Wroom - which is on NodeMCU. I am running this on a battery power. and if I attache USB or 9 volt supply (battery) on the VIn (i.e. 5V), the board consumes aprox ~20 mA even in deep sleep mode.
If I supply voltage 3.5 (Through the liIron battery) on pin 3.3, it will certainly bypass the voltage regulator.
Other than this Voltage Regulator, there is UART chip which is equally power hungry.
My question here is, IF i supply 3.3 Volt using on-boarded pin, will it stop current going to UART? Do we have devkit PCB diagram that can explain this?
Also with all this, will my NodeMCU with ESP32 really run on few UAmp as described in ESP32 datasheet?


texts: Is input leakage current a valid way to calculate the input resistance of a digital input on a microcontroller?

texts:
I'm trying to calculate the value of a resistor to protect a digital input on a microcontroller (10Ω and 1kΩ in the image below):

The microcontroller datasheet (PIC16F1718 Datasheet) doesn't specify an input resistance (shown as 20 MΩ in the drawing,) so I'm unable to determine how high a resistor value I can use without interfering with logic levels.
The datasheet does list the max "Input leakage current." I understand that to be the current into the input pin when the input voltage is at maximum. Is that correct?
Since I know the input leakage current and the max input voltage, can I use Ohm's law to then calculate the DC resistance of the input pin? When I do the calculation I get 5MΩ which seems reasonable.
Source for circuit diagram


texts: Why can't I program a ZC706 (Zynq) board a second time over JTAG?

texts:
I have a ZC706 board equipped with a Zynq 045 FPGA. I switched the jumpers to add the Zynq into the JTAG chain of th Digilent programmer. The first programming works as expected, but the second programming does not alter the FPGA configuration.

When I run a full power cycle on the complete board, I can program the FPGA again, but no third time ...

Why can't I program a ZC706 board a second time over JTAG? Does the ARM lock the internal configuration FSM?

The "Done" LED stays always high so iMPACT doesn't notice a programming failure!

My task is to port a design from KC705 onto the ZC706. The hardware test example needs no ARM - this will be implemented by others :).


texts:
I am trying to understand the physical significance of \$\alpha
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegaaa!3796!
\$ and \$D
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraaaa!36C0!
\$ in the following equation:

\$y\left( n \right) = x\left( n \right) + \alpha y\left( {n - D} \right)
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEamaabm
% aabaGaamOBaaGaayjkaiaawMcaaiabg2da9iaadIhadaqadaqaaiaa
% d6gaaiaawIcacaGLPaaacqGHRaWkcqaHXoqycaWG5bWaaeWaaeaaca
% WGUbGaeyOeI0IaamiraaGaayjkaiaawMcaaaaa!45A1!
\$

where \$x\left( n \right)
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEamaabm
% aabaGaamOBaaGaayjkaiaawMcaaaaa!3970!
\$ is the input audio,\$y\left( n \right)
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyEamaabm
% aabaGaamOBaaGaayjkaiaawMcaaaaa!3971!
\$ is the output (echoed) audio, D is the echo delay (in samples), and \$\alpha
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegaaa!3796!
\$ governs the amount of echo fed back.

I have simulated above equation in MATLAB, recorded 2 sec. of audio data, quantized it and passed it to above equation and played back output signal. They clearly 'differ' to each other but I don't how to describe it. Can anyone assist on this please?


texts: Microcontroller with integrated GSM & GPS support?

texts:
I am looking for a single chip microcontroller with GSM & GPS solution. Is there any microcontroller chip which is specifically available for GSM & GPS solution? So that it will act like single chip with GPS, GSM (without analog design for GSM) and with programmable controller.

Looking forward for your valuable suggestion. If not, what are the other options I should consider?

Excuse me if isn't a valid post.


texts:
To provide an adjustable, switchable reference voltage to the xVREF input (Iref -3uA to 3uA) of the current control of a DRV8825 stepper motor driver allowing to reduce power during stand still, I tried the following circuit:

As expected, I can for example switch between 1V and 260mV allowing to reduce motor current from 1A to about a quarter, still being able to adjust the current.

I'm just unsure if this is a good design?


texts: Multiple Terminating Resistors on RS-485 Bus

texts:
I bought this TTL to RS-85 board and before connecting it to my Arduino I decided to double check (reverse-engineer) its circuit and I can see there's a 120 ohm resistor between the A and B outputs.

I know we are only supposed to terminate the end of the RS-485 bus, but this is a pretty popular board and it appears to terminate every single node of the bus if I use it.

