texts: How do I make a small handheld from scratch that I can put a simple homemade game onto?

texts: Alright, some how I couldn't find really anything about this on the internet so far, but I'm trying to find a way to make my own small simple handheld device with a small screen from scratch and then find a way to program a very simple game onto it. Kind of like those small handhelds that were at McDonald's that just had a few buttons, and the game was very simple to play. Anything will help, Thank you.


texts: What can I use as an equivalent component to these in Eagle?

texts:
I just wanted to ask you if I can use SN74154N as a library and, hopefully, it would be same size (pins, etc..) as my original component MH74154.
Also, what component would you recommend instead of MH7404 hex inverter in Eagle? It should also be the same width, pinout number and so on..
I want to use all of these components in my PCB project.


texts:
I am designing a measuring instrument powered by a Li ion Cell, I need to display remaining battery capacity on it, so I was wondering what is good or lets say widely used method.

Should I use full fledged Battery fuel gauge IC instead of just measuring battery voltage to display remaining battery.

My second question is, since current draw of my instrument would be fairly constant throughout the run, so is it possible to estimate capacity from Battery voltage and current draw?


texts: How to arrange many thermal sensors in series?

texts:
Is there a kind of thermal sensor that only changes resistance if it is above 50'C and that can be wired in series?

I want to wire 50 thermal sensors on 50 batteries so that i can see if any one of them gets too hot.


texts: How to detect the power source when multiple power sources are available?

texts:
I have very little background in electronics, I'm from software background.

I'm interested to design a system in which there is an 8-bit micro-controller which should get powered from two different sources:

From a battery (in Field mode) and
From a USB port (in Factory mode)

Further, the software running on the micro-controller when it gets powered, on the basis of the power source, should enter into respective modes of operation. When powered from battery the algorithm should in run in Field mode and when from USB in Factory mode.

If there are simple ways to do this, then it will save a ton of my efforts to find out other ways of detecting where the device is.

Can anybody help me understand how to achieve this?

Thank you.


texts:
I want to add a reset button to the MCU in a PCB that I am trying to design. I came across some SMD buttons, but I wonder what is the difference between them?

One of them has a ground terminal. What is the purpose of that and can you possibly give a usage case for the button with ground terminal?
A normal reset would just require button with 2 pins (AFAIK):


texts: What could be this "transient electric deviation"?

texts:
On August 7th, 2011 a lightning hit a transformer powering one of Amazon EC2 facilities in Dublin. The status report said

  Normally, upon dropping the utility power provided by the transformer, electrical load would be seamlessly picked up by backup generators. The transient electric deviation caused by the explosion was large enough that it propagated to a portion of the phase control system that synchronizes the backup generator plant, disabling some of them.

Okay, the transformer was hit and exploded and became inoperational. But what's this "transient electric deviation" that prevented generators from starting?


texts:
My question is with regard to establishing regulation using values taken off the characteristic curve. I have \$I_{kn}\$ = 1.8mA and \$V_z\$ = -8.2V. How can I determine the minimum input voltage for regulation to be established?

Do I have to calculate \$R_z\$? I am not sure what I need to calculate in order to figure this out.

Thanks.


texts: How can I read my transistor part number?

texts:
My transistor has this part number:
DXG40N65HSEU
Yet I am not be able to get another.
Can you help me to read its part number so that I can be able to check for an alternative?


texts: Adapting the 74LS170 open-collector "register file" to active-high TTL input

texts:
This is a question related to swapping a 74LS170 4 x 4 register file chip for a 74LS173 single 4-bit register. In the other question I wonder if there are even simpler ways to Turn a positive clock edge into a negative pulse to make a 74LS170/670 register file synchronous. But here I need to deal with the issue that the 74LS170 is an open collector chip (and for now I am unable to get the '670, which is a three state).

I read a number of things about open collector, and especially the other pretty decent entry here Understanding Proper Implementation Of Open-Collector. However, I think I need to get spelled out a clear "yes" or "no" answer to my following doubt:

If you want to drive further TTL inputs from open-collector output, you need to consider your signals effectively inverted.

In other words, you can tie the open collector output pin high, and then when it is active it will be pulled low through the enabled transistor. There is no way to source current from an open-collector output.

Hence, if I want to use the 74LS170 as an actual register file, I need to also use an inverter for the 4 bits. It just so happens that if I actually want to turn the 74LS170 into a synchronous register whose load is driven by the positive clock-edge, I need the inverter anyway, along with an OR gate. So there simply is no other way.

simulate this circuit – Schematic created using CircuitLab

Or is there?

As a bonus question: the '670 was developed much later, supposedly, and it has 3-state output, so it no longer effectively inverts the output. But why in the world would they not have driven that by a positive clock edge, instead of using the pin for the 3-state logic? I mean, nobody could have just dropped in the '670 for the '170 because the sense of the output bits are inverted. Why even bother with the 3-state then? I feel that the answer to this question might help me appreciate the annoying situation with the open-collector need for inverters.

Or, another one of those pleading questions: was the open collector output so much easier to do that they would determine that it's better this way than to let the user add their own (power) transistor to adapt to voltage and current levels?

And finally an idea: perhaps this explains the odd customs with these active-low signals on most "load" or "write enable" pins of most flip flops and SRAM and EEPROMs? And from there, perhaps, by using open-collector OR gates instead of normal TTL outputs, I effectively get NORs and other inversions which might simplify my clock edge detection IC overhead?

Yet another possible explanation: if the register file's output is expected to be output onto a bus, were the original designers expecting that it be connected as an effective NAND gate with the other devices on that bus? Still can't quite see the rationale for this.

Final whining question: so why in the world would I even want to use the 74LS170 (even decades ago) when with all the work I need to go through I can just as well adapt the 74LS189, fitting it with a clock edge detector and the inverter, using the same number of chips I get 16 instead of just 4 registers? (OK, because I can not read from one address and write to another in the same cycle, fine.)


texts:
The reason for these questions is I'm using these programmers to test a circuit boards with test firmware so I'm trusting the pickit3 to report programming failures without damage to the USB port and the pickit3. In terms of protection of the devices the best I can hope for is that the programmer to switch off power in under 1ms should there be a high current draw. Of-course if something strange like the Vpp line shorting somewhere that could send a high voltage to any of the lines.

Is it possible to damage a pickit3 or pm3 if powering target from the programmer with 5V?
Is current protection bulletproof when there are no external power sources no matter what permutation of fault exists on the target?
If current protection works then how long does it take to switch off the power?
Will the Pickit3 stop what it's doing no matter when, during programming, if the over-current occurs?


texts: Diff. Amplifier with Single Supply Opamp - Strange Behavior

texts:
I'm playing with some "precision" (as claimed by manufacturers) opamps and DACs to test how "precise" they are.

So, the components I'm testing are:

DAC7612U by TI: A two channel 12-bit (1mV/LSB, up to 4095mV) DAC with internal reference and buffered outputs.
OPA2335 by TI: A single-supply opamp with very low input offset voltage (5uV max).

For testing purposes, I've built the following circuit (Note that all resistors are 0603 case SMD ones with %1 tolerance and the output sections of DAC is taken from datasheet as they're shown):

simulate this circuit – Schematic created using CircuitLab

As you can see, the first block after the DAC is a differential amplifier with unity gain and the last block is a non-inverting amplifier with a gain of 1 or 2 (depending on the state of the analog switch, 1G1357). \$VO_A\$, \$VO_B\$, \$V_{diff}\$ and \$V_{buff}\$ are test/measurement points.

And finally, here are what I got:

When I reset (zero) both outputs of DAC, I measure about 1mV on both \$VO_A\$ and \$VO_B\$. Quite normal, because zero-scale error is given as 1mV in the datasheet. And, as expected, voltages on \$V_{diff}\$ and \$V_{buff}\$ are in uV range. No problem at this point.
When I set OUT_A to about 500mV and leave OUT_B untouched, the measurements are correct on all test points.
This is the one that I have question about: When I set OUT_A to about 3500mV or higher, and leave OUT_B untouched, I measure about 4mV on \$VO_B\$, but it should be about 1mV! If I disconnect the differential amplifier, the measurements are correct on both \$VO_A\$ (the code I loaded in mV) and \$VO_B\$ (about 1mV). If I reconnect the differential amplifier and use lower resistances (e.g. 15k) for all of R1, R2, R3 and R4 then the measurements get worse: \$VO_B\$ increases to 8mV even if the loaded code is zero! One more interesting thing: \$V_{diff}\$ shows \$V_{diff} = VO_A - VO_B + V_{err}\$; where \$V_{err}\$ is the error voltage that I measured on \$VO_B\$ for \$VO_A \ge 2500mV\$ (It's 0mV for \$VO_A \le 2000mV\$).

How can it be? Why does this happen? What should I do?

Sorry for long post. Hope I could explain the problem.


texts:
I am working on a tremolo guitar pedal circuit. A tremolo pedal basically attenuates the guitar signal using a pattern. Most tremolos use a combination of LEDs and LDRs to do this, but since I do not have any LDRs at the moment I chose to design one using a digital potentiometer.

For simplicity I have not included the digital side of the circuit. This only consists of an Arduino Nano, connected to the digital potentiometer using SPI.
I have breadboarded the circuit and it works, except it makes a ticking sound. It is very noticeable on the high gain setting on my amplifier. At first I thought it was an issue with the Arduino, but after removing both the Arduino and the digipot -- and replacing the digipot with a resistor -- the issue persists. I have no idea what is going on. Could it be an oscillation of some sort? Should the schematic work and lies the error in my breadboarded implementation?
Thanks in advance!


texts:
simulate this circuit – Schematic created using CircuitLab

Applying KCL:
I get, (0-Va)/2R + (0-Va)/R = (5-Va) / 2R
Is this right?

The resistor R is actually connected to GND, not drawn on the image.


texts:
I've recently bought an Olimx ARM-USB-OCD JTAG programmer but I've had difficulty getting it to work.

My primary system is linux, but I've tested it in window with no luck there either. I'm using OpenOCD to communicate with the device, but it does not detect the ftdi chip on the programmer.

I suspect the hardware is dodgy, for two reasons. The programmer has the ability to power a board at 5V,9V or 12V, but when I measure the output voltage it is only at 0.7~1V (when connected to USB, tested on 3 different computers and one usb hub); additionally, when conncted to linux, the ftdi chip is detected, but it connects and disconnect quickly leaving a number of errors in syslog.

