texts: A question about Automotive failsafe IC ATA6842

texts:
I am a student of Vehicle engineering.
I had read a datasheet of a automotive failsafe IC:ATA6842 and I don't know what it is.
Please have a look at P4 of the datasheet.

I know what in the red frame is a low side MOS BDC control circuit and a current differential amplification circuit.

But what I don't know is,what is the use of the circuit in the blue frame?
What happene to the BDC motor with this circus?


texts: I'm trying to fix an old (1929?) AC, 60 Hz fan motor.  None of what I've found is this simple (or old). It needs the stator rewound. It has only 4 posts and I'm copying the orginal windings. I could not tell from the old winding if the poles alternate polarity. Physically, I'm winding them all clockwise but can alternate, if need be, by connecting adjacent coils head-to-head & tail-to-tail. Right hand rule would reverse the N-pole. I presume the 60 Hz house current provides the modulation to actually make the motor spin. I've attached a photo.


texts: Matlab low pass filter design -removing noise

texts:
I am designing a low pass filter in matlab to remove the noises shown in the image. The original signal of interest lasts only for about 80 ms and rest of the signal are noises from probe tip.

In matlab, i used the following script.
d=fdesign.lowpass('Fp,Fst,Ap,Ast',0.001,0.5,60,1);

But I not getting the effect of removing the noisy signal exactly. I dont understand the parameters 'Fp,Fst,Ap,Ast'. I tried playing with those values, But its not working. What values should i give to these parameters to remove the noise exactly and have only the signal of interest ?

Thanks.


texts: Generating download.bit from commandline

texts:
We are trying to automate the whole process of building,programming FPGA and launching from Xilinx. Hence,I was programming the FPGA using iMPACT as mentioned in the link, but iMPACT is not generating download.bit from system.bit.

From Xilinx I see that, along with the .bit and .bmm file, we can also assign an "ELF File to Initialize in Block RAM" and currently in the system I am using, it is set to "bootloop" for both the processors. What is this bootloop and where can I find it ? If I can find it, I think I can program the FPGA from the commandline using data2mem.exe. Any help will be appreciated.


texts:
In short, I have a bag that I'm making, the top of the bag is lined with LDR's (3-6), and there's a hidden switch to toggle the alarm on/off. I'm horrible at circuits, but I program, so it looks like this with code :D

IF(ALARM_SWITCH_ON && LDR_LIGHT_SENSED) {

SOUND ALARM }

IF(ALARM_SWITCH_OFF && LDR_LIGHT_SENSED) {

DO NOTHING }

ELSE { DO NOTHING }

A few questions:

Would it be simple to do this?

Would this require programming/PIC chips?

Is there anywhere I could get help drawing a circuit diagram?

Cheers,
Karan


texts: Hearing only noise and ticking sound with simple AM radio - The art of electronics

texts:
I've tried to build the simple AM radio that is proposed at page 56-The Art of Electronics (3rd).

The idea is to tune my radio on a frequency of 657 kHz (I'm sure there's a station at that frequency).
C1 is a variable capacitor between 20 to 55 pf.
The constant R1*C2 = 10^(-4) is chosen to be in between the fast carrier wave (~1 us) and the audibile frequency (~ 200 us).
As an amplifier (in the original circuit it's not shown) I use an op amp with a G=100 and a high pass in input (to prune the DC offset).
As antenna I use a straight long wire (20 meters).
The problem when I build the circuit is that, in the speaker, I hear only a very low static and a periodic tick (I think it's the discharge of the capacitor that gives the tick).
I'm unable to make it work. I think that one of the possible problem is the use of a silicon diode that has too much voltage drop, but before buying a batch of germanium diode to try to fix the problem I wish to hear from expert if that's the actual problem of the radio.
P.S: I'm a beginner.


texts:
I want to design a 3-bit by 3-bit number adder circuit. The result must be in BCD. And I want to show the result by using 7-segment displays.

I built this circuit. I'm not sure from it, and when I run the circuit it doesn't show anything.

Where is my fault?!


texts:
I have a newbie question.
I'm learning about electrical engineering and I bought my first multi-meter. It has a feature called "Continuity Test". I believe this test is to make sure conductors such as wires and cables are continuous and not severed or perhaps you want to find the right circuit.
When I inspect a resistor with the multi-meter probes I can find voltage and current, but when I test for continuity the meter does not beep.
It's as if the two ends of the resistor were not connected somehow. I'm sure this is a laughable question for veteran electrical engineering people but why is it that a multi-meter would not register continuity through a resistor? What goes on in the continuity test so that it registers positive for continuity? Does a certain amount of voltage, current or perhaps the frequency needs to be equal through the circuit in order for the meter to consider continuous?


texts:
I am reading through "Op Amps for Everyone" by Ron Mancini of Texas Instruments and I can't understand why they have made an assumption:

  The specifications for the amplifier are an ac voltage gain of four
  and a peak-to-peak signal swing of 4 volts.

This is the circuit they give:

  IC is selected as 10 mA because the transistor has a current gain (β)
  of 100 at that point. The collector voltage is arbitrarily set at 8 V;
  when the collector voltage swings positive 2 V (from 8 V to 10 V) there is still enough
  voltage dropped across RC to keep the transistor on. Set the
  collector-emitter voltage at 4 V; when the collector voltage swings
  negative 2 V (from 8 V to 6 V) the transistor still has 2 V across it,
  so it stays linear. This sets the emitter voltage (VE) at 4 V.

I can understand this fine. Next step.

This is also fine. However I don't understand the next bit of text:

  We want the base voltage to be 4.6 V because the emitter voltage is
  then 4 V. Assume a voltage drop of 0.4 V across RTH, so Equation 2–35
  can be written. The drop across RTH may not be exactly 0.4 V because
  of beta variations, but a few hundred mV does not matter is this
  design. Now, calculate the ratio of R1 and R2 using the voltage
  divider rule (the load current has been accounted for).

Why did they assume a voltage drop of 0.4V across the Thevenin resistor? If it an assumption, then why say it will be close to this value? How did they arrive at the value of 0.4V?


texts: Possible to cut Heat Shrink tubing lengthwise and reattach?

texts:
I need to get some Heat shrink tubing around something that is too big on the ends for it to slide over.  Is it possible to cut the heat shrink along it's length and somehow reattach it before applying heat to get it to shrink?
If you have any alternative suggestions I need the material to be transparent.


texts: Achieving higher current at the lowside MOSFET to pulse LED

texts:
I have attached the following circuits which i have been developing overtime.

The OBJECTIVE is to get as high as possible a current at the gate of the MOSFET (VF1) to achieve faster pulse times of the LED.

My questions are:

-if there is any way to get higher currents at the MOSFET gate closest to the LED

-I am having trouble getting a higher voltage drop at the LED (VF2), adjusting the supply voltage VS1 has not contributed to increasing voltage across the LED

-the first circuit uses two mosfets and the second circuit uses an NPN/PNP BJT totem configuration to get higher current at the gate of the power MOSFET. Which of the two configurations should i pursue if my goal is to get faster switching at the MOSFET near the LED?

The circuit file is attached as well as the transient graphs. Any help/advice is welcome.


texts: Why do my servos jump to one side when i turn on the power supply?

texts:
I have created a circuit with an Arduino Uno with a joystick, controlling two standard servos. I have connected these servos to a 5V power supply.

The problem is that often when I turn on the power supply, both servos turn completely to one side, clockwise. I then have to turn the servos back manually for the circuit to work.

How can I fix this problem?

Here is the code:


texts:
By now, through-hole components have almost completely disappeared from consumer devices and also professional PCBs.

But what is the alternative to build breadboard-veroboard for SMT technology? Prototyping will be confined to simulators and custom boards?

I know that there are sockets or adapters for some SMD integrated circuits for through-hole boards, but I don't think at this like a definitive solution; I wonder when TH will disappear, what will be the common way to design prototypes?

I'vre read all the answers until now, and somehow I agree, but the basic question is: thru-hole components and breadboard will continue to have an use also in 10-20 years?

(I couldn't find this question anywhere, but tell me if there is)


texts: Crossfading between 2 audio signals / single supply opamp circuit

texts:
Will this circuit work? Any comments? Thanks!

Edit :
by "work" I mean I can blend the 2 audio signals in any ratio with the pot;
it would be an OPA2132 opamp;
input would be audio signals in the range of 0-3.3v

it seems even this circuit would work?


texts: Servo responds to servo tester, not to microcontroller. Signals look the same

texts:
I have a TowerPro MG90D servo (Manufactuer Link) (ServoDatabase Link).
It has a 180deg range (non-continuous).

It responds great to my servo tester:

Observe the following 7% Duty Cycle (about 90 deg) on the tester:

Servo responds fine.

However, when I use servo.write() with my Arduino Mega 2560 clone, the servo does not respond to any angle output. I have several other servos that work just fine with the same code on the same pins.