How much of a problem can this be? Should I bother to remove the resistors? I guess it would load the signal more and more as I add more nodes, so when will this be an issue? Can this pull too much current from the MAX485 and fry it?

In case anyone is wondering, this is the resistor:


texts:
simulate this circuit – Schematic created using CircuitLab

I am taking a -8 volt signal and using a resistor divider to make it -3 volts by using a 16.5k ohm resistor as r1 and 10k as r2. I am feeding the -3v into a single supply opamp (+5 and gnd) in the inverting configuration with unity gain (using two 10k resistors) in order to obtain 3 volts. Will the resistor divider before the unity gain non-inverting opamp effect my unity gain?

Essentially i am taking a signal that goes from -8 to 0 and i want to turn this into 3v to 0 for input into a ADC.


texts: What kind of amplifier do I need to drive a piezo multi layer ceramic speaker

texts:
First post here, hope someone can guide me.

I would like to use this speaker:

http://www.dbunlimitedco.com/product-detail/SZ300812-1

on my Raspberry Pi. I have an PAM8403 amplifier board driving a regular speaker and it all works well. The board is like this one:

http://www.ebay.com/itm/3pcs-PAM8403-2X3W-Mini-Audio-Class-D-amplifier-board-2-5-5V-input-/181888663216

Do you think this board can drive the ceramic speaker from 1st link?
If not, any suggestions?


texts: WiFiClient fails to connect to ESP8266 access point

texts:
I am trying to connect between two ESP8266-01 chips using one as an access point and another in the station mode connecting to the AP. I am using a simple WiFiClient (from the examples) to create a connection to an access point hosted by another ESP01. It fails to connect to it.

I have tried using my router WiFi as an access point and the ESP8266 client connects to it fine. It is able to request URLs and response from the same but when I just change the settings to an access point hosted by a ESP01, it fails with an error. Can you please help me identify why does it fail only for the ESP8266-01 access point?

Please note that I am able to connect to this access point ESP02 using my browser and request for a page. It works well with no issues but not with another ESP Client.

  #include <ESP8266WiFi.h>

  const char* ssid       = "ESP02";
  const char* password   = "pswdesp002";
  //const char* ssid     = "EAGLE_EXT";
  //const char* password = "xxxxxxxxxx";

  const char* host = "192.168.4.1";
  //const char* host = "192.168.1.1";
  const char* streamId   = "";
  const char* privateKey = "";

  void setup() {
    Serial.begin(115200);
    delay(10);
    monitorWiFi();
  }

  void monitorWiFi()
  {
    // We start by connecting to a WiFi network
    if(WiFi.status() != WL_CONNECTED){
      Serial.println();
      Serial.println();
      Serial.print("Connecting to ");
      Serial.println(ssid);

      WiFi.begin(ssid, password);

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

      Serial.println("");
      Serial.println("WiFi connected");
      Serial.println("IP address: ");
      Serial.println(WiFi.localIP());
    }
  }

  int value = 0;

  void loop() {
    delay(5000);
    ++value;

    monitorWiFi();
    Serial.print("connecting to ");
    Serial.println(host);

    // Use WiFiClient class to create TCP connections
    WiFiClient client;
    const int httpPort = 80;
    if (!client.connect(host, httpPort)) {
      Serial.println("connection failed");
      return;
    }

    // We now create a URI for the request
    String url = "/setlevel/";
    url += "&value=";
    url += "50";

    Serial.print("Requesting URL: ");
    Serial.println(url);

    // This will send the request to the server
    client.print(String("GET ") + url + " HTTP/1.1\r\n" +
                 "Host: " + host + "\r\n" +
                 "Connection: close\r\n\r\n");
    unsigned long timeout = millis();
    while (client.available() == 0) {
      if (millis() - timeout > 5000) {
        Serial.println(">>> Client Timeout !");
        client.stop();
        return;
      }
    }

    // Read all the lines of the reply from server and print them to Serial
    while(client.available()){
      String line = client.readStringUntil('\r');
      Serial.print(line);
    }

    Serial.println();
    Serial.println("closing connection");
  }

Debug messages:

Connecting to ESP02 .......
WiFi connected
IP address:
192.168.4.2
connecting to 192.168.4.1
:err -8
connection failed
connecting to 192.168.4.1
:err -8
connection failed
connecting to 192.168.4.1
:err -8
connection failed
connecting to 192.168.4.1
:err -8
connection failed
chg_B1:-40
connecting to 192.168.4.1
:err -8
connection failed
chg_B2:0
connecting to 192.168.4.1


texts: Help understanding transformer AUX winding

texts:
I'm new here and I'm looking for someone to help clarify the AUX winding of a transformer, more specifically in a switched psu.