My questions are (and I'm most interested in anyone who has the same programmer): is the hardware broken? If not, what am I likely to be doing wrong?


texts: Can optical fibers transmit in both directions simultaneously? Both single mode fibers and multi mode? What about if they we choose non-interfering wavelengths?


texts: Is there a standard for schematic power symbols?

texts:
I notice that some schematics use a single, labelled, symbol for power that looks like an uppercase letter "T", while others use varying symbols (mostly types of arrow) to indicate various voltages; I consider the latter to be more readable and useful and I'd like to adopt it with my own schematics.

My question is, is there any standard or de-facto set of symbols for the various voltages? Is it reasonable to create my own scheme if I'm consistent within my own use?

My primary goal is to clearly indicate different voltage levels on the one schematic; I often work with a largely 5 V DC circuit that has one or more pieces using 3.3 V. Many of the voltage-specific schemes don't seem to differentiate between these voltages.

In any case, I will ensure that every power symbol on every schematic sheet is clearly labelled with the voltage; I completely understand that a symbol is not sufficient for describing power rails.


texts:
I am using a PIC16F877A and am reading its ADC value and sending it to the serial port. I am blinking an LED with it so that I can determine whether or not the program is stuck.  Unfortunately, I cannot see any data on the port via Hyperterminal.  However, if I test my code in Proteus, I see data on the virtual terminal.  I know the hardware is designed correctly because it is a commercial testing kit.

I think there is a problem with the crystal settings.

I have also confirmed that the cable is working, because I use the same one for my programmer and this hardware.  I am using the Mikro C pic compiler, with the frequency set to 4MHz.  I tried to edit my project and set the oscillator to HS as well as XT, but the results are the same.  What is wrong?

char text[7];

void main() {
  unsigned int adc_value =0;

  UART1_Init(9600);               // Initialize UART module at 9600 bps
  Delay_ms(100);                  // Wait for UART module to stabilize

  ADCON1 = 0x80;              // Configure analog inputs and Vref
  TRISA = 0xFF;               // PORTA is input
  TRISC  = 0;                 // PORTC is output
  TRISB  = 0;                 // PORTB is output

  PORTB = 0;
  UART1_Write_Text("Start");

  Delay_ms(100);
  do
  {
  PORTB.B3 = ~PORTB.B3;

    adc_value = Adc_Read(0); // Get results of AD conversion
    IntToStr(adc_value, text);
    UART1_Write(10);
    UART1_Write(0x90);
    UART1_Write_Text(text);
    UART1_Write_Text("\r\n");
    Delay_us(200);
   // PORTB = adc_value;         // Send lower 8 bits to PORTB
    PORTC = adc_value >> 8;    // Send 2 most significant bits to RC1, RC0

    Delay_ms(100);
  } while(1);
}


texts: How do I read the state of 3 output pins on an Arduino UNO and then NAND them together?

texts:
So I am working on software to control a H8 inverter. I got code that does SPWM for a 3 phase inverter online. I then applied a software NAND gate on 3 outputs from the Arduino UNO and this is the result I got:

and this:

I used a hardware NAND gate and I got this:

//-------www<electronics-project-hub>com--------//
#include <math.h>
int Output1 = 11;
int Output2 = 10;
int Output3 = 9;

int Output4 = 6;

int potVal = 0;
float A = 0;
float B = 0.104;
int Freq_IN = A0;
int var1 = 0;
int var2 = 0;
int var3 = 0;
int var4 = 0;
int var5 = 0;
int var6 = 0;
float Phase1 = 2 * PI / 3;
float Phase2 = 4 * PI / 3;
float Phase3 = 2 * PI;
boolean toggle = true; // true = Enabling Serial Plotter Output
void setup()
{
  Serial.begin(9600);
  pinMode(Output1, OUTPUT);
  pinMode(Output2, OUTPUT);
  pinMode(Output3, OUTPUT);
  pinMode(Freq_IN, INPUT);
}
void loop()
{
  A += B;
 analogWrite(Output1, var1);
 analogWrite(Output2, var2);
 analogWrite(Output3, var3);

 digitalWrite(Output4,!(digitalRead(Output1)&&digitalRead(Output2)&&digitalRead(Output3)));

 if (toggle == true)
 {
    Serial.print(var1);
    Serial.print(" ");
    Serial.print(var2);
    Serial.print(" ");
    Serial.println(var3);
 }
 var4 = 126 * sin(A + Phase1);
 var1 = var4 + 128;
 var5 = 126 * sin(A + Phase2);
 var2 = var5 + 128;
 var6 = 126 * sin(A + Phase3);
 var3 = var6 + 128;
 if (A >= 2 * PI)
 {
    A = 0;
 }
 potVal = analogRead(Freq_IN);
 delay(potVal);
}
//-------www<electronics-project-hub>com--------//

I would like to point out that the software NAND output stayed ON all the time. The hardware NAND output varied, which is the result I am trying to get.


texts: What is the correct command sequence for microSD card initialization in SPI?

texts:
I am trying to interface a microSD card (2 GB, Kingston, Sandisk) with a Silicon Labs C8051F931 controller.

I am very much confused about the sequence which I have to follow for initialization. In the book SD Card Projects Using the PIC Microcontroller, page 135 mentions:

  The steps to switch the SD card into SPI mode should therefore be as
  follows:
  Power-up.
  • Send at least 74 clock pulses to the card with
  CS and Data Outlines set to logic “1.”
  • Set CD line low.
  • Send 6-byte CMD0 command “40 00 00 00 00 95” to put the card in SPI mode.
  • Check R1 response to make sure there are no error bits set.
  • Send command CMD1 repeatedly until the “in-idle-state” bit in R1 response
  is set to “0,”
  • and there are no error bits set. The card is now
  ready for read/write operations.

I tried this, but I am getting 01 even for CDM1. 00 is expected.

Also here I see a different command sequence where he sends CMD8 after CMD0. But the book says I have to send CMD1.

What is the correct sequence?


texts: Uniformly illuminate an array of LEDs: how to get the most homogeneous output?

texts:
Please note: this question refers to the electrical engineering part
  of the design, optical configuration is not request (advices are
  however  welcome)

I'm trying to design a LEDs lamp with an homogeneous output for a radiometric experiment (so I don't care about energy consumption but I would like a safe prototype, so I prefer a low voltage, that works decently even if is not the best way to do it). So far I've seen different approach: in this video seems that for build an LEDs matrix I should use a resistor for every LED. However I think that parallel arrangement does not produce an homogeneous output, (i think some LED will be brighter...) so I think Sphero answer to my first question could be the best alternative, however I don't understand how to design the last part of his circuit (op-amp, BJT... ) furthermore I think that a long series could have the same effect due to the non-ohmic nature of LEDs (Am I wrong?). So I've tried a different approach but I don't know if it is right. Here is the schematics:

simulate this circuit – Schematic created using CircuitLab
Assuming that LED's If=100mA and Vf=1.35 V  and I have a 12 V source, if I'm not wrong I need:
$$ R=\frac{12V~-(1.35V \times 2)}{0.1A}=93\Omega$$ so I can use a 100 Ohm resistor (I don't know why I can't run the simulation, but power consumption should be under 4 W).

My specific needs:

lamp from 12 to 22 LEDs
not necessarily high output so LEDs can be light even with lower current e.g. 70 mA
not high voltage I want a "safe" prototype
power consumption is not a problem, so can be inefficient, I want only homogeneous output and something that don't auto-ignite or burn thing that get in touch (e.g. my hands).
The lamp will not turn on for long period of time, typical working session could be about 5-30 min.

Which is the best way to have the same brightness from all the LEDs without use a dangerous voltage? And just for curiosity Which is the best way at all, no matter voltage or power consumption?


texts: Can an LPC1343 accept its initial program over USB?

texts: The LPC13xx datasheet suggests some clock setup is necessary to use USB. Does the chip's built in boot loader make it possible to load the initial program over USB, or do the clock multipliers have to be configured with JTAG first?


texts:
I need to drive a single n channel mosfet. To do that, I choose LTC1154 Mosfet driver. The first question of mine, power of the driver is supplied by 4 lithium-ion battery cells. Normally, with time, cells are discharged. Does the given gate voltage by driver decrease or could it be constant? Second question of mine, as you can see in the picture, there is a typical appliction for MOSFET. However,it is said 2.7A maximum. I checked the MOSFET that are used continious drain current is 14A and I can not find any limitations for LTC1154 driver. Can you explain me please?
Thank you. link is the datsheet of the LTC1154


texts: What type of solder is safest for home (hobbyist) use?

texts: I'd like to do some hobbyist soldering at home, and would like to make sure I don't poison those living with me (especially small children).  Lead-free seems necessary - what other features should I look for in solder?  Are the different types of solder roughly the same in terms of safety (breathing the fumes, vapor fallout, etc.)?  Is there more I should do to keep the place clean besides having a filter fan and wiping down the work surface when finished?


texts: Why is the gain of this LC two-port network infinite?

texts:
Consider the following two port network, where a voltage is measured across the output terminals (no current), and the input is connected to an AC power source:

Calculating the voltage gain of this circuit using the impedance divider rule for series components gives:

\begin{align}
\frac{V_{out}}{V_{in}}&=\frac{Z_C}{Z_C+Z_L}\\
&=\frac{j\omega L}{j\omega L + \frac1{j\omega C}}\\
&=\frac{j\omega L}{j\omega L - \frac{j}{\omega C}}\\
&=\frac{\omega L}{\omega L - \frac1{\omega C}}\\
&=\frac1{1 - \frac1{\omega^2 LC}}
\end{align}

Clearly when
$$\omega=\frac1{\sqrt{LC}}$$
then division by zero will occur and the gain will be undefined. Assuming I haven't made any mistakes in calculating the voltage gain, could you please explain to me how this can make physical sense. What would happen in real life if I chose all of the values so that division by zero occurred?

Apparently the value for the angular frequency shown above is the resonance frequency for series LC circuits. Is the following answer (my guess) correct: "The gain is 'infinite' because the circuit shown above has no resistance, so more and more energy is inserted into the circuit, as it resonates, building up energy, forever. In a real circuit, the gain would not be infinite, due to losses in the circuit."

EDIT: I recalculated, incorporating a resistor in series, and the gain function changed as shown below (no resistance in red and with resistance in purple). The graph shown is with R = C = L = 1, it just gives you an idea of the shape.


texts:
I posted this question before, but I am still struggling with this.
I captured a schematic and others in this time so it should be more clear to see what's going on.

I was given a custom board including Tiva C TM4C1294 + other components on it. Unlike EK-TM4C, FTDI2232d is applied on the custom board.