Observe the following 7% Duty Cycle on the Arduino with servo.write(90):

No response. The servo is "limp"; it is not holding any position.

While I was writing this question, I thought of trying servo.writeMicroseconds().

Here is servo.writeMicroseconds(1450):

Servo responds!

Here is servo.writeMicroseconds(1472) (working), which has the same time intervals as the prevoius non-working servo.write(90)!

servo.writeMicroseconds(1550) (working):

What is the difference?
The servo tester worked at 49.5Hz, while servo.write() failed at 49.9Hz. I wondered if somehow that 0.4Hz made a difference, but then I see that servo.writeMicroseconds() worked at 49.9Hz too.

In the above scope captures, it can be seen that both servo.write(90) and servo.writeMicroseconds(1472) have the same time intervals:
 1,474,560ns HIGH
18,544,640ns LOW

The signals are so similar... What could cause servo.write() not to work?

My code is as basic as possible:

#include <Servo.h>
Servo serv1;

void setup() {
  serv1.attach(3); // Pin 3
}

void loop() {
  serv1.write(90); // No response
  delay(3000);

  serv1.writeMicroseconds(1472); // Works
  delay(3000);

  serv1.write(0); // No response
  delay(3000);

  serv1.writeMicroseconds(1800); // Works
  delay(3000);
}

simulate this circuit – Schematic created using CircuitLab


texts: How can I determine the current rating of a capacitor?

texts:
I haven't seen any capacitor with the "Ampere" rating written over its body. Usually they have max. voltage and capacitance ratings, can i know "current" rating from both values?(Supposing AC voltage)

is it simply voltage/reactance ?


texts: I'm building a circuit that uses multiple chips. All of them require a capacitor to be connected in parallel to the VCC line (as seen in the datasheets). Since capacitors are used to reduce voltage fluctuations, and all the chips are drawing upon the same VCC, can I just use one big capacitor for all the chips? If yes, do I just add the capacitance of the small ones together use that value for the big one?


texts: How to simulate LVT BiCMOS PSpice models?

texts:
I'd like to simulate the digital 74LVTxx chips with their analog characteristics. Packages like Multisim and OrCad only have the basic models (e.g. 74LS04N).
============= SPICE Model =================
.MODEL 74LSIC04 d_chip ( behaviour= "
+; 74LSIC04 Hex Inverter
+/inputs 1A 2A 3A 4A 5A 6A
+/outputs 1Y 2Y 3Y 4Y 5Y 6Y
+/module INV08
+/inputs A
+/outputs Y
+/table 2
+; A  Y
+  L  H
+  H  L
+/delay 1
+; input output Rise time Fall time
+   A          Y      15n         15n
+/endmodule
+/instance INV08 1A 1Y
+/instance INV08 2A 2Y
+/instance INV08 3A 3Y
+/instance INV08 4A 4Y
+/instance INV08 5A 5Y
+/instance INV08 6A 6Y
+")
============= Model template =================
a%p [%t1A?%t:d%t;1A
+      %t2A?%t:d%t;2A
...
+      %tVCC?%t:d%t;VCC
+      %tGND?%t:d%t;GND] %m

I went to NXP and downloaded the circa 1999 PSpice file holding a family of 74LVP models called lvtps.cir. Trying to import this into Multisim resulted in an unconnected spaghetti network. Editing a similar part with this *.cir in the DB editor led to many, many errors. OrCad has no idea what to do with it. Only Cadence PSpice could "simulate" the lvtps.cir file, but that doesn't help me add a 74LVTxx chip to a schematic.
LVT PSPICE MODELS
**************************************************************************
* LVTPS.CIR
* Low Voltage BiCMOS Logic
* Logic Products Group
* Philips Semiconductors
* 3/9/99
* Version 1.02
* Revision Comment: Subcircuits added for expansion of available LVT
* device simulations.
...
**************************************************************
* PACKAGE MODELS
.LIB "lvtpkps.s"

* SUBCIRCUIT MODELS
.LIB "subps.lib"

**************************************************************
* UNCOMMENT ONLY THE DEVICE MODEL FILE DESIRED
* NOMINAL, SLOW, AND FAST FAB PROCESS CORNERS

* NOMINAL PARAMETERS
  .LIB "nomps.lib"
...

Question: How to simulate these 74LVTxx models?* Does this cir file need to be flattened by hand?

*Not asking for a software recommendation as I have a few.


texts: Can't get sine wave out of this circuit in Proteus. Can you help me, please? I'm suppose to have sine wave generator with range 1 kHz - 200 kHz. While googling came across the current circuit, but can't get it work. It's showing DC output e.g. straight line without any shape or change. Can you help me?


texts: Singled ended or Differential - Engine Control Unit

texts:
I know this topic has been beaten to death but I still have not got a clear understanding. Pardon me for my bad explanation as I am an automotive engineer by trade.

I am simulating an engine knock event using a signal generator, which is basically a voltage signal in the range -5v to +5v and feeding it to an engine control unit (black box) to validate few functions. But the hardware documentation of the engine control unit mentions that it requires a knock signal from a differential knock sensor(Input + & Input - and no ground wire). The signal generator is a single ended signal and the pinouts of the signal generator are Input + and GND. My question is would the signal from the signal generator be compatible with the engine control unit?.

Thank you in advance.
Vish


texts: If I were wanting to drive i.e. industrial relays which require 24v from a Microchip PIC what would I need to look at in terms of a general transistor circuit (and it's pitfalls when driving such a component).


texts: Is inconsistent charging bad for batteries?

texts: I am designing a generator for a bench press that generates electricity when you work out, but it would charge the battery inconsistently and I don't know if that would be bad for a battery.


texts: In search of a component or device that switches multiple lines based on input selection

texts:
Okay so the foundation for my curiosity is that in dealing with Arduinos, I found they can be used to program the similar but smaller ATtiny chips.  This is the main hookup configuration that some of you may be familiar with if you've done this before.

My problem then is I want to create a shield that sits atop the arduino and has multiple sockets for ATtinys, and a selector switch that allows for choosing which ATtiny is being programmed to.

I actually did make a prototype, and here's what it looks like.

Not the easiest thing to solder!

So it just has a power switch and a simple single pole triple throw.  Now I figured the best way to do it was to connect all of them to ground, and let the SPTT choose between which was powered.  And in order to make the board as simple as possible, I connected the 4 data lines (3 green and 1 yellow in the picture) straight down and all 3 ATtiny's are connected in parallel to the data, regardless of if they are powered.

Of course this board fails though because I incorrectly assumed there would be no leakage through the ATtiny's data lines, and there is, so the other 2 that aren't being programmed weakly connect through the micro to their respective grounds.

Here's a schematic of it, just pretend it's a SPTT instead of SPDT.

Okay to the point.  Effectively what I want is a device that performs this function.
Would this be considered a mux?


texts:
I've been (re)learning microcontroller programming using AVR ATinys (13/45/85). One reference on digital outputs said that I should sink outputs, but nearly all of the circuit examples I've seen online source them.

Which is right/generally better? If the answer is "it depends" would you mind providing guidelines for when each is better (in the case of ATiny digital outputs).


texts: What kind of electronics (if any) would stop functioning if earth's magnetic poles suddenly switched places?

texts:
If earth's magnetic poles suddenly switched places, would electronics continue working as normally?

Would there be any visible signs in the electronics that a pole shift has taken place?

How about if there was a hypothetical situation of the pole rapidly shifting back and forth during a 24 hour period and then stabilizing?

Would this sort of thing affect any electronics at all? If it would, how?


texts:
I'm trying to build a small sized ultrasonic cleaner. I bought a couple ultrasonic transducers (ranging between 40kHz - 102kHZ and 15 - 35 watt) which I want to play around with.

There are already quite some driver boards and transducers out there, but I really want to keep a small form factor. Also I try to make a setup where I can easily play around with different transducers, so be able to change the frequency and supply voltage with little effort

I was thinking about creating a setup with Arduino so I can easily and precisely change the PWM frequency. I found the circuit below as a starting point from Ultrasonic schematic source:

I'm trying to control a 35W 40khz transducer which is widely available: transducer link

Now I changed the first 555 timer part of the circuit with the Arduino. Resulting in the following:

But for one reason it's not working properly. It's drawing some current but not very much and seems not to do so much. As a power supply I'm using a simple bench-top power supply (0-30v, 5A)

What am I doing wrong and is there otherwise another way I could drive the Ultrasonic transducer using an Arduino?


texts: ELAN EM78P156NP microcntroller programming

texts:
I am writing program for ELAN EM78P156NP using WisePlus C Compiler ,but my program is not responding when written on micro controller.I am putting the code below please let me know what is wrong with the code.
I am just trying to blink the LED on PORT 5 and PORT 6 of the microcontroller
Please help me...

unsigned int PORT6 @0x06: rpage 0;
unsigned int PORT5 @0x05: rpage 0;
int delay()
{
  int i;
  for(i=0;i<1200;i++);
  return 0;
}

void main()
{
  PORT6=0x0000;
  PORT5=0x0000;
  while(1)
  {

   PORT6=0xffff;
   PORT5=0xffff;

   delay();
   PORT6=0x0000;
   PORT5=0x0000;

   delay();

   }
}


texts: I can't get WDT (watchdog timer) working on ATmega2560

texts:
I have a running application on the ATmega2560 and it is working OK.
Now, I wanted to implement Watchdog feature in order to reset the chip when the application takes longer to operate for some reason.