I see schematics where it's being used either as feedback or voltage input to an ic on the primary taken from a winding on the primary (at least that's how it seems to me). Here lies my confusion.

My understanding is a magnetic field created in primary creates a flux in secondary that outputs different voltages dependent on winding/s. So how can there be a second winding on the primary side that induces voltage in the hot side used as an AUX? Am I missing something simple like are the windings really on the secondary but the pins are connected to primary/hot side?


texts: Switching a ULN darlington array from TLC5940 driver?

texts:
I feel this is going to be a stupid question-

TLC5940 is a 16-channel, constant-current sink LED driver.
ULN2004A is a high-voltage high-current Darlington transistor array.

Since the TLC5940 is sinking current, I take it you can't hook up the outputs to the inputs of the ULN2004A to drive something more demanding?


texts: (Beginner) Type of (NPN?) transistor to use for RasPi

texts:
I'm new to EE. I burned out a Raspberry Pi by running an electric motor directly from its GPIO pins, and then I learned about transistors. I now have another RasPi, but I'm not sure what transistors to buy. I plan on using the RasPi's 3.3v GPIO pins for the base and a 4 AA batteries connected for the collector. What NPN transistor should I buy (or what pack of general-use NPN transistors should I buy that I can adapt to fit) for this project? Are there any methods to determine which transistor values are required? If it's best to just get a pack of general-purpose transistors, what do I need to do to accomodate for the difference in voltage/amperage tolerance? Would any capacitors be required in the circuit to account for the motor's interference? If I wanted to replace the motor with an antenna, would I have to change anything?

Let me know if my phrasing is unclear. Thanks for any replies, I know that this kind of thing must be annoying to you.

Edit: The motor is an example. I just wanted to know what to use for that current.


texts: Determining Battery Charging and Discharging Rate Based on Max Current and Nominal Voltage

texts:
I am having difficulty in figuring out some basic stuff and confused with multiple equations.
I am working on a simulator which simulate a hybrid vehicle journey for some period of time. During journey the vehicle brakes and regenerate energy.
I have already calculated:

How much energy vehicle is regenerating at each braking event in kWh.
How long is each braking event in seconds (Time).

Battery specifications are:
Storage                = 30.6 kWh or 46 Ah

Max Peak Power         = 406 kW for 10 Sec

Voltage                = Nominal = 666 V , Min = 486 V , Max = 756 V

Battery Ratting        = 6C

Battery max Charge / max Discharge Rate per hour = 6C * 46 Ah = 276 A

Question:
All I want to know is that in one second time, how much energy I can send to battery and discharge from battery?
So in my algorithm I can automate the code to send only the amount of energy which battery can absorb for such given period of time and destroy rest in brake resistors.
I have tried this method but I am not sure if I am doing it correct.
please correct me if I am wrong.

Energy = V x I x T
Energy = 666(V) x 46(Ah) x 1 (hr) = 30636 Wh.

Now, Battery ratting is 6C. So,

Charge/Discharge current = 6 x 46 = 276 A.

Now, with 6C ratting:

Time to charge or Discharge (Run Time) = 46 (Ah) / 276 (A) = 0.17 hr
Run Time in Minutes = 0.17 x 60 = 10.20 Min
From this I can calculate 30636 Wh /10 min = 3063.6 Wh energy can be
charged and discharged from battery each minute. (for 10 minutes
period)
Considering this, 3063.6 wh / 60 sec = 51.06 wh energy can be charged
or discharged from battery at each second at 6C rating.
Again for Ws = 30636*3600 = 110289600 Ws /10 min = 11028960 Ws energy
can be charged and discharged from battery each minute. (for 10
minutes period)

Please correct me if I am wrong and guide me to perform these calculations properly.


texts: Variable Input Voltage Power Measurement

texts:
I've looked around the site for suggestions, but think this question is a unique one and would love some conversation.

I need a method to measure the average power in to a transducer.

This method must

Be able to measure the power of complex input waveforms (audio input, in this case)
Be able to measure the power of a signal oscillating around a DC voltage
Be able to measure the power of a signal oscillating around 0 V (AC)
Be able to measure the power of a signal which oscillates around some DC value, and not fail when the oscillation is of such a magnitude that portions of the signal fall below 0 V

The general parameters of the waveforms I'm measuring are

Audio, with and without DC bias
Chirps, with and without DC bias
Single frequencies, with and without DC bias

Before you ask, the DC bias is absolutely necessary! The physics of the devices for which I must determine the average power input require that I test signals with and without a bias.