I have tried to configure ft2232 using FT Prog and programmed .bin into the custom board, but nothing works so far.

Here is a schematic for FT2232D interfacing TM4C:

Here is My Computer's hardware Configurations:

Here is how I set up using FT Prog:

I have chose other options but nothing works. According to the schematic Ch A is MPSSE mode

Also I have tried on different options, but...

For the Ch B, 232 UART and Virtual Com Port are selected.

As I program .bin into the custom board. It says "unable to find a target"
I am not sure what is wrong with it.

Thanks,
Jin


texts: Understanding Electrical Engineering with Analogies

texts:
Understanding concepts with analogies help can be a useful technique and hopefully this will help me better understand electricity and Electrical Engineering better.

Lets start with a simple water example:

  X volume of water starts flowing from a collector (battery) through
  the pipe with Y pounds of pressure at Z speed when it comes across a
  thinner portion of pipe (resistor).

Now, perhaps my physics knowledge is off but I would image that when it hits the thinner portion of pipe, resistance increases causing the pressure and speed of the water to increase but the volume would decrease. If this is correct, does that mean that the voltage and current increase but the number of electrons (what is the mass/volume analogy for electrons?) would decrease (and therefore power)?

Additionally, since electrons actually flow from negative to positive (electron flow), in contrast to conventional flow, does that cause this analogy to break down in a true circuit (especially with numerous components)?

Thanks in advance for the help.


texts:
I'm trying to "re-engineer" (the original designer doesn't manufacture the board anymore but they were kind enough to provide me with the diagram) a circuit that replaces an incandescent bulb with a LED, and it specifies a white LED "filtered" to 3000K. My question is, does somebody out there make a LED with an integrated filter, or do I have to add an external filter to the LED?

EDIT:
I should have probably said this in the beginning, but the LED is going into a light meter, which is probably why it's filtered down to 3000K. The meter is this one; http://www.jollinger.com/photo/meters/meters/sei_photometer.html

EDIT2:
Now I found the site with the exact thing I'm trying to build, there's definitely a filter on top of that LED. http://www.huwswebthing.talktalk.net/seiled.htm


texts: Wiring 16-pin USB-C jack to USB-to-UART controller

texts:
I'm using this USB-to-UART IC, and this 16-pin USB-C jack on my design.  I'm trying to better understand some of the USB-C spec, particularly related to pin mirroring and such.

On the PCB, should I be connecting both D+ pins to the D+ pin on the controller, and both D- pins to D-?  I understand conceptually how the pin mirroring works, but I don't understand if it's expected that all cables already have them cross-wired, or if that should be done on the PCB.  Conversely, if it isn't necessary, are there any pitfalls to cross-connecting them on the PCB?


texts:
Considering a monopolar HVDC system, with the ground as the return path.
I was wondering if the current path is physically speaking like the red one or the green one in the picture? I think it is like the green one, although if there are living beings in the middle, they can be thunderstruck by the current. The green one considers that the earth has a charge.
(It's strange to say that nobody has explained me this thing until now, and I'm a student at Politecnico di Milano, I'm following the Smart grid path and I am in the fourth year. Unluckily, these such things usually are not explained.) Do you know the answer?


texts:
How to find Vo of this pi model of FET amplifier?

I have to find voltage amplification (Av=Vo/Vi) of this circuit and output resistance Ro, so I need to find the Vo voltage. I found the expression for current id, but I don't know how to express Vo.
Could you please help? Thanks in advance.

(id-gm1Vgs1)rd1 + idRs1 + (id-gm2Vgs2)rd2 + idRs2=0

(id -gm1(Vi-idRs1))rd1 + idRs1 + (id-gm2(Vi-idRs2))rd2 +idRs2=0

if the calculation are made

id= (gm1rd1 +gm2rd2)Vi / rd1+rd2+Rs1+Rs2+gm1Rs1rd1+gm2Rs2rd2

this is the original circuit

simulate this circuit – Schematic created using CircuitLab


texts: more current needed in an electrical circuit

texts:
Currently, I'm doing my wind turbine electrical project. Let me get straight to the topic, wind turbine, with a small generator in it.  Lets say it can produce 2V and less than 1A . It is connected to an inverter to increase its voltage. Now my idea is to connect the output to a load, where I will need more than 30A. Do you guys have any idea on how to make this happen?
Or not necessarily to connect it to an inverter, anything to increase the current. I have many ideas to increase the voltage.


texts: For Multiple ADC circuits PCB layout grounding, why is "single point ground" important?

texts:
I am reading this article from Maxim on mixed-signal circuits grounding:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/5450

Everything makes sense to me until I read the "Grounding Challenge of Multiple Mixed-Signal ICs". It shows the following diagram to indicate that the cut plane technique does not suit for the multiple mixed-signal ICs.

They think splitting ground plane into analog plane and digital plane is bad for multiple mixed-signal ICs. The reason they gave is: there is no single point ground any more.

Why is single point ground important in this case?


texts: Using polarity reversal to limit voltage

texts:
My electrical experience is limited to ordinary soldering of resistors, pots, and relays to control my model railroad layout, so please excuse my lack of more advanced logic circuit and semiconductor knowledge.

What I'd like to do is reduce 7 volts to 4 volts on a particular track when a photocell trips a DC polarity reversal (½ amp max current). The idea is that a train on this track would shuttle back and forth in automated mode. I've installed the photocell device, which senses the train and reverses track polarity, causing the train to stop and run in the opposite direction.

The problem is that the track has a steep downgrade and  voltage needs to be reduced to 4 volts to avoid excessive speed going downhill. Of course, I can manually vary the track voltage at the transformer, but that defeats the idea of having the train continuously shuttle back and forth in automated, hands-off mode.

Any suggestions for a circuit that would block the 7 volts and direct the current flow to a resistor or pot limiting track voltage to 4 volts, when the DC current changes from positive to negative?


texts:
I have looked everywhere but haven't been able to find a decent answer. So here goes my question from the depths of my ignorance.

I recently bought a solar-powered charger and battery pack for traveling. I only noticed afterward that the output voltage of the charger is 5.5V.

I know that USB ports give 5V +/- 0.25V. My phone's branded charger's output is 5.1V (also via a standard USB cable running from the plug), with almost all USB-chargeable devices requiring 5V.

This leaves the question, can I use the solar charger for USB devices without worrying about damage? Would an extra 0.25V risk causing damage? If so, how large the risk, and why the hell would someone produce a solar charging device, with a USB output port, that pushes out 5.5V?!


texts: Are prototyping boards suitable for 200V?

texts:
I have some prototyping boards like this:-

It's a standard 0.1 inch pitch and I like them.  Is this suitable for a medium voltage of about 200 V DC?  I'm concerned that the voltage might just repetitively creep /jump between pads right across the board.


texts: How are low-noise transistors different from other?

texts: Yes, I know: they have lower noise levels. What I mean is how is this achieved? And I guess there must be a trade-off as well (otherwise all transistors would be made as low-noise?)


texts:
In a 120V AC motor circuit, a capacitor is wired in series with the start/auxillary winding.  I'm a beginner, but I think I have learned that the cap's function is to create a phase shift to enable start rotation. What is still unclear to me is where the cap should be located:

Is it:

Hot line voltage-----cap-------start winding-------Neutral.

Or

Hot line voltage----start winding------cap--------Neutral.

If the cap came after the winding, wouldn't the winding be energized a second time when the cap discharged its saturated negative plate when line voltage oscillated through zero? But maybe this is what DOES happen.  Can someone explain?


texts: Is 'carrier leakage from the active region' of an LED the same as 'reverse leakage current'? If they're different what are their respective physical origins?


texts: Implications and cause for static discharge

texts:
For months, I've had a potential buildup culminating in static discharge when touching the chassis of my macbook pro at ONE location. No source could be identified (no ground leakage – I checked with multiple multimeters at multiple locations in the office, happened with and without a grounded power supply, etc) and I concluded it must be the laminate floor and low humidity levels in the office. I ended up buying a humidifier and decided I would need to live with it.
It seems I have now identified the (potential!) culprit: a multi socket extension with a loose contact. The railing of the plug was not fully connected with the neutral wire. This was loose. However, there was very little discoloration (and hence spark buildup).

This was only noticeable months later, as the connection would sometimes fully break if another device was attached to the multi-socket extension, causing the faulty contact to move and hence cause all devices on the extension not be powered. No fuse blew, no device was noticeably harmed. After the second occurrence, I retired the extension and took it apart to investigate.
My questions:

Do you think this loose contact (not causing any disruptions, blackouts or the like) could be the reason for the perceived ground leakage?
None of the previously attached devices (used for 12+ hours per day over 12 months) are noticeably damaged; do you think there might still be the chance for long-term damage? Specifically, what are the implications of potential build up on the metal chassis of a laptop – which components would be damaged first?

Thanks!


texts: How far can I extend the leads of this temperature sensor?

texts:
I purchased this cigarette lighter unit that is a voltage meter, temperature sensor, and USB charger. The temperature sensor appears to be on a wire lead that comes out of the case.

I took apart the unit and its construction is very simple. I can solder to the circuit board if need be. What type of thermistor does this unit likely use? How far can I extend the leads of the temperature sensor and have the unit continue to give an accurate reading?


texts:
Found a nice guide on how to make a led turning signal for bikes based the 555 timer which contained this schematic:

But no matter how I do it, I cannot make it work.The leds won't blink.... What's going on here?

I'm using normal 12V-rated LEDs (used for car license plates)

The LEDs are not flashing at all, just are turned on...


texts: Subtleties of Boost Conver (Step-up Converter)

texts:
simulate this circuit – Schematic created using CircuitLab

Generally Boost Converter fault happens in my workplace and difficult to find the problem of converter. So I try to understand the logic of the boost conventer. I would be glad if you answer a few questions that be on my head.

1- How to determine the volt of the condenser at the output. Is the volt of the condenser at the output equal to the maximum induced voltage in the inductance? What will happen if I use smaller or bigger condenser?

2- How many Henry the inductance should be? In addition, some companies make thin wire with a lot of winding (48 Henry), while in some companies they combine 3 thick wire, and make little winding (4.8 Henry). Which is correct? What should be the wire thickness, what should we choose the number of turns (so Henry)?

3- As far as I understand, the factors that affect the output voltage "Vout" are:  the input voltage "Vin", Inductan "L", Mosfet gate frequency "HzGate" and the Duty Cycle of the Mosfet Gate leg "λ". What is the formula of the output voltage according to these parameters.


texts:
I was wondering if it is possible to create a bluetooth device which would have a LCD screen and some memory (1kb) for making and receiving calls.