I am using Visual Studio with Visual Micro extension.
And I flash the HEX file via AVRISP mkII.

So, I have simply started with couple of samples found on the net.
But, whatever WDT version I used they repeatedly restarted the chip on and on endlessly.

Here is one of them;

#include <avr/wdt.h>

int loop_count = 0;
int wdt_counter = 0;

void setup() {

    Serial.begin(9600);
    Serial.println("Starting up...");
    pinMode(10, OUTPUT);
    digitalWrite(10, HIGH);
    delay(500);
    watchdogStart();
}

void watchdogStart(void)
{
    cli();  // disable all interrupts
    wdt_reset(); // reset the WDT timer
                 /*
                 //WDTCSR configuration:
                 WDIE = 1: //Interrupt Enable
                 WDE = 1 : //Reset Enable
                 WDP3 = 0 :
                 For 2000ms Time-out WDP2 = 1 :
                 For 2000ms Time-out WDP1 = 1 :
                 For 2000ms Time-out WDP0 = 1 :
                 For 2000ms Time-out
                 */
                 // Enter Watchdog Configuration mode:
    WDTCSR |= (1 << WDCE) | (1 << WDE); // Set Watchdog settings:
    WDTCSR = (1 << WDIE) | (0 << WDE) | (0 << WDP3) | (1 << WDP2) | (1 << WDP1) | (1 << WDP0);
    sei();
}

void watchdogArm(void)
{
    cli();  // disable all interrupts
    wdt_reset(); // reset the WDT timer
                 /*
                 //WDTCSR configuration:
                 WDIE = 1: //Interrupt Enable
                 WDE = 1 : //Reset Enable
                 WDP3 = 0 :
                 For 2000ms Time-out WDP2 = 1 :
                 For 2000ms Time-out WDP1 = 1 :
                 For 2000ms Time-out WDP0 = 1 :
                 For 2000ms Time-out
                 */
                 // Enter Watchdog Configuration mode:
    WDTCSR |= (1 << WDCE) | (1 << WDE); // Set Watchdog settings:
    WDTCSR = (1 << WDIE) | (1 << WDE) | (0 << WDP3) | (1 << WDP2) | (1 << WDP1) | (1 << WDP0);
    sei();
}

void loop()
{
    for (int i = 0; i <= loop_count; i++) {
        digitalWrite(10, HIGH);
        delay(100);
        digitalWrite(10, LOW);
        delay(100);
    }
    loop_count++;
    wdt_reset();
    watchdogStart();
    wdt_counter = 0;
    Serial.print(loop_count);
    Serial.print(". Watchdog fed in approx. ");
    Serial.print(loop_count * 200);
    Serial.println(" milliseconds.");
}
/* this is called when the watchdog times out and before the reset */
ISR(WDT_vect) // Watchdog timer interrupt.
{
    if (wdt_counter == 0)
    {
        wdt_counter++;
        watchdogArm();
    }
    // Include your code here - be careful not to use functions they may cause the interrupt to hang and // prevent a reset.
}

Fuses used:

I am about to conclude WDT is not really working with ATmega2560.
I would like to hear your opinions and most desirably a reliable working solution sample?


texts: Help identify IC with erased label by using pin connections in the schematic

texts:
I am reversing a board which some of its IC labels are erased by the manufacturer. I've drowned its schematic in the picture below. The label-removed ICs in the schematic are IC5, IC8, and IC13 which are marked in the picture.
The table of resistor values is attached and all of the electrolyte capacitors are 10uF 50V except C9, C10.
I have also attached the pictures of the ICs on the board.

The board connects to a motherboard by a 3*32 pin connector which is shown by a rectangle sign with its number in the schematic. I found a text about this board that says the board's job is analog processing of values measured by other motherboard's cards.

From the schematic, I guess that IC13 is a kind of switch-mode power supply and IC5 is maybe a quad digital to analog converter.
I searched in datasheets but still, I couldn't find any IC with input and output pins accorded to the schematic.

I hope you can help me to identify the marking code or the family of unknown ICs (IC5, IC8, IC13).


texts: How do I tune a low frequency series resonant circuit?

texts: I am driving a 2.2mH inductor and 736pF cap at 125kHz with a h-bridge trying to make a resonant circuit. My power source is 2.5V. Man, I am having a lot of trouble. I can get to 20V p-p in a signal generator setup driving the h-bridge but only 8V p-p when I solder in the same 1% caps on a uC prototype. I have seen advice on trimmers but I am interested in a digital solution or auto tuning. Does anyone have a schematic of fet switched bank of caps so I could what it looks like? Could I do it with only 2.5V available for the fets? Thanks.


texts: Design R C snubber for flyback converter

texts:
I have a DC/DC flyback converter and I need to design a snubber.

I already know the diode to use I just need to design the R and C value. Now, I have simulated my circuit and tweaking values on C and R I came out with C=680uF and R=2.2kOhm; the problem is they are simulated values and I've really not applied any formula.

Iknow that the diode will have a $$V_{DS}^{max}=V_{IN}+V_{C_{SN}}+\frac{\Delta V_{C_{SN}}}{2}$$ and $$R_{SN}=\frac{2V_{C_{SN}}(V_{C_{SN}}-\frac{n_1}{n_2}V_{out})}{L_df_ci_1^2}$$ and $$C_{SN}=\frac{V_{C_{SN}}}{R_{SN}f_C\Delta V_{C_{SN}}}$$

Now my Vin=12V, Fc=50KhZ, the V_DS max on the transistor should be 17V and the max I_DS on the same transistor is 2.1A (n1/n1=1 and k=0.996588)

I really can't figure it out how to put together the data and actually calculate R and C for the snubber

I put a random diode in the schematic as the one I use on the project is an MBR1045

simulate this circuit – Schematic created using CircuitLab

This is V on the primary and V on the secondary... Now I'm checking the secondary it seems bad, really

This is VDS

And this is Vout


texts:
I got this really cool idea the other day. Sitting in my Computer-Sci Lab at school I saw the binary clock on the wall. As a "watch guy", I immediately wanted a watch like it. I've always had a DIY attitude, so I looked in to it, and I was wondering:

How can I program an LED Matrix? I know I would have to use some kind of arduino, but I am very unfamiliar with all the lingo. I was wondering if there is some kind of set up that allows me to program one of these in a way similar to programming a computer?


texts: Problem with crystal oscillator based RF circuit

texts:
As a little experiment, a friend and I are trying to get a crystal oscillator based transmitter and receiver to work. So far we're having no luck.

Here are the wiring diagrams:

We once got the transmitter to send on 27MHz, but with a very erratic signal.  We used a digital oscilloscope to verify. The wire wound inductor on the receiver is hand made from a ferrite core.

I have also been told that using a breadboard can add a capacitance effect and throw the crystal oscillator out of balance.  Is there any way to counter or compensate for this?


texts: What's the advantage of PAM modulation over QAM?

texts:
What are the main advantages of PAM (Pulse amplitude modulation) modulation over QAM ?

Ethernet is using PAM for 1000BASET and 10GBASET, but any other high speed links use QAM like DOCSIS, ADSL/VDSL or any RF transport.


texts: Max input voltage to soundcard for use with Visual Analyzer?

texts:
I am using the line input on my PC's soundcard (Realtek High Definition Audio) in order to use a software oscilloscope program (Visual Analyzer - www.sillanumsoft.org). I want to be sure not to damage the soundcard with too large an input voltage. I can't find any specs for this soundcard, but since it's designed to be used for audio signals, I'm thinking that I should certainly be safe to at least 1 - 2 volts p-p. Can someone with more knowledge of analog to digital conversion to a soundcard input please help me with this? Since I may want to examine a slightly higher voltage (maybe a non-audio signal), this limit is necessary for me to know. Thanks in advance.

I'm a stack newbie and should have researched a bit more before asking this question- I found understanding at https://en.wikipedia.org/wiki/Line_level. I'm using the line in, never the mic input. I'm an electronics technician, but I have no idea how to check my card's input impedance properly as Marcus suggested. I'm guessing that I'd need to choose some nominal frequency to approach measuring impedance (maybe 400hz) - but I'm used to analog mics, amps and speakers - no idea how to approach analyzing the impedance of an analog to digital input.


texts: Second order High pass Butterworth Filter design

texts:
I am studying the designs of Second Order Butterworth high pass filter practically.

The Capacitor values C1 and C2 described in standard textbooks are always in the range of picofarads.(e.g.,0.0047uF)

1.The input signal is Sin wave(Range of frequency- 10Hz to 1MHz) given by the Function Generator.