In sum, I need a method of measurement which can accept voltage and current frequencies from 0-25kHz, is minimally invasive, is accurate to within a hundredth of a Watt (tenth might be okay too), and can handle voltages both with and without a DC bias that have peak to peak values from 0.1 V - 50 V.

An idea I've been given is that I could use transformers to remove the bias, measure the bias and the alternating component, and add them to obtain the average power.

Thanks in advance for any advice you can give!


texts: Party-line / Full-duplex intercom - mixing audio signals

texts:
Party-line or full-duplex intercoms allow for the simultaneous transmission and reception of audio from all connected stations, i.e. effectively there is an audio 'bus' and each station takes a feed from it and routes this to its headset, and also adds a signal from its microphone that is then available to the other stations.  The connecting wire can be either balanced or unbalanced.

simulate this circuit – Schematic created using CircuitLab

My question is: how do you add these signals together?  Do you simply connect the outputs of the output op amps at each station together onto the wire (via some form of AC coupling, perhaps?).

Is that what this guy does in this circuit here?: ComClone2 Circuit Diagram


texts: Upload to an Arduino from the command line

texts:
If I have a sketch compiled to hex, is it be possible to upload this sketch to an Arduino board using avrdude directly from command line?

Pekkaa figured out that arduino ide executes the following command when uploading the sketch:

./hardware/tools/avrdude -Chardware/tools/avrdude.conf -pm328p -cstk500v1 -P/dev/ttyUSB0 -b57600 -D -Uflash:w:/home/pekka/sketchbook/Blink2/applet/Blink2.hex


texts: Is the (PVC) sheath of a consumer grade USB cable waterproof?

texts:
We are building a marine instrument that will operate at up to 30m depth in sea water. Part of the design requires that the middle part of a USB type cable is exposed to seawater.

Most electronics cables that I know of are sheathed in black or grey PVC material, would this type of sheath be waterproof? Waterproof at 30m? Note that the cable should in not likely to be bio-fouled.


texts: Z80 - adding numbers in U2 - settings of register flags

texts:
We have Z80. This processor do following operation in U2:
200 - (-56).  What will be values of following register flags:
S - the oldest bit of result
V - overflow
C - carry
Z - result is zero.

Now, we know that in U2 we have: 200-(-56) = 200+56 = 00000000(U2)  Then, I know that:
S = 0
V = 1
Z = 1.
However, when it comes to C I am not sure about it. Although, we see the carried bit, I think that in U2 we can ignore it, so C = 0.
Am I right ?


texts: Will my DIY powerbank be safe? It will be charged using laptop chargers

texts:
I want to build a DIY power bank that can be powered using most types of laptop chargers. I do not have any background except personal interest and lots of videos and documents read online.
I need someone with more experience to please have a look at my circuit and let me know if it is going to work or if I'm building a time bomb :)

I will include all the component specs and links for convenience.

I will use a 3S10P battery pack built from reclaimed li-ion cells from dead laptop batteries.

I am hoping to have sort of a 'plug n play' functionality to avoid using switches (plug in charger to automatically start charging the powerbank, or plug in phone and immediately start charging it).

I am planning to use a relay switch for this to avoid a simltaneous charging/discharging scenario where a charger is connected when a phone is charging.

The relay is connected such that the Normally Closed (NC) contact is connected to the output (phone QC converters), while the Normally Open (NO) terminal is connected to the step down buck converter output (used for charging the powerbank). The control circuit is powered by the input of the buck converter. This way (at least the i think it will work), when a charger is connected, the output is disconnected so that I can't use the powerbank to charge my phone when it is charging.

Component links & specs:

NC temperature switch = 45 Celcius / 12v / 10A
USB Quick Charge buck converters = 6-32v / 3.2A
buck converter (12v output for charging battery) = 5-40V / 20A
LCD battery meter = 100V / 10A
BMS charger/balancer = 3S / 30A
SPDT (5 pole) relay = 12V 20A

What i need help/guidance with:

I want to charge/discharge each cell at 1A max. Is there a chance that the the circuit may draw more than this? Don't want to be too harsh on the reclaimed cells.
Temperature switches trigger at 45 celcius. Is that safe for li-ion?
Is there need for a cooling fan for the buck converter used to charge the powerbank? Output will be 12.6V 10A and input will depend on charger used. Most laptop chargers i've seen output between 12-20V at 4-10Amps
What changes/additions or general suggestions would you recommend?