From my research ( and I am far from an EE, but trying to learn as I go) i found that arduino doesnt support HFP or HSP.  What Id like the device do is, go through a small list of numbers on lcd, choose one and make a call through the bluetooth connection to a smartphone.

Any help is appreciated.

EDIT. so while looking online a found a BT module RN-52, has both SSP and HFP/HSP, and when looking at the PDF for the RN-52 Evaluation kit i found on page 24 that it has a command to call any phone number that it is given.
http://ww1.microchip.com/downloads/en/DeviceDoc/rn-bt-audio-ug-2.0r.pdf

My question now is. Can it be connected to an arduino uno, so that it can send a number to the rn-52, so it can call it?

thanks


texts: Looking for a long-distance (~1km) physical layer

texts:
First of all, I have to say my knowledge on how networks work physically is limited. I am working on a project to interconnect farming equipment over fairly long distances, at a maximum of 1km, more or less. I looked at RS-485 but I don't entirely understand the need for a common ground, and I'm not really sure if it is needed or not. Basically, I am looking for the cheapest reliable way to connect this devices on a bus-like network over such long distances.

Is the common grounding needed? If so, how can it be achieved?


texts:
I do not understand the concept of convolution. If possible could you please explain in layman terms so that I can solve this question.

What is the h(t)?


texts: Reducing Inductive Kick when Switching Audio Transformer

texts:
I have a circuit where I'm switching the primary of an audio transformer using relay NO/NC contacts. A partial schematic is shown.

The problem is that I'm getting inductive kick whenever the contacts close to switch off the input. This can be seen in the scope image below and is audible as a "pop" at the output.

I have the high pass on the secondary and impedances right where I want them, with a corner frequency at 99.6kHz and slight underdamped peak at about 56kHz. That gives a relatively flat response up through 20kHz. Part of the issue is also that the input should be able to handle 3Vrms, and the spikes are not that high (generally 2-4V). I've read that a snubber circuit is commonly used for this, but not sure where to start. If treated as a low pass filter, the large 220uF cap as part of the snubber would need a tiny resistor to pass audio frequencies, and I think would throw off the impedances.

Would appreciate any useful input.

UPDATE: So after considering the responses and researching mute circuits, I realize the above circuit drawing demonstrates what I wanted to accomplish but is horrible in implementation. Even with make-before-break contacts, trying to break both sides simultaneously and have them do so at the same time to prevent inductive kick is wishful thinking, so I've implemented the following circuit:

While a little slow to charge initially, this eliminates pop from DC on on, and inductive kick from off.

Question: Is it an issue if blocking caps are left floating as opposed to discharged when disconnected? In this case, removing a connection at the input doesn't allow the 220uF cap to discharge.

ANOTHER UPDATE: So an upgrade with make-before-break contacts seems to not have solved the issue after all ... the DC seems to be taken care of, but now I have a huge "ON" spike, and I don't understand where it is coming from. Here is the new circuit:

Here is the result at circuit output (beyond transformer secondary) whenever the relay gets switched:

There is a shorting of the transformer primary for a double-digit microsecond duration when switching on, but this wouldn't be the cause, would it? Also there is a much smaller spike when switching "off". Maybe bouncing contacts? Any ideas?


texts: How do I produce a linearly chirp signal in spice?

texts:
I want to produce a chirp signal to test my PLL and found out the lock range.

There is the PWL and pwlFile as Spice commands, but I can't understand how can I produce a linear chirp like this :

This is a Matlab function I have to build such a signal and a binary chirp as well:

fmin = 0.1;
fmax = 1e7 * fmin;
numOfSamples = 5000;

f = linspace(fmin,fmax,numOfSamples);
t = 1 : numOfSamples;

w = 2 * pi * f;
x = sin(w .* t);

plot(x)

binaryChirp = floor(1 + x);
figure,plot(binaryChirp)


texts: Implementing negative feedback on a JFET amplifier

texts:
I have started designing and simulating a simple Jfet amplifier using LTSpice.
The circuit I have below seems fine, apart from too much gain for my needs (about 20x to much gain).

To fix this, I could make a simple voltage divider on the input, but this just seems far to 'hacky' and not a good approach. The best way it seems to me is to create a negative feedback path, thus reducing distortion and also reducing gain.
However my attempts where unsuccessful, this is my first attempt:

This is the result at 'ac_out' off this circuit:

I would guess this is because of the time C4 takes to charge, I try to change the simulation time span to no affect.
I also tryed direct coupling between R5 and R10 but couldn't get that to work.
I know this seems to work fine with BJT's and don't know how I've gone wrong.
My second attempt:

At first glance at 'ac_out' it seemed fine, voltage swing halved as expected, but frequency response became WAY off:

I'm sure I'm missing something, and would greatly appreciate some help and understanding of how to implement negative feedback here, ideally without the use of a AC coupling capacitor.
Thankyou :)


texts: Oftentimes in EE classes we learn about AC analysis and phasors and other stuff heavily based on analog signals. I also know that many digital applications approximate analog signals using PWM. But does everything we learn regarding analog signals still apply to PWM signals? For example, I can see why the integral of a PWM and analog signal would be (almost) the same, but wouldn't the derivatives be drastically different?


texts: I was reading through basic op amp comparator wherein 2 clamping diodes are used. This limits the differential voltage to 0.7V. How does it help?


texts: Does movement along the imaginary axis of a root locus change the natural frequency?

texts:
I have two root locus plots (x-real, y-imaginary) of the same oscillating mode: (1) for a base case system and (2) a system with added feedback. They are so similar, almost identical that I am having a hard time interpreting it but the author comments that "the frequency of the mode has been hardly changed". So he concludes it has not been changed significantly but how can he tell? Is it because the root locus has not moved along the imaginary axis?

On a root locus, zeroes and poles are plotted. What could be changed about these zeroes and poles without changing the frequency of the mode?


texts:
I am a mechanical engineering student and I am working on a research project where we want to use a reverse biased segmented photodiode (OSI SPOT2DMI series) to detect deflections from a high speed laser. We are trying to detect very small variations in the laser signal so there is a large noise signal to deal with. Up until a month ago I had very little knowledge on photodiodes and I have never designed nor built a circuit board before so please forgive me if I am too vague or use the wrong terminology. The design I currently have utilizes four high speed op amps (OPA680 & OPA650). Two OPA680  op amps are used as transimpedance amplifiers for current to voltage conversion of each of the current signals from the segmented photodiode and another 680 is used to generate a sum signal. The OPA650 op amp is used to generate a difference signal which will later be connected to a lock-in amplifier. The laser signal we are studying is around 10MHz so according to the datasheets for each of these op amps they will meet the speed requirements.

My problem is that I don't understand how to connect the power supplies for the op amps. I am going to use a 12v battery for the reverse bias voltage and I would like to use a battery supplied voltage for the op amps instead of a bench top power supply. I am planning on using this prototyping board and soldering on two female BNC pcb mount connectors to extract the sum and difference signals. The OPA 680 requires a +5v and -5v power supply with a max rating of +-6.5Vdc. The OPA650 has a specified operating voltage of +-5V and a max rating of +-5.5V. I don't know much about circuits but I am assuming there is some way you can split a 12Vdc battery supply into +6V and -6V supplies, which would work for the 680, but not the 650. Somebody mentioned to me that I could usse a diode, which usually has a specified voltage drop, to reduce the voltage from the battery, but I am not sure if that will work/how to do that. If there is a way for me to use a 12V battery and split it into +6V and -6V I am also unsure of how I set up my ground bus on the circuit board and how this will affect the bias voltage since the positive terminal of that battery will be connected to the ground. If you would like to see a crude sketch of my circuit I can post it and any help is appreciated!


texts: What are the differences between these PWM controllers, specifically related to driving servos?

texts:
Adafruit has breakouts for 2 different PWM driver:

SPI 24 channel driver based on TLC5947
I2C 16 channel driver based on PCA9685

The specific differences I'm interested in are the ones that would make the former suitable for LEDs and the latter also suitable for servos. The description of the SPI one says "Designed (and ideal) for LED control, this board is not good for driving servos."

What causes that difference? What should I look for in datasheets to understand if I can use a PWM controller to drive servos?


texts: Diode and capacitor part of a circuit: I don't understand it

texts:
I'm fixing an electronic device (a Sony Discman D-50) but there is a part of the circuit that I don't fully understand.
This is the part of the circuit I'm talking about. I've highlighted the part I'm confused about.

There is a 9V DC input from the power supply that goes to a 5V voltage regulator.
There is a diode (D802, the diode component part is 1S2835) with the cathode pin connected to this 9V rail. The anode is connected to the positive pin of a 2.2uF 20V tantalum capacitor.
Now, there is a connection that goes from the junction of the diode and the capacitor to pin 8 of the main IC of this device, which is the Reset pin and expects an input voltage (3.8V).
The problem I'm having is that there is almost no voltage (~0.2V) on this pin so I started troubleshooting the issue, but my problem is that I don't really understand how this diode-capacitor circuit works - and I would like to know.
I've built this small circuit on a breadboard to try to understand it but I still get the same voltage as on the circuit board of this device.
You can find the service manual for this device here in case it is of any help. The schematic I show in the screenshot is on page 26.
What am I missing?


texts: Current issues for Arduino and large 8 segment LED displays

texts:
I am making a clock, using 6 rather large 8 segment blue LED displays. The circuit below is for one of the displays.  All the displays run their grounds through the same N-MOSFET at the bottom right, and this is controlled by an Arduino with PWM to control the display's brightness.

I am running the 12V through the Arduino (via Vin).  I am worried about the current that the displays will be drawing.  I calculated (I am a noob) that I need a 105 ohm current limiting resistor on each of the 3 LED segments in order to get 20mA of current to drive the blue LEDs. If each segment draws 20mA, then an 8 segment display will draw 8x20mA=160mA of current.  And so the clock will draw 6x160mA=960mA of current, if it is at maximum brightness.  Is this correct?

I have a few question:
Is that too much to run through the Arduino?
Is that too much to run through a Cat5 cable?
Would it be better to have a dedicated power supply for the Displays?

Thank you your help,

Fed


texts:
I am trying to input any two of six sensor outputs to a microcontroller that has only two compatible ports.

My first idea was to use two 74hc4051 8:1 MUX IC's but it would require 3+3=6 selection pins.

However, since I am trying to select any two of six, there are 30 possibilities and therefore 5 selection pins should suffice (logically).