2.I use standard DSO to monitor input and output at Vin and Vout Terminals.

3.Op-amp used in the practical circuitry is 741.

If I design the value such that the capacitor value is 1uF(with designed resistance value as 530 ohms for Cutoff frequency fc=3Hhz)) then the Signal Input which was given by the function generator itself distorts.Why so?

Why is the input signal(at Vin) given from the function generator(Datasheet) should distort depending on capacitor values?


texts: Voltage difference on DSO-150 'scope' and Fluke 87 multimeter

texts:
I am attempting to use a ESP32 to make a Yamaha Receiver internet connected through the receiver's cabled connection to pass remote button presses. I have found a manual detailing the protocol and right now I'm attempting to get the ESP32 to trigger based on the signals.
Both scope and multimeter are attached at the same point in the circuit, I think using the same polarity. The receiver specifies to use a mono-audio cable which I replaced by a stereo 3.5mm audio cable. I have attached the red lead of the multimeter and the scope probe tip to the tip of the audio plug. I have attached the ground lead of the probe and the black COM lead of the multimeter to the bottom-most surface on the audio plug.
The protocol is serial and very slow (1ms minimum between edges) so it is well visible on my very rickety and cheap scope, a DSO-150. However, the measured voltages don't match with the readings of my inherited Fluke 87. In rest, the scope reports a voltage of around -2V, using 0.5V/div The Fluke measures 0V set to the tens-range. I expect a resting voltage of 0V.
I don't expect the Fluke to accurately measure the peak voltage of the signal. The scope indicates it is 4.5V peak to peak, which doesn't seem implausible to me. That, combined with the fact that the waveform of measured signal exactly corresponds to what the manufacturer's documentation states leads me to believe the scope is attached correctly.
What could explain the difference in resting voltage measurement?


texts: Less voltage more amp? switch characteristis

texts:
I have a question regarding switches, relays etc

Ex, if I have a switch rated for 24v 0.5a, can the contacts then safely handle 12v up to 1a? Because the power passing the switch is the same? Or should I anyway use a 12v 1a switch?


texts: Half Bridge Gate Drive Transformer - Extra winding?

texts:
I've been experimenting on a lot of half-bridge-based PC PSU schematics. There's one thing I cannot understand:

As can be seen from above, there's an extra winding in series with the high side driving winding (marked with red ?) and one end of it goes directly to the primary of power transformer.

What is its purpose?

Thanks.


texts: How do I manage a large array of "motion sensors" and lights?

texts:
I'm a web developer / system admin and I have a client project with a project that is just beyond me. In a nutshell, we need to the following capabilities:

Track the status of hundreds of Passive Infrared Sensors
Track the status of hundreds of lights (not sure yet whether it will be a simple BOOL value or a percentage / brightness value)
Trigger any of the lights individually or in groups from a main console and eventually from mobile apps
Log all of the state changes for the motion sensors and lights
Generate reports and pattern analysis based off the logs

The programming involved will be cake. I understand how that works.. but where do I even start in controlling lights and tracking that many streams of external input? What hardware and software should I be looking at? Can I build this on top of a linux server for easier access from a mobile device?


texts:
I am trying to find a schematic for a test jig.  I have  quite a few 2N5886 and MJ15003 TO3 transistors that I purchased and would like to make sure they meet specs.  Short of building a separate regulated 28 volt supply and putting them in it, how can I test these transistors to make sure they are not going to fail in circuit when being called upon to deliver 28v at 10 amps (for a pair)?

Thank you.


texts: Verilog - Name is optional when instantiating primitive gates

texts:
Why is the name optional when instantiating primitive
gates, but not optional when defined modules are instantiated ?

EDIT (EXAMPLES)

// Instantiate primitive gates
xor (S, x, y);
and (C, x, y);
endmodule

vs

// Instantiate half adders
half_adder HA1 (S1, C1, x, y);
half_adder HA2 (S, C2, S1, z);


texts: Can I use a Class D amplifier as a summing amplifier?

texts:
Context: I'm creating a mono, battery powered speaker. I'd like to sum the left and right channels of a stereo input signal into a mono output signal, which I feed into a Class-D Mono Audio Amplifier to drive the speaker.

The stereo-to-mono solution I've decided on is to create a summing amplifier with unity gain, and I'd like to keep my circuit simple by using the Class D amp in place of the op amp.

Will this work? Or do Class D amplifiers work too fundamentally differently from a regular op amp?

simulate this circuit – Schematic created using CircuitLab

EDIT:

Here's my revised circuit diagram, based on what I learned from the answers below. I've opted not to DC-decouple for the moment, but I haven't yet tested this.

simulate this circuit


texts: Coupled Inductor/Magnetic Circuit Behavior

texts:
I seek an intuitive understanding of a coupled inductor in a system.  My professors, a generation ago, bemoaned that they'd had four semesters of magnetic circuits but had time to give us just one course including motors.  This, I suspect, is what I missed.  Please start with a general description before diving into the differential equations!
Take a core (such as a ferrite toroid) with two windings.  Assume we will not saturate this core.  Designate one winding primary and one secondary.  The secondary has a non-reactive load.  It may be linear (resistive) or non-linear (eg. resistor plus PN junctions).
Apply a voltage to the primary from a current-limited DC source.  A voltage will appear across the secondary, and current will flow as the primary current increases.
What is happening with the fields from each winding?  What energy does each hold?
Now the power source reaches its current limit.  With no increase, how do the voltage and current in the secondary act?  How does this affect conditions in the primary?  As time goes to infinity, I expect the secondary current to go to zero and the primary's field to store energy equivalent to that stored in a simple inductor.  Is this correct?  How do the fields, currents, and voltages progress through time to reach this state?
If it will simplify the description, feel free to replace the voltage source with a variable current source which is ramped up at a slow, constant rate from zero to the final value.
Sorry it took so many words to describe.  I hope the problem is clearly described.  Thank you for aiding my education.


texts:
For a typical mic a singer uses in a concert, how much current is generated when the singer sings? The current transmitted from the diaphragm into the wire.

What does the following specification tell us about the value I am looking for, for example?


texts: Active Mixer RF Input Power and Input IP3i, P1dB Question

texts:
I am new and learning in this field.

The received signal is first amplified with SKY65404 LNA and secondly with HMC313 Amplifier. Lastly it is connected to Active Mixer ADL5801's RFIN pins.

In ADL5801's mixer datasheet, i could not find what is the maximum rf input power accepted in decibels. LO level is given in datasheet as -10 to 10 dBm. The datasheet gives information about Input IP3 and Input P1db values but i do not know how to read them.

My questions are:

How can i learn what is the max. allowed rf input power for mixer so i can select amplifier.
Does Input IP3 and Input P1db give any information related to the first question or how should i interpret them.
How should i calculate the received signal's power from antenna. I mean it is said the rf signal gets so weak in the air to nano or micro volts. What value is the start point as decibel to start adding gains of amplifiers so i calculate mixer input level correctly.

Thank you.

ADL5801 Datasheet


texts: Why is PIC Programming Voltage Higher Than Vsupply

texts: I work with PIC microcontrollers quite a bit and have never understood why Vpp (programming voltage) is higher than the max supply voltage that powers the PIC?


texts:
When there is an n-mesh circuit, we define n independent mesh equations for the unknown n currents. While doing this, we use an assumption that each mesh has a separate current flowing around it.

I don't understand this assumption. How do we do it? What is the proof that an assumption like this will work? And, you should know that a statement like "I tried this a billion times and it worked every time." is not a solid mathematical proof. There must be an untold background of this theorem. Is it related to the Stokes' Theorem by any chance?


texts:
I have designed a CPU that works in simulation using Verilator, and would now like to test it in hardware on an FPGA. A quick way to get to the testing phase would be to embed a program to run on the CPU into memory on the FPGA itself, then read instructions from it.

I have read about the $readmemh(...) function that reads data from a .mem file into some memory structure but I am not sure how to make this happen during synthesis. I tried using an initial construct but learnt that this was only run in simulation. How would I go about embedding data into the FPGA at synthesis?

In the future I would devise some way of loading a program at startup over serial or reading instructions from something like flash storage that could be programmed separately (similar to how an ATMega is programmed).

My RAM module is:

`timescale 1ns / 1ps
`define SIZE 512
`define ADDR(address) address[8:0]

module mem(
    /* verilator lint_off UNUSED */
    input [15:0] address,
    /* verilator lint_on UNUSED */
    input [31:0] data_in,
    output reg[31:0] data_out,
    input read,
    input write,
    input clk
);

reg[7:0] data[`SIZE-1:0];

always @(negedge clk) begin
    if (write) begin
        data[`ADDR(address)] <= data_in[7:0];
        data[`ADDR(address) + 1] <= data_in[15:8];
        data[`ADDR(address) + 2] <= data_in[23:16];
        data[`ADDR(address) + 3] <= data_in[31:24];
    end
    else if (read) begin
        data_out[7:0] <= data[`ADDR(address)];
        data_out[15:8] <= data[`ADDR(address) + 1];
        data_out[23:16] <= data[`ADDR(address) + 2];
        data_out[31:24] <= data[`ADDR(address) + 3];
    end
end

endmodule

The data structure is where I would like to embed the bytes from a file.


texts:
Over the years I have always wondered why we do not make more use of resonance when driving things like solenoids and relays.