texts:
I am building a simple motor control application, driving a series wound motor that runs on rectified 230VAC. Originally, it was controlled by a pendant switch connected to a 7 pin connector. The idea is to modify the setup inside the motor as little as possible and build a remote controller that connects to that same connector.
The connector serves the rectified 230VAC signal and I plan to use this as the source for the remote controller. This rectified signal must come back into the motor housing to drive the motor, and I will be controlling the connection using power relays.
I am planning to use a RF remote switch to control the relay coils, and I have two versions available: a 220VAC version, which does not work with the rectified signal, and a 24VDC version. I order to use the latter one, I need to reduce the rectified signal to 24VDC. What would be the easiest way to do this?
I have been looking into several topologies and found one that may be suitable:

For the circuit I am considering, the input must be the output of the bridge rectifier, which is what is available through the cable connected to the 7 pin connector, so there is no possibility of using a transformer before the bridge. This rectified signal must also drive the universal motor, but this will be done through another circuit.
In this case, this circuit must not drive a large current, only enough to drive the Load. This load is the RF remote switch and the relay coils connected to it.
I am aware that the R should be a power resistor that must stand several Watts of power dissipation. Considering a Zener voltage of 24V and a current of 5mA, with an input of 310VDC, the resistor value must be 59.2k and has a power dissipation of 1.5W. This is without taking into account the current consumption of the load, which at first glance should not be very high. I think a dissipated power of several Watts is an acceptable value considering that the series wound electric motor that it drives has a 1.5kW rating (EDIT: connected to the output of the bridge rectifier through relays, not driven by this circuit).
EDIT:
A more elaborated schematic of what I meant is the following (with the motor part heavily simplified):

I have been running some simulations and it seems that this topology is unsuitable. The LY2 24V relay I was planning to use has a coil resistance of 650 Ohm, resulting in a current of 37 mA when switched on. This produces a large voltage drop on the R1 resistor (and thus a large power dissipation). This causes the Zener to work below Vz. If the value of the resistor is reduced, the Zener voltage increases but also the power dissipation in the resistor.
The schematic is publicly available here.
As suggested in the comments, using a switched-mode power supply (SMPS) might be the way to go. I am still not sure if it will work correctly with a rectified voltage as the input.
EDIT:
It seems that this enclosed AC-DC converter is suitable for the application.


texts: What values / components do I need in this flip-flop circuit?

texts:
I need a circuit to make a relay toggle when pushing a push button. I found this circuit here:

It looks good for me - please tell me if it won't work.

I intend to work with a push button to Vcc and a pull-down resistor to zero on the input. I will push this button not very much (once in a few minutes max), so timing won't be a problem.

Now my questions:

What are R6 and R7 for?
What values do I need for the resistors?
Are 1N4148 and BC547B okay?
Can I use a 12V Vcc? My relay needs 12V.
Can I directly drive a relay from the output?
Do I need a rebounce circuit, and if so, can I use a capacitor for that, and if so, of what value?


texts: Is there a simple way to detect which connector is powered?

texts:
I have a circuit with two power connectors, J1 and J2.  I would like to be able to detect which one the power is coming from.  The trick is that the connectors need to provide power to each other.  See concept drawing below.  I can't think of any way other than putting in a series impedance and then using a diff amp to detect current direction.  Can anyone think of a simpler way?  Currently I'm using a jumper on the board to tell the circuit which one is providing the power.

The voltage is 24Vdc.  Current range is 20mA to 800mA.  Induced voltage drop can be around 1Vdc.

The reason is to have the circuit under power behave differently (master/slave) ie. Master is powered via J1, and the slave is powered by J2.

simulate this circuit – Schematic created using CircuitLab


texts: Spurious microwave emissions perhaps coming from conducting TRIAC controlling AC power?

texts:
I have a TRIAC switch on an 240VAC single phase AC line.  There is voltage on the gate as specified, there is a small dead band near zero.  I.e. it is conducting as expected.

However, I'm picking up spurious emissions in the ~6 GHz range. Is it possible that this is coming from the TRIAC switch circuit?

Has anyone measured a spectrum, using an instrument that measures out to that range, of that AC waveform with the dead band?  Are there residuals that high in frequency?

Would a reactive load with a conducting TRIAC somehow cause it to ring?  Has anyone seen that happen?


texts: Buck Controller ICs: Does the rated input voltage range limit the buck circuit supply voltage?

texts:
All of the buck controllers I found on the internet (e.g.; LM5141) assume that there will be a single input supply voltage in my circuit, and that voltage will be both supplying the IC and the buck controller circuit.

However, I want to supply the IC from a separate voltage source, and supply the buck circuit with a higher voltage (higher than the maximum allowed input voltage of the IC) as seen in the schematics below.