Is using two 74hc4051 kind of "in parallel" ok? Is there a way to solve this problem with only using 5 selection pins?

Thank you.


texts: How do I toggle Altium HUD Differential Pair info?

texts: For some reason, my HUD in Altium doesn't show me info of the differential pair that I'm hovering above or when I select it. How is this toggled?


texts:
I am looking to make a pencil whose tip moves to create a waveform as you move it across the paper.In essence, I want to be able to record a sound and then play the sound through the pencil whilst I draw with it, of course, I will use software to lower the frequency to make it more of a waveform and not just a vibration.

I have many ideas but I am thinking of using a solenoid to actuate a pencil which I can move across some paper. Sadly, I do not have access to one to experiment with so I was hoping someone could hook a small solenoid up to an amp and tell me the results before I buy one?

If not this, what is the best way (using an amp) that I could achieve the desired effect? I have considered using a subwoofer but this will be bulky.

I want to keep it simple which is why I am not considering the use of a servo.

Thank you


texts: Digital IC that draws power from data pins

texts:
Just a hypothetical question, are there any digital IC or digital circuit that does not have to have a dedicated power pin, but instead draws DC from data pins (Phantom Power). If there are, what are typical examples?

I'm inclined to think no, but I think my knowledge in digital electronics is very, very lacking.


texts: Timing diagram and performance of Binary Counters

texts:
I have a binary counter which is the following :
https://www.onsemi.com/pdf/datasheet/mc14020b-d.pdf

I want to reset this counter with a signal. I want this signal to be the narrower, ie the length of the pulse to be minimum. But I have to verify that the narrower signal is still took into account by the counter. I imagine that the the length of the pulse cannot be as small as I want. There is a mention about "Reset pulse width" into the datasheet but I do not know if it is that data that I have to consider and if there are other parameters to consider. I do not want to take any risks

-----------------------------------E D I T --------------------------------------
Here is a better binary counters  :
https://www.mouser.fr/datasheet/2/308/1/MC74HC4020A_D-2315492.pdf

The reset pulse width is lower as the reset recovery time compared to the MC14020B but what is strange is that the maximum input rise time is very large ? What does "Maximum input Rise and Fall times" ? Does I have to consider that my pulse needs to be superior to the reset pulse width + the reset recovery time + the rise/fall time ?
Have a nice day :)


texts:
When I travel I take my projects with me. Gotta keep programming and connecting things.

I have a butane iron and it's great for travel, but is there a compact clean way to have a soldering sponge in my bag without risking getting shavings/drippings all over?

I may just put my golden wire scrubby sponge in a baggie, but I wonder if there is something more slick and reusable?


texts: Problem connecting UART Wifi Module to PC

texts:
As refereed to my old question ( Connect UART WiFi module to PC ) which has been solved that days, I have a UART Wifi module ( this one ) and unfortunately I have problem again ! The point is, this time I can't remember what's the last configuration of this module.

What I did this time:

1. Connect Power Source:   Connect modules VCC and GND to 3.3V external power source.

2. Connect USB to Serial ( with TTL Logic ): Connect module's RX to my converter's TX and TX to RX. (in 3.3V mode, you can see the image of my converter in the end of this question and also Before I connect it, I tested it and it works pretty well with my other circuits. ). I didn't connect converter's ground to module's ground

3. Install terminal program: Install Download and Install Eltima Software's Advanced Serial Port Terminal which I tested this module with it before and  it works well.

4. Power up the module and send 3 pluses "+++" after 2 seconds:
I power up the module and send +++ with all possible baud rates as a string (or text file) with Eltima, but I don't get the "+OK" as response from the module.

Other attempts:

1- I tried connecting converter's and module's grounds together and tried again with all possible baud rates but nothing happened.

2- I tried 5v mode of my converter but no luck !

3- I tried connecting nReset and nCTS/MODE/GPIO pins to ground for a while and some other blind attempts but no wish...

BTW, when I start my module one of the lights is blinking and the other is just not blinking but is on.

I think I missed something funny here but I don't know what it is. Please help me find a solution to get this module work. I really messed up with it again!

What can I do to get "+OK" from my module after sending "+++" after 2 seconds as a text file ?

simulate this circuit – Schematic created using CircuitLab


texts:
Is there a way to circuit a power efficient toggle switch controlled by a SINGLE button so that absolutely no current from the power source is drawn at it's OFF state and hopefully but not exactly necessarily, minimal current is drawn on its ON state. So far I got this...

It consumes no power when OFF and when pressed the led turns ON. I couldn't figure out the turning off bit.

Also don't suggest me to use a button that mechanically toggles. I know that exists, but I don't want to use that.

Additionally I do not want to use normally-closed/double-throw buttons and normally-closed/double-throw relays (which means I only allow the normally-open version of these components). If your solution requires those component variants however, I wouldn't mind for you to post them.


texts: Why isn't isolation transformer used in transmission lines?

texts:
I am doing a project "Shock proof socket" by connecting the socket to the secondary of an isolation transformer (230 V). I wouldn't be electrocuted if I touched only the phase wire from the secondary (as the circuit is not completed via ground). If using isolation transformer is safe in this manner, then why it isn't implemented in the transmission lines supplying for household use.

Also what all are the disadvantages of using isolation transformer for this purpose? One reason might be that it needs equal windings in secondary and primary which makes it bulky and costly. Are there any other reasons?


texts:
I am currently building an audio guitar pedal. I was suggested to use an external clock as reference for my CODEC and MCU. I've been reading the "Oscillator design guide for STM8AF/AL/S, STM32 MCUs and MPUs" application note for a while now. I am trying to understand which oscillator best fits my MCU, however I am not able to find a good external clock that matches the requirements they pose in the guide.
I am mostly looking for a HSE of about 25 MHz, since I am working with audio.
I would appreciate it if I could get some recommendations for external clocks that would work for my project.
In terms of the capacitor values I can use the guide to figure that out.
Thank you in advance,


texts:
I thought I got familiar with noise calculations and RMS nv/rthz conversions, hence I went forward to test my understanding.
I am comparing some opamps based on their noise levels.
So I wanted peak to peak noise, for an opamp ADA4528 at 0.1 to 10 Hz band, and they quoted the same in datasheet as 99 nVpp. so I wanted to verify this and I went on to their noise density graph at page 18. which shows noise density to be 6nV/rtHz. at 0.1 to 10 Hz and its nice rectangle so I went on and multiplied 6 nV/rtHz with sqrt(9.9 Hz) to get 18nVrms. so to get output noise I multiplied it with gain (100) and everything shattered. :P
Where am I going wrong. in datasheet it says 99nvpp at gain of 100 and I get nowhere near it by calculation.
Please help.


texts:
I was wondering how does some Bluetooth radio chipsets achieve the dual mode (BR/EDR + LE) ? How do they manage to distinguish between two frames of different modes?

Any help or document explaning this will be precious to me.

Thank you !


texts: Calculate exact timer frequency for ATTiny

texts:
Trying to wrap my head around these overflow timers for the ATTinyx5 (45 in this particular case). I seemed to have a great handle on it with the ATMega328 but I cannot get it to work the way I want on the tiny chips.

I'm trying to achieve a 1 second pulse (for the purposes of testing, LED on for 1s then off for 1s). I know there are many ways to achieve this, but the simplest seem to be by utilizing the overflow ISR.  Here's what I've got so far:

//Who can ever remember what the prescaler combinations are?
//These are for Timer0
#define PRESCALE0_1 _BV(CS00)
#define PRESCALE0_8 _BV(CS01)
#define PRESCALE0_64 (_BV(CS00) | _BV(CS01))
#define PRESCALE0_256 _BV(CS02)
#define PRESCALE0_1024 (_BV(CS02) | _BV(CS00))

void setup()
{
  DDRB |= _BV(PINB0); // Set Pin 5 (PB0) as output;
  PORTB &= ~_BV(PINB0); //Set it to low, just to be safe

  cli();
  TIMSK |= _BV(TOIE0);
  TCCR0B |= PRESCALE0_64;
  sei();

}

uint8_t _interval = 2;
uint16_t _pulseCount = 0;
uint16_t _pulseMax = 15625; // = 1s / 0.000064s
bool state = false;

ISR(TIM0_OVF_vect)
{
  _pulseCount++;
  if(_pulseCount >= _pulseMax)
  {
    _pulseCount = 0;

    if(!state)
    {
      PORTB |= _BV(PINB0);
      state = true;
    }
    else
    {
      PORTB &= ~_BV(PINB0);
      state = false;
    }
  }
}

As you can see, I'm doing little more than enabling the Timer0 overflow ISR and setting the prescaler to 8. Now, I'm running the chip at 1Mhz by setting the /8 clock fuse.

Given that 1 / (F_CPU / 64) = 0.000064 or 64 uS that should mean that 1/0.000064 = 15625 overflows per second. So, the general plan was to count overflows in a uint16_t variable util it reached 15625 and then do what I needed to do at 1 second. Sort of an overflow for the overflow.

But instead, I get a pulse every couple of minutes!. To get the pulse I need I have to set _pulseMax to more like 128 which should be 0.000064s * 128 = ~8ms.

I'm sure whatever I'm doing is terribly stupid, but I can't see it. What am I doing wrong here?


texts: Do carbon resistors not follow tolerance as they age?

texts:
I'm trying to figure out the problem with my LCD and resistors.
The micro I'm using is AT89S52 and the LCD is a standard display based on the HD44780 chipset.

Part of the code in my micro allows for the output lines P1.0 and P1.1 to be configured in any combination so I tested all combinations and noticed only two things. One contrast setting, and completely blank display.

The completely blank display is normal with P1.0 and P1.1 being high. But it seems all other combinations return the exact same brightness intensity even though the resistor values are different.

The only thing I could possibly contribute the problem to is the age of some resistors. At a local shop, the resistors are probably 40+ years old because sometimes when I look at them the leads are not shiny silver. They're dull-ish silver and the markings are not vivid and bending them is not super easy. The resistors I order online seem brand new: shiny leads, vivid markings, nicely coloured, etc. In all cases, the resistors are carbon film with 5% tolerance according to the markings.

Does age make the resistor value out of spec?

Also, My tests were done with a regulated 5.5V power (brand new 9V battery passing through a LM2940 regulator).