We all use the circuit below ad-infinitum and just tolerate the current and power loss involved in holding the solenoid or relay in place. Power that actually does no work.

simulate this circuit – Schematic created using CircuitLab

It has always seemed to me that, since the coil is a nice little inductor anyway, we could use a resonant oscillator to drive them instead? Perhaps something like a typical Colpitts.

Now granted, the coil would need to be different. Higher inductance and lower series resistance than your typical off-the-shelf relays and solenoids. But it seems to me with the right coil and capacitors you could keep that coil activated for a very long time while using minimal current to keep the circuit resonating.

The magnetic field would of course be oscillating and less intense on average, but the frequencies involved would be high enough to be beyond the reaction time of the mechanics, and the intensity thing can be compensated for in the ac design.

I do of course realize you would still have to replace the IR losses.

My gut tells me there is something fundamental I am forgetting or not considering here. In fact I am having a hard time getting my old head wrapped around what the mechanism is and how the IR losses relate to the resonant current VS. DC current. Searching the internet has not yielded anything useful.

What would prevent this from working? Has anyone tried this in practice?


texts: Reproduce 2CH Relay Optoisolated on custom PCB

texts:
I'm designing a custom PCB that implements a relay section.
I would "reproduce" the schematic of the 2 Channel Relay optoisolated so common in hobbystic.
The selling shield is

And the schematic is:

My trouble are the following:

1) The transistor is the J3Y. Can I replace it with a 2N2222(A) TPH? From datasheets they seems very equivalent

2) The diodes seems Zener, for red colour. Any chance to get the exact type? It is impossible to read.... Or I will use a normal diode, a 4001

3) The optoisolator is PC817. I have available for the moment only the CNY758. What I need to check on the datasheet to verify is they could be swapped?

Thank you very much


texts: ATMega328P free-running ADC interrupt not firing

texts:
I'm playing with an ATMega328P running off a USBtiny 1.0, and have the following set up:

Potentiometer to ADC0.
PB0 sourcing current for a LED.

My program then mirrors ADC0 to the PWM on PB0, so the position of the potentiometer directly controls the brightness of the LED.

This works when it is done inside the infinite loop at the end of main(), but if I move it to the ADC interrupt, nothing seems to happen (see "Remove me" comment).

I'm partially basing this off a tutorial at http://www.avr-tutorials.com/adc/utilizing-avr-adc-interrupt-feature, but using free-running mode.

#define __AVR_ATmega328P__
#define F_CPU 1000000UL
#include <avr/io.h>
#include <avr/interrupt.h>

#define SET(register, bit) register |= _BV(bit)
#define CLEAR(register, bit) register &= ~_BV(bit)

int main(void) {
    // Set up ADC0 as a 8-bit potentiometer input.
    // -------------------------------------------------------------------------

    // Switch from 10-bit to 8-bit mode.
    // Our output is 8-bit anyway.
    SET(ADMUX, ADLAR);

    // Use AVCC as the reference for the ADC.
    SET(ADMUX, REFS0);
    CLEAR(ADMUX, REFS1);

    // Specify that we are only interested in ADC0.
    CLEAR(ADMUX, MUX0);
    CLEAR(ADMUX, MUX1);
    CLEAR(ADMUX, MUX2);
    CLEAR(ADMUX, MUX3);

    // Set the clock divider to 128x.
    // TODO: Experiment with reducing the divider when logic is in.
    SET(ADCSRA, ADPS0);
    SET(ADCSRA, ADPS1);
    SET(ADCSRA, ADPS2);

    // Set to free-running mode; the ADC will run continuously.
    CLEAR(ADCSRB, ADTS0);
    CLEAR(ADCSRB, ADTS1);
    CLEAR(ADCSRB, ADTS2);

    // Enable auto-triggering of the ADC by the above.
    SET(ADCSRA, ADATE);

    // Fire the ADC interrupt when a sample is ready.
    SET(ADCSRA, ADIE);

    // Enable the ADC now it has been configured.
    SET(ADCSRA, ADEN);

    // Start the free-running timer.
    SET(ADCSRA, ADSC);

    // Set up LED output on PB1.
    // -------------------------------------------------------------------------

    // Set the pin up as an output.
    SET(DDRB, PB1);

    // We'll be comparing a timer (sawtooth) to a value (OCR1A);
    // the pin will be high or low depending upon whether the timer is greater
    // or lower than the value (OCR1A).
    SET(TCCR1A, COM1A1);

    // Switch to fast PWM.
    // This doubles the frequency, but means that phase shifts when OCR1A is
    // changed.  Doesn't matter for us.
    SET(TCCR1A, WGM10);
    SET(TCCR1B, WGM12);

    // Disable the timer divider; as fast as possible.
    SET(TCCR1B, CS10);

    // Enable interrupts now everything is configured.
    // -------------------------------------------------------------------------
    sei();

    while (1) {
        // Remove me to have the ADC interrupt set the LED brightness instead.
        OCR1A = ADCH;
    }
}

// This ADC interrupt handler is called every time a potentiometer sample is ready.
ISR(ADC_vect) {
    OCR1A = ADCH;
}

I've also experimented with the INT0 interrupt in another program, but that also seemingly doesn't fire the interrupt handler.

avr-gcc version:

Using built-in specs.
Target: avr
Configured with: ../gcc-4.3.3/configure --enable-win32-registry=WinAVR-20100110 --with-gmp=/usr/local --with-mpfr=/usr/local --prefix=/c/WinAVR --target=avr --enable-languages=c,c++,objc --with-dwarf2 --enable-doc --disable-shared --disable-libada --disable-libssp --disable-nls --with-pkgversion='WinAVR 20100110' --with-bugurl='URL:http://sourceforge.net/tracker/?atid=520074&group_id=68108&func=browse'
Thread model: single
gcc version 4.3.3 (WinAVR 20100110)

I'm probably missing some setup, but haven't been able to find anything I haven't done.  Can anyone see what I'm doing wrong?  Thank you.


texts: layering high dielectric constant and high dielectric strength materials in a capacitor

texts:
I'm trying to get a better understanding of the relationship of dielectric constant (relative permitivity) to dielectric strength (breakdown voltage).I want to know what happens when you layer materials of high dielectric constant but low dielectric strength with materials of low dielectric constant but high dielectric strength. For example Barium titanate has a dielectric constant of 1200, But a dielectric strength of only 1.2 Mv/m. Mica has a dielectric strength of 118 Mv/m, but a dielectric constant of only 3.

If you put a 1mm sheet of mica between 2 1mm sheets of barium titanate, what would be the combined dielectric constant and dielectric strength?


texts: I am working on a vehicle with batteries, but i am not quite sure if my grounding solution/design is correct. It is supplied with two 12VDC batteries in series, connected to a DC-DC (24VDC-24VDC) powersupply. Basically i always ground the 0V to the chassis, and use a 2-pole MCB after the batteries and 1-pole to devices. Is this a bad design?


texts:
Can a Servo motor (or any electric motor) be used as a load on a system ? meaning can it reprisent for example a certain dead weight ?

In the picture below you can see a motor driving 3 gears, to apply a certain load on the system could i put another motor on the other end ? will that burn the motor ? how would the load be applied should the second motor receive current ? or run in reverse ?


texts: Designing a Moore sequence detector using three always blocks

texts:
Trying to implementing a Moore state machine using three always blocks. The Moore state machine has two inputs (ain[1:0]) and one output (yout). The output yout begins as 0 and remains a constant value unless one of the following input sequences occurs:

(i) The input sequence ain[1:0] = 01, 00 causes the output to become 0
(ii) The input sequence ain[1:0] = 11, 00 causes the output to become 1
(iii) The input sequence ain[1:0] = 10, 00 causes the output to toggle.

module moore_sequence_detector_3_blocks(
input clk,
input reset,
input [1:0] ain,
output reg yout
);
reg[2:0] state, nextstate;
parameter S0=0, S1=1, S2=2, S3=3, S1_To_S0=4, S2_To_S0=5, S3_To_S0=6;

always @(posedge clk or posedge reset) // always block to update state
    if(reset)
    begin
        state <= S0;
    end
    else
    begin
        state <= nextstate;
    end

always @(state or ain) // always block to compute nextstate
begin
    case (ain)
        2'b00:
            if(state == S1)
                nextstate = S1_To_S0;
            else if(state == S2)
                nextstate = S2_To_S0;
            else if(state == S3)
                nextstate = S3_To_S0;
            else
                nextstate = state;
        2'b01: nextstate = S1;
        2'b10: nextstate = S2;
        2'b11: nextstate = S3;
        default: nextstate = S0;
    endcase
end

always @(state) // always block to compute output
    begin
        case(state)
            S0: yout = 0;
            S1_To_S0: yout = 0;
            S2_To_S0: yout = ~yout;
            S3_To_S0: yout = 1;
            default:
                yout = yout;
        endcase
    end endmodule

I cant seem to figure out what is wrong. The states should work as follows

sout0  yout = 0
sout1  yout = 1

swait1  yout = 0
swait2  yout = 0
swaitInv0  yout = 0

swait3  yout = 1
swait4  yout = 1
swaitInv1  yout = 1

swaitInv0 -> sout1


texts:
I accidently shorted pins 10 and 11 with 10 set to output HIGH and 11 set to input. The pin 11 is not working. How do I figure out what component I burned?