The input voltage of the power

My basic electronics knowledge says that this circuit is feasible since the IC won't see/feel the high voltage (e.g.: the 400V). Is there anything that may go wrong in a circuit like this?


texts:
I am designing a PCB, and it needs to have a right angle tactile switch. I am going to use a through hole, since it should offer added strength compared to a surface mount.

I am looking at the data sheet of this switch: Datasheet PDF

Looking at the schematic, pin 1 and 2 are the switching pins. It doesn't specifically say which pins are 1 and 2 however. From past knowledge, I assume those pins are the two inner ones.

Assuming I am correct, the outer pins just connect to each other, to add strength to the switch. Is it best practice to solder them both to the ground plane? Or just have an unconnected copper trace for them? Or just a hole, and leave them unsoldered?

Thanks!


texts: One-Line Diagram Standardized Symbols Information

texts:
Good day, people. I'm trying to get into electrical substation design and I'd like to know which standard sets the rules for substation One-Line Diagram Symbols .

Any ideas of where can I get that information?

I've already found IEEE Standard C37.2-2008, which is the device number standard of Directional Power Relays, Distance Relays, etc.

Regards,

F. Alvarez


texts:
I'm using a 7555 timer in monostable configuration to control a load of about 1A.

If I disconnect the 1A load or use a bench supply it works fine, but the drop in voltage from the batteries seems to be preventing the timer from resetting after the expected duration. The discharge pin voltage levels out at the control pin voltage but the timer doesn't reset.

I'm using 3xD batteries which provide about 4.5 V open circuit and 3.7 V with the 1A load.

Not sure what make of timer so can't confirm its minimum working voltage.


texts:
Varying input signal I want to select delay line based on the time period of input and tap out the output of delay line to input to Multiplexer.
For Example: Input Time period 1ns the input to Mux from delay line 1 should be selected and for input time period 2ns delay line 2 should be selected to input of Mux.

How can I control the output of Mux from the input from delay based on different input signals?


texts:
I am replacing a power distribution box that has 125A inlet and 16 No. 16A outlet sockets with earth leakage and overcurrent protection (16 No. 25A 30mA RCCB and 16A MCBs). We are fitting contactors fitted to times to prevent closure of the circuits at the same time, the recommendation is to use 4No. 25A TP contactors, however the previous design used 16 No. 20A 4P contactors (1NO+1NC).
I am unsure of what the difference is (other than the neutral) and why you would pick one over the other and what would be best for my situation.


texts:
We are specifying a system to use power over coaxial cable, that will transmit SDI video.

Is there any standard (IEEE or otherwise) for implementing it?


texts: Do you need to solder the center point in this type of BGA chip?

texts: I have the following chip. I'm not sure if its called a BGA chip or not. I need this chip replaced and I'm able to remove it using a hot air station, but I would like to know if I require soldering the center pad that is underneath the chip. Is this point usually used for important data that needs to be read or is just mainly for securing the chip with glue?


texts: How a solar charge controller can work on both 12 volt and 24 volt

texts:
Please excuse me for my silly question, I have basic understanding of electrical circuits.

I came across a solar charge controller which was rated for both 12 v and 24 v. My understanding is that charge controllers work by cutting off beyond a particular voltage (like beyond 14.4 volt for 12 volt charge controller). So how can such a charge controller "figure" out the attached battery system voltage?

If the answer requires a diagram, I'll be happy to look into that, I can understand basic electric circuits (involving diode, cap, resistor, etc)


texts:
I would like to use an HS-5035HD in one of my projects. Unlike most servos I've worked with that run at 4.8V-6V, this tiny motor only runs at 4.8V.

I have a 5V regulator in my circuit for powering my microcontroller and it would be great if I didn't need a second regulator. I'm wondering if there will be any actual detriment to running this motor at 5V instead of 4.8V of if 0.2V is within the motor's tolerance.


texts: Triphase servo motors and amplifiers from different manufacturers: can they work together?

texts:
I'm a newbie here and more generally in electronics. I'm offered used industrial equipment's that would theoretically be of great use for several projects we have in our workshop. More specifically, included are AC servo motors and a set of amplifiers and control. But it seems the motors were parts of different machines and are of different brands.

Is there any kind of interchangeability between such components from different manufacturers so that it would be reasonably feasible to get them to work together?

If the answer is yes, I would start investigating for relevant sources of information, or online guidance, on the net; mostly that I have been offered more units in case I'm interested. Otherwise, I would avoid investing too much time in trying to use this equipment.

I've spent time searching for info about this on the net but ended up with conflicting answers.