The reason why I use this setup is because I want to enable the dark setting (P1.0 and P1.1 = low) when the battery is almost dying (circuit voltage under 4.2V) and when the battery is brand new (circuit voltage at 5.5V), I want to enable only the light setting (P1.1 = low and P1.0 = high) and when the battery is sort-of new then I want the medium setting (P1.0 = low and P1.1 = high)

So does resistor age cause my problem, or are the values of my resistors not optimal? and is 5% carbon OK? or must I use 1% metal film?


texts: will a 48V DC motor work with a 36V Battery and controller

texts: I have 1000W / 48V ebike motor. I have a 36V battery and 1000 W controller from another ebike. Could I use the 36V battery and controller with the 48V motor?


texts:
This is the schematic of a (log) Opamp amplifier. The objective is to calculate the V_out.

simulate this circuit – Schematic created using CircuitLab

To solve this figure I can apply the formula for log (op)amplifier i.e. $$ V_{out}= -V_T\space ln(\frac{V_{in}}{I_S\space R_1}) $$

The temperature is not given. The npn transistor material is Si and op-amp is IDEAL.

$$ \text{How do you solve this circuit for } V_{out} \text{ without using the formula }$$

UPDATE

The circuit simulation( with circuitLAB) gives

    V_out =  -15volt

It seems, that in simulation, the transistor is being treated as an Open Switch. Should it be ?


texts: Decrease Impedance at Higher Frequencies

texts:
I am trying to see if I understand how impedance works correctly before I build this into a real circuit. Basically I have an inductor (helmholtz coil) driven by a function generator, now by itself we know the higher the freq goes the lower the current the coil will receive. If my understanding is correct, I can put a capacitor in parallel with the coil, which would mean at higher frequencies the Xc would decrease and Xl would increase, but since they are in parallel Xtot should decrease, thus as a result you will get a higher current at the same frequency than if we had just had a inductor (coil) in the circuit by itself. Is this understanding correct? Or is there a smarter way to increase the current my circuit receives at a higher frequency, besides increasing the current outputed by the generator/changing the coil design itself.

p.s. this is a re-expression of the question asked here Impedance for Helmholtz Coil Connected to Audio Amplifier but in a more detailed and precise way I hope


texts: Why is the Current Voltage Curve for the Foward Bias of a Silicon Diode an Exponential Curve

texts:
Using Circuit Wizard 3 I tested the forward bias of a 1N4001 diode. This is the circuit I used:

and this is the graph I got when I plotted current through the ammeter against voltage across the diode.

Why is it that the current voltage graph gives an exponential curve?


texts: Attiny88 as I2C gpio expander - analogRead and digitalRead functions do not work

texts:
I am working on making a system that has two PCBs mounted atleast 30 cm apart (but not more that 50 cm). The first PCB is the master and the second is the slave, both these have analog and digital IOs. I decided to use an UNO as the master and an ATTINY88 as the slave, and programmed the ATTINY88 as a GPIO, using I2C. I am using this library to connect to the ATTINY (using I2C) and either write (analog or digital) and read (analog or digital) from various sensors (NTCs, Hall sensors, LEDs or control a DC Motor). I tested this on a breadboard style setup without any issue. I implemented this on a PCB and the analogRead, digitalRead functions dont seem to work. The output is always 0 at the master's serial print. I was wondering if it could be the length of the cable (it is around 35 cm) connecting the master and the slave. It seemed odd to me that I can set pins on the ATTINY using the UNO but never read from it. I tested the breadboard application for almost a month before I got into implementing it on a PCB, and I never found this issue.
I sat in the corner to brainstorm, and came up with a few reasons (I could be totally wrong..):

The only difference between the breadboard test setup and the PCB was the length of the cables, maybe the overall I2C bus capacitance is too high?

How can I check the practical capacitance?

Continuing first point: pull-up resistor values are wrong, and is causing some issue(?)

If there was an issue with the capacitance, shouldn't the whole system not work, and why is only the write functions working?
Would be amazing if anyone can help me out.
Thanks in advance!


texts:
I am trying to build a circuit which converts 6V DC to 5V DC. I have simulated the circuit using multisim and have achieve a "fairly" stable output of 5V.
However, when I tried to measure the output voltage from the opamp (LM741) it oscillates around ~0.1mV to 9V (measured at probe5).
The datasheet for the IRF5305 says the gate threshold voltage is 2V to 4V,.
Is there anyway to stabilize the output voltage from my opamp to the MOSFET?


texts:
My DAC gives  +/- 16V analog output voltage and +/- 20mA output current.

Output impedance in voltage mode: 25 miliohm.
Output impedance in current mode: 100 megaohm.

I need to design an attenuator for 100 microvolt steps and a signal range of 500mV output.
Voltage range given is +5V  to -5V.
This has to be done from differential ended as well as single ended output from DAC.


texts: Why is there an inductor sort of a thing inside this antenna?

texts: I have a 20cm antenna exactly of the same shape as shown in figure. I want to know why is there a inductor sort of a shape in its monopole? What is its purpose? Does it affects its designed frequency? Or it has to do something with its gain or impedance matching....?


texts: Formula for Logarithmic (audio taper) pot

texts:
What I would like

I am trying to determine the formula for an audio taper (logarithmic) pot.

I would like a formula that takes R and P as inputs. R being the total resistance and P being the "percent on", i.e., in set [0, 100], and yields the resistance between the middle terminal and one of the outside terminals.

Can someone provide a purely mathematical answer, not a lookup table or anything.

Back story

I am trying to plot frequency ranges for a 555 timing chip in astable mode.

Again, I am looking for the formula, not how to plot it or a look up chart. Just math! :)

Additional thoughts...

I have been thinking that this may be it. I am looking for what number raised to 10 (the number of degrees I want) will equal my total resistance.

If I want to find the resistances at 10% intervals, the formula would be:

X^10 = R, solve for x: 10th root of R ... meaning that ...

The resistance at 40% would be (10th root of R)^4, can someone confirm this?

--- Update: I tested the above formula and it kind of looks like the graph...


texts: Relay: higher voltage allowed at lower current?

texts:
Is it safe to use a 30VDC/1A relay for a voltage of 60V but a current of <100uA?
E.g. this one:
http://www.mouser.com/ds/2/315/mech_eng_gq-1075992.pdf


texts: SPI Interfacing using Serial Port or USB

texts: I have a nRF24L01+ module from Nordic Semiconductors. It has SPI interface. My laptop has USB ports and I have a Serial Port (Using a USB-to-Serial_Port adapter). What is the best possible solution to interface with the SPI module?


texts: What effect do different SMT stencil materials have on results?

texts:
I have a PCB with 20-mil pitch SMT pads for a QFP-64. I ordered a stencil for it, which is made of some flexible material. I haven't had much luck with it, I suspect because the material is so finicky. I keep getting big globs of paste along the entire side of the package, instead of on each pad. I also find that their recommended setup time for a single board using this flexible stencil is prohibitive, to the point that I'd be better off using my present method of a pneumatic solder paste dispenser and a microscope.

I'm thinking of trying again with a stainless steel stencil. Is this likely to improve precision and production time?


texts: Wave Impedance vs Characteristic Impedance

texts: What is the physical difference between Wave Impedance and Characteristic Impedance? What are the meanings of these in a wave port in a simulator software?


texts: Why does this two NOT circuit oscillate?

texts:
I built the following circuit and it oscillates at about 1 Hz. I can't figure out however how it works. I picked the design up from an old Bernard Babani book (1979) on 7400 series ICs. The book doesn't explain how it works either. The book uses a 7400 to supply the NOT gates (combining two NAND gate inputs to form a NOT gate). I don't do that, instead I have a transitor based circuit that behaves as a NOT gate. However it oscillates as the book suggested it would. I implemented the circuit in circuitlab and I can get the simulation to show square wave oscillations, see below.

Simulation from circuitlab


texts: Amplifier does not sound right when balance is centered

texts:
I have an HK 590i amplifier.   When the balance is centered sound is like coming from far away (voices).  Sound is good only when balance is full left or right.
I researched the site and found this answer that seems related to my problem Stereo heaphone doesn't work properly when the balance is centered .   I have the amplifier schematic.   I would like recommendation about where to look for the problem (broken earth connection I think).


texts: How to measure resistance with a multimeter?

texts: This may be a very simple question. In my lab guide (I am a freshman Electronic Engineering student), we are supposed to build and analyze a circuit on a breadboard. First, we need to select some resistors for our circuit. The lab guide says: "To measure the resistors, set the multimeter to voltage mode". I am confused. Aren't we supposed to set it to resistance mode (with an ohm sign)?


texts:
For the pictures above, I am confused as how to how they got/derived the formulas for the peak to peak ripple voltage (VrPP) and Vdc. So far, I got the output voltage, which is 14.9 volts. However, I am also confused with that VrPP and Vdc mean as well.

Another question: How exactly do the ripples occur, and what would happen if there wasn't the resistor (RL), or a resistor when there's a capacitor?


texts: What I'm asking about is if it's possible to discharge one side of a capacitor.  I've found a question about that, but I also found the answers to be a little unclear or questionable.  I imagine that if you were to do so, you would need to put energy into it, because you would be removing charge from one side of the capacitor and creating electrical potential energy.  Could this be done if you connected the positive and negative ends of a battery to a negative and a positive side of two capacitors?  Could doing that cause capacitors to break down?


texts: Why won't this 555 timer flashing circuit work?

texts:
The circuit which I made shows the following behavior, when power is given to the circuit:

Sometimes it lights up, sometimes it doesn't.
When it does light up, it flashes properly for a few seconds but then becomes dimmer and dimmer.

What is causing this unpredictable behavior? Is it the components? Or is it the breadboard?

This is my first project using an IC

Yellow wire shorts 4 and 8. Orange wire shorts 2 and 6

UPDATE: The circuit is now working. All I had to do was change the battery!

Circuit diagram from a YouTube video where I got the circuit:

555 pins 1, 2, 3 and 4:

555 pins 5, 6, 7 and 8:


texts: Many-pins & still-simple IC, how to prototype with it?

texts:
I'm building my second project, it will use TI TVP5146 video decoder, which has 80-pins, and TI Tiva C. What prototyping accessories will I need? I think it can be clearly stated what such many-pins & still-simple IC needs. I must avoid re-ordering because of very low budget. Please, help me resolve this without blind orders.

Will I need large breadboard, or PCB-like board? The project has to handle multiple video inputs: SCART, composite, S-Video. How to connect those cables to the prototyping-board, how to resolve input pin's different roles depending on cable being used? I could need some prototyping-board just for the cables? Maybe it can be predicted what commonly used registers and capacitors will be needed, or maybe there's a source to find some reference on this?


texts:
Could someone point me towards a level shifter IC or circuit that can handle 10-30v to 3.3v shifting? It doesn't need to be fast or bidirectional just want to data log the state of some 12v and 24v switches. Trying to build a data-logging device with a 3.3v ESP32 micro-controller.