Can the problem be fixed?


texts:
I was reading the BJT section of The Art of Electronics on page 77 Figure 2.10.B.
Shouldn't The divider voltage sit at 14.4v rather than 11.6v? the opposite what the author mentioned.
Since if Q3 is in saturation, the base voltage of Q3 should be ~0.6v lower than the collector which is 14.4v.


texts: how to measure state of charge of a battery through algorithm?

texts: How to measure State of Charge(SOC) through algorithm? I found some details about SOC. in that they mentioned it can measure through voltage method, Hydro meter and columb counting etc.. But Through Software algorithm how to measure? I mean what are the hardware inputs we have to give for Software module? If so, How to give that signals to SOftware module.


texts: Need help to design a voltage regulator circuit for two 3v dc motors

texts:
I intend to use two DC 3V motors to make a mini water pump as described in this video.

Here are the specs of my solar panel which i intend to use as power supply for the circuit:

Voltage at max power point=8.2V.
Current at max power point=0.62A.
Nominal voltage=6V.
Power at max power point=5W.

I have two DC motors each of 3V rating.

I don't know the power consumption of this motor under loaded conditions.I  got a datasheet of a motor looking exactly like mine from a website.-->This is the link to it.According to it ,the  motor consumes 0.76A at 1.5V at max efficiency and 1.1A at 3V at max efficiency.

1)Assuming that the panel gives about 3.5 to 4 Watt during the time of usage, how do i convert its output to 1.2A at 3V or to 2.4A at 1.5V with minimum loss?

2)Are LM317 or 78xx series ICs good enough to accomplish the  task?


texts:
I am working on a nixie tube clock design using IN8 tubes and a combination of MPSA42 and MPSA92 transistors to implement a multiplexed design of four tubes. The issue I'm running into now is that when I power the system on and drive one of the tubes' numerals, I get a slight glow out of the other tubes on the same numeral. My anode circuit consists of a mpsa42 connected to the base of a mpsa92 to enable my microcontroller to multiplex between tubes (see anode circuit attachment). The cathode side of the tube has each of the corresponding numeral cathode pins connected to an mpsa42 which is also controlled by the same microcontroller. My plan is to multiplex through the anode of each tube while simultaneously enabling the correct numeral with the cathode side mpsa42.

This all seems to work fine for a single tube, but once I install the other tubes I see that even though I'm driving the anode selects for the unused tubes to zero (IE driving only one of the anode's mpsa42), I'm measuring a voltage across the active numeral of the theoretically undriven tubes. I'm struggling to understand how this is happening, as from what I can tell when probing around, the PNP should not be on so no current should be flowing through it...

I have noticed that when I apply a voltage to a tube's anode (with a series resistor) and ground the cathode that all of the other cathode pins appear to have a voltage on them even though they clearly should be floating. Could it be possible that when I have multiple tubes in parallel and apply a voltage to one of their anodes that the common cathode pins are actually allowing enough voltage to flow back from an inactive cathode to the tubes anode and then back through the "active" cathode (I've tried to diagram this possible current path in the last attachment)? Is this possible with the fundamental nature of nixie tubes? I'm admittedly a bit stumped here as I believe I have seen other circuits of a similar design to mine for controlling nixie tubes, and when modeled in SPICE the circuit works fine (with the caveat that the simulation uses a purely resistive load).

Any help would be appreciated, or any feedback on my circuits since clearly I'm doing something (or understanding something) wrong!


texts: How can IR frequency modulation be used to detect distance?

texts:
The new TSSP4056 proximity sensor from Vishay "determines distance by varying the carrier frequency used to drive the emitter between 30 kHz and 54 kHz, thereby finding the threshold frequency at which the sensor just detects the object." Its data sheet says very little about the function. What is the science behind this? What is the relationship between modulating an IR beam and distance?

The device functions out to 2 meters. Can this range limit be extrapolated from the frequency range (30 to 54 KHZ)?


texts: Importing PSpice Model (.lib) into Proteus

texts:
I know there is a popular tutorial on how to import PSpice models into Proteus here.
The problem is, the PSpice model I have downloaded for FQT5P10 is in the form of .lib
I think that is the reason why it does not have the required lines:
*SCRIPT SPICE
*ENDSCRIPT

So I don't know which lines I should copy for simulation to work. Here is the content of the .lib:
**************** Power Discrete MOSFET Electrical Circuit Model *****************
* Product Name: FQT5P10
* 100V P-Channel MOSFET and SOT-223
*--------------------------------------------------------------------------------
.SUBCKT FQT5P10 20 10 30
Rg 10 1  0.077
M1 2 1 3 3 DMOS  L=1u  W=1u
.MODEL DMOS PMOS (VTO={-3.8*{-0.0005*TEMP+1.0125}} KP={2.45*{-0.00002*TEMP+1.0005}}
+ THETA=0.0576  VMAX=1.0E5   LEVEL=3)
Cgs 1 3 240p
Rd 20 4 0.273  TC=0.0081
Dds 4 3 DDS
.MODEL DDS D(BV={100*{0.000875*TEMP+0.978125}}  M=0.37   CJO=52p   VJ=0.609)
Dbody 20 3 DBODY
.MODEL DBODY D(IS=1.0E-14  N=1.0  RS=0.34  EG=1.18  TT=85n)
Ra 4 2  0.273  TC=0.0081
Rs 3 5  0.022
Ls 5 30 2.6n
M2 1 8 6 6 INTER
E2 8 6 4 1 2
.MODEL INTER PMOS (VTO=0 KP=10 LEVEL=1)
Cgdmax 7 4 380p
Rcgd 7 4 1E7
Dgd  4 6 DGD
Rdgd 4 6 1E7
.MODEL DGD D(M=0.77 CJO=380p VJ=0.44)
M3 7 9 1 1 INTER
E3 9 1 4 1 -2
.ENDS
*-------------------------------------------------------------------------------
* Creation : Feb.-14-2005
* Fairchild Semiconductor


texts: What's wrong with this PWM-controlled constant current sink?

texts:
T10 gets very hot and starts melting within 30s, even with a heat sink and values way below its rated 15A.

Edit:
 I know it is not a true PWM controlled constant current, but that what I can do with the parts that I have access to. As for the current being used at, it does not exceed 4A at full duty of the 65kHz signal.

Edit 2: So, basically, what's wrong with my circuit is my inability to correctly use the information in the datasheet. Thanks for your answers.


texts: Properly connecting Shift-Registers to microcontroller

texts:
While working on a circuit, I am confused on connecting daisy chained 74HCT595 and 74HCT165 to microcontroller.
I am developing the circuit so that microcontroller can be connected as separate add-on module. I am planning to use:

ESP32
STM32

The confusion is that the Shift-Registers refer to SPI communication on some internet sources while others say it is not an SPI device. I did refer to the datasheets which makes no reference to SPI, but I have been able to make these work over SPI.
Question:
Do I need to connect the Shift Registers to SPI (MISO/MOSI/CLK) pins, or can it be connected to any general purpose GPIO on both the above micro controller?


texts: Low Voltage limiter circuit with fast recovery time

texts:
Hello I am having trouble building/finding parts for a circuit that I need to limit the peak voltage of a signal coming from a photodetector.

My problem is that an amplifier I am using will not tolerate a signal above 200mV without damaging the device. My signal is a photomultiplier PL decay curve with a 100-200mV plus peak amplitude, whereas the part of the signal we are trying to observe is four decades lower in the long tail of the decay, hence our needed amplification (it's near the noise of the instruments pre amplification).

My other problem is that the pulse which this 100-200mV peak is part of, is rather fast (50ns). From researching various diodes I've been learning that a schottky diode is either fast recovery or have a low voltage cutoff (at least from what I have seen at mouser and digikey), but not both.

My plan was to build a intermediate circuit between the photodetector and amplifier that cuts off any voltages above, lets say 150mV to be safe, but I am unsure whether or not this is possible giving how low that cutoff voltage is as well as how fast this pulse is.

I welcome all suggestions to this problem, for I am stuck and questioning if this is possible with a basic diode circuit or if another design altogether is needed.