Wiki says: "Although many servo motors require a drive specific to that particular motor brand or model, many drives are now available that are compatible with a wide variety of motors ..." but I didn't find any lead about that, only brand-to-brand combinations. Furthermore, the best solution in my case would be to bundle my motors and driver together (if possible).

Any information greatly appreciated.

ps1: some pics of the equipment's attached

ps2: I am located off the beaten tracks and closest official technical support is 700 km away.. ;)


texts: How to connect the oscilloscope to a circuit

texts:
I am learning how to use an oscilloscope and I have just seen this picture in my textbook:

I'm not very sure, but I think the arrangement of the probes is incorrect. Isn't the alligator clip connected to the ground already? This will cause a short-circuit and it would damage the oscilloscope, wouldn't it?

Thank you


texts: Using two NPN transistors to form an AND gate

texts:
I'm a little puzzled by this schematic and am wondering if this is correct?

When I wire this up with 2N222 transistors and supply 5V at VCC with all 10K ohm resistors, and A and B are GND, the meter measurement at OUT is 0. If A and B are VCC, then OUT is close to VCC.  All good. Now if B is GND, while A is VCC, OUT is GND, also good. However, when A is GND and B is VCC, I see approx 2V at OUT. I was expecting GND. Is this because the collector on the bottom transistor does not have any voltage and current is flowing from the base to the emitter?  If so, is this schematic incorrect for an AND gate?


texts: Why is MATLAB a worthwhile investment in electrical design?

texts: Is MATLAB a worthwhile investment when developing semi-standard circuit designs? such as fitlering, DSP, power supplies, usual things we all encounter. From what I have read and used, it provides great filter design, easy interface for mathematical calculations and some block level design using Simulink and some ultra-specialist stuff.


texts:
I want to make a circuit to drive out a 48VAC 10mA 60Hz sine wave signal.
 I was thinking that I could generate a waveform with a microcontroller to feed it to an opamp then to a audio transformer
 Would this work?
I wanted it to he handheld, so I was thinking about sourcing the circuit with a battery. Haven't thought to much about the size.


texts: How to simulate headset button presses (TRRS jack) using a MCU?

texts:
I have a little project where I'm trying to control the music playback (play/pause/next/...) on an Android tablet from a Microchip PIC18F MCU.

The tablet has a TRRS mini-jack interface for sound output (ground/left/right audio) and also mic/buttons input. This interface is mentioned in other questions and well described in the Android Headset specification:

Basically, each button is connected in series with a resistance of a known value (or rather within a certain range). When a button is pressed, the corresponding circuit is closed and the phone can detect which button was pressed (presumably through some sort of ADC of the voltage level at MIC input).

Now, I would like to have my MCU simulate the various button press, but I'm not sure on how to proceed... basically I need to create a digitally controlled resistor that can take a set of given resistance values.

At first I thought about outputting specific voltage levels at the MIC input (for instance using a PWM output on the MCU), but I don't think that's a very good/robust approach since I don't exactly know how my tablet detects the button presses and also I would like to avoid making my circuit tablet-specific.
Currently, I'm thinking about a solution using the resistors connected in series with some small bipolar transistors used in switching mode and controlled by the MCU that would replace the buttons.

What do you think about this idea? Could it work? Do you have any better idea on how to proceed?

Thanks in advance for you suggestions!


texts: How to use a proximity sensor with a solenoid

texts:
Could you please help me with the following issue. It is a basic problem but I need help anyway. Please refer to the picture below. .

In fact, I would like to use a proximity sensor in order to action a solenoid (a push pull button) when an obstacle is close to the sensor there is a 5V voltage between A0 and GND which I would like to input it to the selenoid to action it. However, when I try this circuit, the solenoid is not actioned. When replacing the solenoid with a LED, the voltage is not equal to 5V (it is equal to 2.4V).

Could anyone help to overcome this simplistic issue please?


texts: Please help with safety of this circuit. Safe to plug in?

texts:
I have been working on this circuit as a project for school for a few months.

Here is the schematic

It is a pulse generator that produces 100ns pulses at 220VDC. These are used to drive an ultrasonic transducer that is represented by the 50 ohm resistor between the differential probes. Cadence simulates the circuit exactly as I predict, so I am not worried about finding any surprises other than shock hazards.

Here is my circuit

I have a few questions that I am too paranoid to trust google with.