I've been scouring Google for a level shifter that can handle a voltage range for input but I've not been able to find one yet.

Any help would be appreciated. I've been stuck on this for a few weeks.


texts: To see an encoded AM radio wave, what kind of Oscilloscope do I need?

texts:
I want to see an AM carrier wave and the resulting encoded frequency and the DC (I think) out of the wave, the information getting to my earpiece.

What kind of Oscilloscope do I use for seeing the representation of radio waves?  Do I need an analog or will digital work?

I have seen videos of digital, but they appear to be "slow," on the older Analog scopes, it is faster and seems more responsive.  I'm not sure I care which one as long as it is not a struggle to see it.  With digital, I am guessing I can capture the information and view it offline, which would be better for analysis, so I can understand.

For frequency, I mean a USA AM radio station, 535 - 1605kHz.

I'm sure after that I'd want to use it for non-RF things.

One thing I am interested in is a Crystal Radio, no battery, and a scope showing what is being received, if that is even possible.

I am not asking for a specific product recommendation.

I originally asked this, but I think I didn't ask the right question:

Can a USB Oscilloscope be used reliably and accurately for RF projects?


texts:
I'm trying to build a simple voltage comparator using LM324N. Here is the circuit:

simulate this circuit – Schematic created using CircuitLab
The strange thing that happens is that after apply the input voltage, a small part of it gets clipped off. Here are the pictures of the circuit and the resulted voltages:

I've connected all of the grounds and negative terminals (i.e., CH1, CH2 and the negative terminals of the input voltage and power supply) together. Also using another LM324N and applying input voltage with a resistor didn't solve the problem. As soon as I disconnect the input voltage from LM324N, it gets back to its normal shape which is a sine wave with 3V amplitude.
How do I stop the voltage from clipping on the opamp input?


texts: Do standard white LEDs produce a full spectrum of light?

texts:
At places like Radioshack, small (and sometimes large) LEDs are available that are labeled to be "white". This is a link to a Radioshack page for such an LED: http://www.radioshack.com/5mm-white-led/2760320.html#q=white%2Bled&start=2

Does a light like this produce a full spectrum of light, such that appropriate light filters could produce any spectrum of visible light?


texts: Is there a way to average resistors together to get a tighter overall resistance tolerance?

texts:
I have a very sensitive, kHz frequency level, application where I need two matched resistors of the same resistance better than 0.05%. Like maybe by one magnitude (0.005%).
I am basically needing to match two resistors together so as to form a differential bridge in order to measure a specific resistor. 50 kHz 180 degrees signal → 75 ohm → Resistor ← 75 ohm ← 50 kHz 0 degrees signal
Here is the schematic:

I need the 75 ohms to match so the signals across the 10 ohm resistor are symmetric in magnitude.
I can buy two 75-ohm 0.05% resistors, but, to get a lower tolerance than that, is there a way to make a circuit that uses a whole slew of 0.05% resistors and then averages them together to get better performance?


texts: Eagle PCB design how to make flat pins for the power socket

texts:
All the Eagle libraries I have found have round small holes (like for the THT resistors or capacitors). But most of the available ones have flat pins (like this one):

My question is: How to create this shape hole? Any advice appreciated.


texts:
I am currently working on a device that is to be used in hostile environments. It needs to be explosion proof. Our team has decided to place our instrument in this housing shown here.

http://www.adalet.com/xdhl-4-id-instrument-enclosure

Now the problem is we have to have the wiring out of that casing. For that there is a blue cap at the top, which can be pulled out and wires can be passed through it.

After wiring is done, we need to fill it with something to contain the explosion.

Anyone has any idea how to make the wiring explosion proof? What wiring to use? What material should the hole be filled with?


texts: In a transformer power is conserved and p=vi. So, in a step up transformer, if secondary voltage is increased the secondary current has to decrease. Now, my question is, if the secondary winding in connected to a constant load, v=ir rule implies, if secondary voltage is increased the secondary current has to increase. These two sentences contradict each other.


texts: Why does a turbine with PMSG and full converter system draws reactive power when turbine is stopped or there is no wind?

texts: Our turbine has a permanent magnet synchronous generator and full converter system (rectifier diods for rectification and IGBTs for chopping dc link voltage and as inverters) which means its generator doesnt need excitation current to start. Then why does it draw reactive power whenever turbine is in stop mode due to no wind or if it is manually stopped? What is purpose of this reactive power? I have been searching for this for over a month now but could not find any answer.


texts:
I'm using a FT230X UART, and I'd like to use it with a non-standard baud rate. I came accross this note, explaining that I have to modify the driver file, but even with this documentation I have some trouble.

I'd like to replace the standard rate of 115200 baud with a non-standard one of 125000. I tried to follow the method described in the note but I'm not going anywhere whis this at the moment. Could anyone explain how to do it?


texts:
I'm new to verilog.

I'm trying to implement a 2:1 multiplexer on a FPGA development board (DE1-SOC altera) using built in switches and LEDs.

The following are the assignments that I'm using for the multiplexer, these pins are connected from the FPGA to the switches and leds on the dev board:

I'm getting this error on output LEDR[0];

  declaring module ports or function arguments with unpacked array types
  requires SystemVerilog extensions

I've googled unpacked v packed arrays but I cannot understand what is the issue, I just want to set this pin as an output.

SW[0] - select
SW[1] - input 1
SW[2] - input 2
LEDR[0] - output

This is the verilog

module ligths (SW[0], SW[1], SW[2], LEDR[0]);

input SW[0], SW[1], SW[2];

output LEDR[0];

assign LEDR[0] = ((SW[2] & SW[0]) | (SW[1] & ~SW[0]));

endmodule


texts: How to Design with an AC Motor for a Specific Acceleration Objective

texts:
How do I determine the power necessary to accelerate a pump to meet a specific change in demand?

The design is a VFD driving a constant torque positive displacement pump with a varying capacity load.  The VFD will control pump speed thus met the flow demand.  The steady state power is easily addressed.  I need to assure that I can accelerate the pump from 50% load to 75% load in one second.

What are the specification parameters that will address this?  I have talked with the suppliers of each of the components and none have a formula or procedure to determine this.

After determining this necessary properties, I need to include the these parameters into a dynamic model of the plant in Matlab.

I also need to determine how to bring the pump down in speed from 100% to 0% as fast as practical and know how fast that is.  The load rejection does not occur often so regenerative braking is not necessary, a resistor is expected to be used.

I have looked at this from a dimension analysis view but I can't seem to find what the appropriate relationships are.


texts: What is the minimum distance that BLE 4.0 capable device be programmed for..?

texts: After Searching on Web found out that the range/Distance of BLE device transmission can be controlled by varying its transmission power and frequency. But could not get how specific can we bet on the minimum distance covered by reducing the transmission power of a BLE capable device to the lowest.


texts: Ideal Energy/Battery Source for a Battery Powered Lamppost

texts:
Hello everyone,
Relatively new to electrical engineering (my background is more in coding), so, thank you ahead of time for all your help!

Project:

I was tasked with creating an outdoor lamppost for an event at a campground (IE: no immediate electricity source). At first, it seemed quite simple, but, looking at the necessary requirements, it seems to be more complex than I thought.

Requirements:

I need to find a way to power a high-powered LED light bulb (ideally 12W equivalent) for 10 hours a day (for 3-4 nights - for a total of 30-40 hours) without immediate access to an electrical outlet. So, if I were to use my currently provided 12V, 12W bulb, it would be around 120 watt hours a day.

This battery source needs to be able to be outdoors, and face rain/weather. There may be a tarp, tent to cover it.

I may have access to a generator to recharge my battery source at another location if need be.

I currently have a bright DC 12V light bulb that would be ideal for this project, but, I could also use a AC light bulb if need be.

Potential Solutions:

Connected 6V Lantern Batteries:

Connecting multiple lantern batteries together, and swapping them out on a daily basis. Walmart has a set of Rayovac Heavy-Duty Lantern Batteries for around $2.50 each. Each one of these batteries has around 5 ah (not the highest quality, but, they are cheap!)

Pros:

Connecting these batteries in parallel and series would give me the
20 ah, and 12v specs needed.
It would come out to around $15 a day.
Would be easy to put in a large water-proof container and connect to
the lamppost

Cons:

Bit wasteful - I'd burn through around 20 of these batteries, and
would have to recycle/dispose of them
Sealed? - Unsure if I could put them in a waterproof container. Do
they need venting?
Mid-range cost: Would come out to around $50-60 due to the number of
batteries needed

12V Deep-Cycle 20Ah+ Battery:

A simple 20ah+ deep-cycle battery would provide me the DC power needed on a daily basis. I would then detach it during the day, and bring it to the generator to charge.

Pro:

Cost - Relatively cheap, at around $50, this battery option would be
affordable
Set it and Forget It - No need to connect multiple batteries
together. This would just be an easy wiring job.

Con:

Venting - Unsure if I could place this in a simple waterproof
container outside. Does it need to vent? Or, would a AGM deep-cycle
battery be ok in a vent-free container?
Recharging - Unlike the lantern batteries, I would need to bring this
to a generator on a daily basis to recharge. Not the end of the world
though.

Ideas:

I am vacillating between both options. Ideally I would like to go with the deep-cycle battery, but I am quite concerned with the venting problem. I don't believe the 6V batteries need to vent, so they could be placed in a simple container.

Question(s):

Does one of these solutions stand out more to you as the better fit?
Are there other battery solutions that you think would work better?
Do I need to use a deep-cycle battery, or would something like this
battery work?

Again, thank you ahead of time for any guidance you could provide!


texts: Determining acceptable single-pulse heating in a wire coil

texts:
I'm trying to determine the max heating allowable in an insulated copper inductor. This is a pulsed application where peak current in the 5kA range is delivered over <1ms. My task is to figure out how much higher we can go (theoretically) above 5kA without things blowing up / melting.
The fusing current of, say, #8 copper is 14kA over 32ms, which is an order of magnitude more time than this design's pulse length. (We are only considering a single pulse right now, i.e., assume full cooling to ambient between each pulse.)
Based on that, it seems like fusing current should not be the limiting factor. So would the limiting factor be? The melting point of the insulation around the wire? Standard insulation is ok up to ~100degC...but my intuition says that raising the temperature of my inductor say, 50degC in 300 microseconds would still cause something to go very wrong very fast. Or maybe not! I'd appreciate help thinking this through, I'm not an EE! What factors should I be thinking about when heating at this fast a ∆T, if not the insulation melting point?
At the moment, we're thinking about this without regard to cost - an exotic insulation material might be ok if that solves problems.
(as a note: this is only a back of the envelope calculation to explore the design space - if we were actually going to build this, someone who knows what they're doing would be on board!)


texts: Component ratings for sensing AC with microcontroler

texts:
I am working on a project where a part of the circuit I have to design is sensing AC with microcontroller. As you can see below this cicruit is meant to operate with resistors, capacitors and an optocoupler.