Thank you.

Adam


texts: Identifying natural an forced response circuits

texts:
yesterday my professor introduced us to forced response circuits. I am some what confused on telling the difference when trying to find D.E. for it.

Determine the D.E. governing V(t), t>0.

This is one of the pratice problems he gave us. Now since t>0 the switch is on B, this means we ignore the 2V and 5omh portion of the circuit.

I found that there is 9V across the capacitor and Tau = 6.

This give me V(t) = 9e^(-t/6).

When I looked up a solution(could be wrong) it was V(t) = 9 - 7e^(-t/6).

Could someone explain this? Is this because the circuit is a forced response?


texts:
The following schematic is from Texas Instruments: http://www.ti.com/tool/PMP10195

I have some questions on it:

Is Q1 always on? How do I calculate the voltage that the gate sees? It looks like this voltage is defined by R1, R2, R4, D7, and D8.
The documentation says:  "In order to reduce the stress on the FET, a cascode configuration has been selected". What I understand from this is that Q1 and Q2 share the big VDS voltage, right? However, as Q2 is the one activated by the IC U1, and Q1 seems like is always on, Q1 is protecting Q2, not viceversa. Am I right?

I'm needing a MOSFET which withstands very high VDS voltage (>1kV), so I'm wondering if this configuration is reliable and cheaper than just a single 1.2kV MOSFET that are really pricey.

Note that I'm not asking for specific product recommendation. I'm just asking from a general design point of view.


texts: When we manufacture certain PCBs, where 50ohms impedance matching is required the manufacturer provides a small PCB strip along with the actual PCB. What is the actual purpose of this?


texts: Using LEDs in a bridge rectifier for light, not load

texts:
This is a two-part follow-up question (which wouldn't fit within the 600-character limit for comments) to Using LEDs in a bridge rectifier circuit. I appreciated Anindo Ghosh's response to that question with its explanations and recommendations for getting the best result if my main purpose was to build a good rectifier.

Anindo was correct, however, when he inferred that I want to use the light from the LEDs in the bridge rather than its d.c. output. So....I have a couple of follow-up questions:

for the current-limiting resistance needed to protect the LEDs, should I put a single resistor between one leg of the generator output and its bridge connection (with the resistor value calculated from the voltage drop across the sum of the forward voltages divided by the sum of the forward currents of all 4 LEDs), or should I put a resistor between each of the 4 LEDs, all with the same value (calculated from the voltage drop across a single LED divided by the forward current of a single LED)?
would the LEDs in the bridge produce light without a d.c. load (e.g. another LED or a resistor) on the bridge?


texts:
Is it possible to implement MPPT for a load whose operating voltage is nearly equal to the solar panel's open circuit voltage.

edit: Is it possible with buck converter alone?


texts:
Just wanting to clarify my understanding of ESR here, because I'm not fully sure if it should be modeled the way I would think to model series resistance. Or if it's more complex than that.

Basically the question comes down to is there any reason why one wouldn't place a ceramic capacitor in parallel with an electrolytic cap to drastically reduce the total ESR.

This is going off the assumptions that:

The total ESR of two capacitors placed in series is modeled by the parallel resistance equation $$\dfrac{1}{\frac{1}{R_1} + \frac{1}{R_2}}$$
Both capacitors are rated for the appropriate voltage.
Ceramic capacitors have << ESR than electrolytic capacitors

So the ceramic capacitor would have a negligible effect on the total capacitance, but be the primary determinant in the total ESR. (values are 2200uF electrolytic, 1uF ceramic, 24V)

The reason that I ask this is I am trying to quickly discharge some capacitors into an LED for 1us and my understanding was the rate of discharge was directly proportional to the ESR (plus whatever is going on in the circuit that is connected)


texts:
AFAIU, PWM works as follows:

According to the value of the counter in the microcontroller, a square wave is generated at a designated output pin of the \$\mu C\$. The duty cycle of this square wave is determined by the previously set compare value of the counter and the current value of the counter.

So, at a given time, if the counter is, say, higher than the compare value, the square wave at the designated output will be at high voltage (\$V_H\$). Similarly, if counter is lower than the compare value, the square wave at the designated output will be at low voltage (\$V_L\$).

I have heard that we are able to simulate analog output using PWM. For example, if the duty cycle of the output square wave is, say 60%, then AFAIK, we treat the output signal as if it is \$ (V_H - V_L) * duty cycle\$ for the whole duration of that PWM period.

But how is this possible? In reality, a 60% duty cycle means that the output signal is fully at \$ V_H \$ for 60% of the PWM period and it is fully at \$ V_L \$ at the remaining 40% of the PWM period.

How are we able to treat the output signal as if it is \$ (V_H - V_L) * duty cycle \$ for the whole of the period?


texts: How can you recieve a 6 GHz signal with only 64MS/s ADC?

texts:
The Ettus Research Software Defined Radio B210 has a range of 70 MHz - 6 GHz, a Bandwidth of 56 MHz and its maximum ADC rate is 61.44 MS/s. Doesn't Nyquist theorem state that the sampling rate should be 2*Fmax, where Fmax here is 6 GHz ?

EDIT: the board uses Analog Devices AD9361 RFIC


texts: What makes OSL (Open Short Load) calibrators so expensive/sophisticated?

texts:
An OSL that can go up to the GHZ can costs several hundreds if not thousands of dollars, what makes them so special?
My theory is that a load involves some sort of special resistor and mantaining a 50ohm load into the GHz might not be so easy, same thing with the short, a piece of wire is a transmission line at those frequencies, inductance/capacitance can have a big effect. But does that justify the huge cost?
More importantly, what about an open? What makes an open from the calibrator so different from just leaving the line unterminated? an open is an open is an open, so why do we need it?
What are the technicalities behind a good OSL calibrator that an amateur with a soldering Iron, some N Type connectors and some RF SMD resistors can't do?


texts: Can I replace a relay with (e.g.) a transistor in this resistor ladder circuit?

texts:
I'm controlling a Sony car stereo from my car steering wheel remote via an ATMEGA328, based on this project.

It works by keeping the ATMEGA's digital pins in input mode while idle, and setting a single digital pin to output a 0 to activate a corresponding remote function via a resistance ladder. According to the original project, this

  works because the Sony unit reads the remote control resistance using a voltage less than the [...] power supply

(I measured this at ~3.3v). My circuit works fine while powered from 5v, but when I turn off the car's ignition (which removes power from the circuit) and the stereo is still on, the controls on the stereo itself stop working, and sometimes the stereo receives erroneous commands.

To work around this, I put a relay between the ATMEGA circuit and the stereo remote input, powered by the same source that powers the circuit. So when the power is cut, the circuit is physically disconnected. This works fine.

simulate this circuit – Schematic created using CircuitLab

What I'm wondering is if I can remove the relay and replace it with something less bulky that will give me a similar high impedance (relative to 0v) when power is removed from the circuit, and when power is applied have a minimal impact on the voltage across the remote control input.

I have a mixed bag of transistors and other miscellaneous components lying around; is there a simple solid-state circuit that will achieve what I'm looking for? What sort of transistor is best suited to this application?

EDIT:

Some more information: Remote control input is at ~3.3v at open circuit. Depending on which output is selected, it will come down to between 0 and 2.3v.

I guess I'm picturing something like this:

When power is off, Q1 won't be powered and so C-E will effectively be open-circuit, which is what I need.
When powered and idle, I don't really care if Q1 is "on" or not.
When powered and an output goes active, B will be pulled down towards 0V via the resistor ladder, \$V_{BE}\$ will be sufficient to turn on the transistor and \$V_{CE}\$ will therefore go to 0V, and the correct resistance/voltage will be presented at the remote control input.

What I don't know is if this setup will work in reality, will having the transistor in the circuit affect the resulting voltages to the input (or stop it working altogether), and if it will work, what characteristics I should be looking for in Q1 and R9 (assuming it's going to work the way I want, I guess the voltage across R9 and B-E will vary from 2.7v to 5v depending on which output is selected). Is there a minimum collector current required to get full saturation? Or am I just way off target altogether?

simulate this circuit


texts: Circuit design - usage of BOOT0 on STM32G474

texts:
I'm involved in a collaboration to develop a motor driver circuit based on the 48 pin STM32G474 microcontroller. I'm using TIM8 timers to drive the PWM of a DRV8323RH chip.

My question is about the use of BOOT0 pin. My understanding of the BOOT0 pin is that when the BOOT0 pin is at a low level, the STM32G4 microcontroller boots from the User Flash memory. When the BOOT0 pin is at a high level, the nBOOT1 bit determines the boot mode.

Where I'm confused is that in a previous incarnation of the PCB we tied BOOT0 to ground, and programmed STM32G474 we use an st-link2 system, through the TCK and TMS pins. In this incarnation of the board we would prefer to use PB8-BOOT0 to send PWM to the driver chip.