I am going to buy wood from Lowe's to make a case for this circuit. Since there is no metal chassis, do I need to solder the green earth-ground wire anywhere in my completed device? I know that it cannot be soldered to the ground of my circuit, which is the piece of copper tape on the back side. The Vpulse ground will also be separate, as it will be MCU ground. If it is necessary, I have more copper tape that I could stick somewhere within the case separate from the rest of the circuit.
The datasheet for my isolation transformer does not specify where the white wire 'shield' should go. Googling shield I found that it is usually connected to ground,but is not necessary. I could not get the Cadence simulation to work with the center-tapped transormer, and instead used two coupled inductors as shown in the schematic. Is leaving the shield floating okay?

Are there any other things I should be worried about before plugging it in?

Datasheet of Isolation Transformer:
https://www.alliedelec.com/m/d/72306b3400a5a118df03c1c122b42c87.pdf


texts: Quotes for Low volume (>500) LCD displays

texts:
I am trying to find quotes for low volume displays, Graphic lcd's specifically, but I am interested in touch screen panels too. I found Vishay but cannot see any prices anywhere. I am curious what the big name companies do for their graphic LCD's, and how they determine what lcd to use. Do they fabricate their own displays, or purchase the displays from other companies?

Also, any opinions on how to choose a display for a low volume product?
What were your past experiences with choosing a graphic display, and what advice can you give?


texts: how to resolve mismatch between PWM resolution and sensor resolution?

texts:
I have an application that uses a high resolution sensor. The actuation loop runs on this sensor's feedback. Thus, the PWM resolution is limiting my achievable resolution in the actuator's movement. This seems like a common enough problem. Is there any standard way to get around this?

One way would be to amp up the PWM resolution by using fractional delays or increasing PWM clock's frequency. But assuming I have done all this, is there any other way to get a better PWM resolution?


texts: Are there any gotchas to using Safty Capacitors (X1/X2 box style) in the construction of a filter?

texts:
I guess this is just not done for whatever reason.  I hit Google and even after over 20 mins could not really find any information on point.

I've got a fair amount of .47uF and .68uF X1/X2 Metallized Polyester Film(I've got data sheets on a couple of them, these are all box) safety caps.

I want to use them to create a DAC reconstruction filter.  I have not yet decided on the topology though.  I'm thinking a 3 to 5 pole LC combined with a 3 pole Sallen Key active. I mean the caps would be perfect, high ratings, good D, not ceramic(The ceramic NP0 would be too small).

If they were not rated, I would not think twice, but I'm just wanting to make sure they won't cause problems based on their construction.  Was there something done to enable them to be rated that would cause problems.  The datasheets does not say, nor kind I find/see any complaints.

Ops forgot a data sheet:Okaya PA Series

NOTE: I added the x-capacitor tag, but I still feel the safety-capacitor tag would be better, or maybe a link.  I think those Y caps feel discriminated against..:)


texts: The crystal oscillator used in UART is of 11.059MHZ, why?

texts: I want know UART crystal used in it why it is of 11.05MHZ, and why we use it.


texts: Why has this configuration chosen for feedback?

texts:
I'm a newbie in electronics and Trying to understand and build this circuit. would somebody tell me the rule of R1 & C2 in this circuit and their magnitude effect on the controlling of process.why didnt feedback start just after the output of opamp?How could i find the transfer function between the voltage output of Hall effect sensor and the voltage output of MOSFET drain?

The schematic is the circuit of a magnetic levitating tool at:

http://www.bis0uhr.de/index.htm?http://www.bis0uhr.de/projekte/schwebekugel/english.php%99https://www.youtube.com/

Thanks so much


texts:
Is it ok to use an "ordinary" via to connect the Exposed Pad of an TQNF package to ground, as shown in the following picture?

I am using eagle. DRC generates an "overlap" error, is it ok to ignore this error?

Can this design cause board assembly issues (I'm planning to do machine assembly)?


texts:
I am facing an issue of bytes being copied in a reverse order when I compile code using ARMCC.
For example :

short int dest;
short int src = 0x0010;
memcpy(&dest,&src,sizeof(short int));

The value in the dest when i look into the memory display is shown as 10 00. I wonder why doesnt it place the values in appropriate bytes in the destination. To over come this, I have to use an array and copy value byte by byte.

Is there a solution to this issue ? or it is some problem in my code.


texts: Ni-MH battery charging issue - custom built transformers, LM317 gets warm

texts:
I had one variable voltage power supply built and I have been using it frequently.

Although I had no issue until charging Ni-MH and Ni-Cad batteries with this power supply. Lead acid battery, lithium-ion charging working pretty well. But it seems like Ni-MH and Ni-Cad charges gets too hot for linear regulator LM317. I'm currently charging each cell with about 5 volts and it consumes way too much current compared to other batteries. What can I do now?