Here are two designs I have in mind:

This circuit has to be reliable and last for a good amount of time (at least 5 years).
The circuit will run only when the window shutter is moving which means the circuit will be mainly off.

In case I chose first design (preffered because of size limitations) I would use X class capacitor. Final value is yet to be determined.

The most problems I have is with the resistor. When the circuit turns ON / when AC (230 effective, 325 peak) voltage becomes present in the circuit, the current will only be limited by the resistors resistance before capacitors imedance kicks in. This means that the voltage across resistor will approximately be:

where worst case scenario AC ampliude is 325V (or more because of other factors) and Uf (diode forward voltage) will be 1.1V +/- 0.4V.

This means that for a brief moment power dissipated by the resistor will be more than 10.5W. I know that some resistors have graphs showing pulse powers. Should I even take this into account in my example?
I don't really know how long this pulse will last since I don't know how to simulate this, but I really think we are talking milliseconds or even less. Can anyone help me with this problem?
Would second circuit be more reliable than the first one? The heat sholdn't really be an issue since the sensing part of the circuit (which I'm showing here) isn't really supposed to work for long periods of time. Not even in minutes range. But like I said the 1st design is the one I would prefer.

Some additional info:
I've looked over several resistor types. I read MELF resistors are usually good to use where pulses are likely to occur though I would rather use thick film smd resistors which are easier to mount.
Resistor will be rated for 400V+ and after the capacitors impedance kicks in the power dissipated by the resistor will be aroun 1W which is quite some power but like I mentioned previously won't be lasting for a long time (I was hoping 1.5W resistor would do the job).

The optocoupler is probably going to be the one shown in the design. Optocouplers absolute maximum ratings: If = +/- 50mA, Ifsm = +/- 1A, I will try to stay in < 10mA range.

Generator frekuency does no reflect actual frequency the circuit will be exposed to. AC mains voltage: 230 effective / 325V peak, frequency: 50Hz


texts:
I have an analog accelerometer I want to sample at 100HZ, I also want to plot the data with time of each sample so I have acceleration over time. To keep track of time I was going to use millis(). To sample at 100HZ I can use a timer, but AnalogRead() has overhead and I was wondering how to sample at 100HZ correcting for the overhead of AnalogRead()???

Also sending data over serial has overhead, not sure how to compensate for this, I want to get acceleration over time plot that is at least somewhat accurate if possible. I dont have the money right now for a RTC chip


texts: What are these holes for inside a plastic junction box and how to use them?

texts:
I would like to mount a Raspberry pi case inside this box I bought and make it possible to remove it.

I designed and 3D printed this part to fit on the holes and I would hotglue the Pi case on the other side. But the part does not fit well because it's hard to fit a caliper inside the box and measure the exact placement of the holes.

How can I know the exact placement/dimensions of these holes?
Are these holes placed in a common pattern and is the placement of these holes usually the same relative to the known inner dimensions of the box?
How are you supposed to use them?
What are these holes called?


texts:
I want to make a very simple oscillator that produces the sound of telephone ringing (I want to make a ringer).

I will not connect it to a telephone so the quality of the sound is not important. I will connect it to a 8-ohm speaker, just for learning. That's why I wanted the circuit to be easy.

I looked at the circuit of my telephone. I didn't understand it because it has many capacitors and resistors, and it has these transistors:

S8550 D 148

S8050 D 113

2N 5551 148

2N 5401 148

S9014 D 113


texts:
I have the led driver of Adafruit connected to my atmega32. I adjusted their library for the Arduino, so now I just need a µcontroller and not an Arduino. This thing works.

Now I want to control the brightness of the leds with a BH1750FVI.
I use the I2C library of Peter Fleury, library download link. Then I added some code so I can get values out of the sensor and adjust the brigtness of my leds and here things go wrong.

I initialize the I2C, then I send to the sensor to wake up, give me a measurement at High resolution of 1Lx and go back to sleep. Normally this should work but nothing happens to my leds, even my blinking leds (not dependent on the measurement of the sensor) doesn't work.

Because the sensor works on 3.3V and my atmega32 works on 5V, I use a jy-mcu logic level controller.

What am I doing wrong or is it maybe my jy-mcu logic level controller?

my code:

#include <stdlib.h>
#include <avr/io.h>
#include <util/delay.h>
#include <compat/twi.h>
#include <math.h>
#include "i2cmaster.h"

#define adres 0x23

/** Calculate from the sensor values to the pwm levels for the leds */
int calcLight(unsigned char lightData){
    int lData = (int) lightData;
    if(lData == 0){
        return 0;
    }else{
        int calcData = round(lData / 655.35);
        calcData = round(calcData * 40.95);

        return calcData;
    }
}

unsigned char getData(){
    unsigned char data = 0x0000;

    if(i2c_start(adres + I2C_WRITE)){           // set device address and write mode
        i2c_stop();                             /* failed to issue start condition, possibly no device found */

        return 0x0000;                          // deactivate all 8 LEDs to show error */
    }else{
        i2c_write(0x01);
        i2c_stop();

        i2c_start_wait(adres + I2C_WRITE);  // set device address and write mode
        i2c_write(0x10);

        if(i2c_rep_start(adres + I2C_READ)){        // set device address and read mode
            i2c_stop();

            return 0x0000;
        }else{
            data = i2c_readAck() << 8;              // read MSB
            data = data + i2c_readNak();            // read and shift LSB
            i2c_stop();

            return data;
        }
    }
}

int main(){
    int lightData = 100;
    unsigned char data = 0x0000;

    tlc5947(2);
    begin();
    i2c_init();

    ledsOff();
    write();
    _delay_ms(5000);

    while(1){
        data = getData();
        if(data != 0x0000){
            lightData = calcLight(data);
        }

        if(lightData <= 100){
            setPWM(4, 100);
        }else{
            setPWM(4, lightData);
        }

        setPWM(19, 2000); // control blinking led
        setPWM(28, 2000); // control blinking led
        write();
        _delay_ms(5000);
        ledsOff();
        write();
        _delay_ms(5000);
    }
}

Thanks in advance

PS.: I'm new to I2C.


texts: Clock generator is not oscillating on the given XTAL's frequency

texts:
I created a PCB which needs to have a solid and precious clock source.
For this purpose I used a Dual Inverter with Schmitt trigger (NC7WZ14).

Now CLKI seems to generate 66kHz square signals (measured by an oscilloscope at the point of CLKI).

Why is this circuit not generating 11.0592MHz for me?

EDIT:

Referenced from: https://www.electronics-tutorials.ws/oscillator/crystal.html, at section "CMOS Crystal Oscillator".

Thanks.


texts: Why does it hase a power supply for the rs232 to rs422?

texts: We have a anemometer with RS422/485 communication, and we would like to connect to the PC, but we have only RS232 so I would like to purchase a converter, but some converter has an external power supply, some not. The maximum distance will be less than 100m. I which case do I need an RS422/485-RS232 converter with external power supply?


texts: I've been trying to get this question done for a couple of days now and no matter how much I try I've been unable to get it done. Your help in this question is greatly appreciated.


texts:
I bought two fans for my PC case, but I accidentally ordered the 5V version of the fans. The box states that CAN'T be run on 12v of regular Motherboards or the'll die.

I happen to have a step-down voltage converter that can handle 12v and I can regulate it to 5v. So, with a little soldering I can solve my problem. My doubt is about that the fans are PWM and I intend to preserve that functionality.

I thought of connecting the +12 and GND to the buck converter and the PWM and TACH directly to the motherboard. I'm almost certain that it's OK to do it, but I want to be a 100% confident. I'm not sure if the TACH and PWM from a regular motherboard will have higher voltages than this fans actually supports.

Am I safe doing this?

PS: If you're wondering why I don't return the fans the answer is: Argentina.. shipping and custom taxes are more expensive than the fans itself and I bought the fans overseas..


texts:
So I've found a motor circuit which looks like this:

Since many users here believe that my hand-drawn circuit schematics are in fact pictures of flying spaghetti monster, I'll also provide a written description:

There are two input lines marked + and - going to the motor. There is a capacitor connected in parallel with the motor. There is one capacitor connected to the positive side of the motor and the motor's metallic body and there is one capacitor connected to the negative side of the motor and the motor's metallic body. The capacitors look like multilayer ceramic capacitors and have capacitance of \$0.1 \mbox{ } \mu F\$. The motor is a Kysan Electronics FK-180SH-3240 DC motor. It is also worth noting that the motors have nominal voltage of 3 V, but are powered by a 2 cell LiPo battery and are controlled by a microcontroller-based circuit.

So my question is: Why use 3 capacitors, with two being connected to the motor body? It would seem logical to have capacitors on motor terminals to keep interference away from the microcontroller, but I don't see how having capacitors soldered to the motor body would help.


texts:
I need some hints in designing a ±300 V amplifier stage. The output stage should be two MOSFETs. The current needs to be very low for now (about 50 mA). The bandwidth is not so important for now.
The problem with this is that I cannot apply any standard circuit like a discrete operational amplifier because of the voltage and it is hard to get good BJTs for that voltage range to drive the complementary MOSFETs.
What I want to achieve is a gain of 40, to be able to control the output voltage with a generated input voltage from a controller. Do you have any literature hints for me especially for high voltage amplifiers?
Now I simulated some very basic operational amplifiers. This is a very simple one with resistors as current source but it works in the DC simulation. It is not fast at all. The downside is that there is a lot of offset which must be corrected at the input of X5. The voltage range is also limited because the choice of transistors requires these low voltages. Maybe I could scale that up to 200V for each rail. What do you think? Is this a design to refine for a very simple voltage source or are there design issues one can't solve in a real world application?


texts:
I have a linear regulator in a product which works from 20 to 240VAC: a two stage linear regulator. Stage 1 converts to 18V and stage 2 to 5V. Stage 1 starts heating up as the input voltage increases to 240V. The load on 5 V is about 10mA.

How can I reduce the heating at stage 1?