If I am programming using the st-link2 system as before, will I still be able to program the STM32G4 if I tie the PB8-BOOT0 to PWM of the driver?

thank you.


texts: Altium automatically adds footprint to new library component. How to solve it?

texts:
I have a problem with Altium and i couldn't solve it.

When I add new symbol to my integrated library, by default it has 6 footprints and the symbol designator and comment is same every time (not Altium's default) and I should delete them every time to add my footprint and symbol. I want to change it back to the default (schematic symbol with no footprint, NO comment and default designator "*") please help me solve this problem.


texts: Trying to figure out how to solar power an embedded device

texts:
I have an Arndale octa board which itself needs 5V 3A power supply.  Then I have four (4x) DC 5V motors and a 5V servo, and a number of other peripheals.  So I think 5V 5A is safe to assume?

I want to power all of this with Solar, which if there's not enough light I will switch to a backup battery (that the solar also charges, during idle time)

I tried doing some research but I'm just so confused.  I know I will need like 12 or 24V rechargable battery and a buck regulator, perhaps a board that regulates between solar/battery and such, and solar panels.   But I am really in over my head trying to figure out the pieces.  Can someone please help point me to some good products to do what I want?


texts: How to get the correct resistance and electrical intensity for this circuit?

texts:
I have a resonant parallel circuit, uing an electric capacitor, rectifier, oscillator and 2 coils.

I want to charge a cell phone wirelessly for a project at my school, so I researched this.

Generally, a cell phone is charged with 3.0 - 4.0 volts. So, how do I calculate how many ohms should my resistance be and the amps of my electric current?
The formula is: V = IR, then

4 = IR, but I have two variables, then, how do I get it?

The diagram is this:


texts: Does not trigger an interrupt DMA when reading SPI. Last byte transaction not coming

texts:
I use DMA for reading with SPI flash using USART. MCU - master, flash - slave. I read 1029 bytes per transaction. Exchange algorithm:

I activate the flash (CS = 0)
I configure the DMA channel to receive 1029 bytes. Allow IRQ_RX read interrupt
I configure another DMA channel to transmit 1029 bytes. Allow IRQ_TX interrupt, enable channel-at this time send / receive
In the IRQ_TX handler, clear the interrupt enable flag
In the IRQ_RX handler, I clear the interrupt enable flag + deactivate the flash (CS = 1)

It works. But very rarely there is an error when I send 1029 bytes, but only 1028 is received. In the debugger, I see that the DMA counter sent bytes is 0 (sent 1029), and the counter read is 1 (up to 1028). Since DMA did not receive the last byte, RX interrupt does not occur, and I can not enter the RX interrupt handler. The interrupt handler TX is called, that is, 1029 bytes are accurately sent. Error flags are zero. This error occurs rarely. Why don't I get the last byte, what could be wrong?

MCU - F2MC-16FX MB96600 Series. IDE Softune Workbench

void USART_start_DMA_read(void)
{
    /* correct size_pic and address */

    //INIT DMA FOR READ
    if(UART2_SSR2_RDRF==0)
    UART2_ESIR2_RDRF=0; //clear RDRF -  Reception data register full

    DSR_DTE2 = 0x0; //Clear possible DMA 2 request
    DER_EN2 = 0x0; //DMA 2 channel disable
    DISEL2 = _IRQ_LINR2; //< LIN USART 2 RX
    DCT2 = 1029; //how much to read
    IOA2 = (unsigned long)&UART2_RDR2;
    DMACS2 = 0x10; //no IOA update, BAP update, byte transfer, IOA -> BAP
    BAPH2 = (unsigned long) &graph_buf[beg_byte] >> 16;
    BAPM2 = (unsigned long) &graph_buf[beg_byte] >> 8;
    BAPL2 = (unsigned long) &graph_buf[beg_byte] & 0xFF;
    DER_EN2 = 1; // DMA 2 channel enable

    UART2_SSR2_RIE = 1; //enable irq RX - at this point the channel is ready to receive bytes

    FLASH_CS = FLASH_ON; //enable flash

    //INIT DMA FOR SEND
    if(UART2_SSR2_TDRE==0)
        UART2_ESIR2_TDRE=0; //clear TDRF -  Transmit data register full

    DSR_DTE3 = 0x0; //Clear possible DMA 3 request
    DER_EN3 = 0x0; //DMA 3 channel disable
    DISEL3 = _IRQ_LINT2; //< LIN USART 2 TX
    DCT3 = DCT2; //how much to send
    IOA3 = (unsigned long)&UART2_TDR2;
    DMACS3 = 0x12; //no IOA update, BAP update, byte transfer, BAP -> IOA
    BAPH3 = (unsigned long) &read_flash_cmd[0] >> 16;
    BAPM3 = (unsigned long) &read_flash_cmd[0] >> 8;
    BAPL3 = ((unsigned long) &read_flash_cmd[0] & 0xFF);
    DER_EN3 = 1; // DMA 3 channel enable

    UART2_SSR2_TIE = 1; //enable irq TX - at this point the transmission / reading starts
}

void IRQ_USART2_TX()
{
    //after transferring 1029 bytes
    UART2_SSR2_TIE=0; //disable irq TX
    DSR_DTE3 = 0x0; //clear DMA channel request
    __wait_nop();
    __wait_nop();
    __wait_nop();
    __wait_nop();
    __wait_nop();
}

void IRQ_USART2_RX(void)
{
    //after reading 1029 bytes
    FLASH_CS = FLASH_OFF; //disable flash
    UART2_SSR2_RIE = 0; //disable irq RX
    DSR_DTE2 = 0x0; //clear DMA channel request

    //if not the entire object is read - read the following data block
    if(size_pic)
    {
        USART_start_DMA_read();
    }
}

Updated.
Failure occurs if I run the firmware through the debugger. If I run without debugger, everything works without failures. What do you think, can the debugger affect the work?


texts: What is the name of this component in logic board?

texts: This picture is for my tablet logic board, there are two of this component on the board, one is kinda rusty so I removed it and wanted to replace it but then I don't know the name of it. Can anyone can? thanks in advance


texts:
I have done a few projects on Arduinos. Now I want to step up my embedded skills.

I have found this SoC with embedded Linux and video encoding/decoding capabilities. I am interested on running OpenCV on it.

My question is how do I play around with something like this?

Do I have to make a PCB using Eagle? Do I have to buy an external programmer? Maybe use a converter PCB so I have DIP interface?

I know I will probably get downvoted for this question, but I want to buy it and start playing with it as soon as possible. That's why I ask.


texts: is the drawn diagram right for detecting a sequence of three or more 1's?

texts:
i saw this diagram in my textbook for the problem :

Suppose we wish to design a circuit that detects a sequence of three or more consecutive 1’s in a string of bits coming through an input line (i.e., the input is a serial bit
stream)

this is the diagram the book suggests .

si means we have read i consecutive 1's from the input (s3 means 3 or more consecutive 1's) and s0 is the start state.

my problem is when we are in state s2 and we read a 1 in input the output is still 0 while it should change to 1.

and also when we are in state s3 and we read a 0 the output is still 1 while it should change to 0.

my mealy implementation (excluding some arcs) is

here we do not have the above problems .

i know the first one is a Moore implementation while the second one is a Mealy implementation .

BUT shouldn't they do the same thing .


texts: Is it possible to connect ballast in parallel with AC source without resistor?

texts: I am working on a project that will implement automatic power factor correction for inductive loads. I would like to use the ballast from a fluorescent lamp as my test load for this project. Is it possible to connect such a ballast directly across the AC line, or do I need to use a resistor to limit the current?


texts: why the 3 stage differential opamp not worked

texts:
i did the following in simulation its work.
but in practically, i cannot able to get a amplified output.
i use ic741 as a op-amp 5v input for opamp and bridge power supply... i get always 1.77v in my output side for all kind of input.
give me a suggestion.


texts: LiPo/Li-Ion Cells in series max end-to-end voltage

texts:
I have wondered how many cells can be connected in series before issues may arise. I also wonder what specifications on the tech data sheet would allow you to decide which batteries are best for high voltages series?

My current understanding is that even though the end to end voltage may be high in a series of cells the voltage across a single cell will only be that cells voltage?

Other thoughts about the eventual mode of failure? Insulation? Shorting?


texts: Will an RF modulator provide NTSC System M spec video from a DVD player?

texts:
I've been attempting to recreate the effect of an old NTSC television broadcast lately with the use of DVDs. The DVD-Video spec allows for up to 720 x 480 pixels at a display rate of 29.97 frames per second, interlaced.

My DVD player is outputting composite video to an RF modulator which is then connected to my TV and the signal is demodulated by the receiver, effectively simulating the NTSC transmission model.

What I'm wondering is if RF modulators output NTSC System M spec video for everything you feed it, allowing for a maximum video bandwidth of 4.2 MHz or about 330 lines of horizontal resolution (440 x 486 from a digital perspective), or if it's converting the composite video signal to RF however it sees fit and the resulting image will look more like 540 line DVD?

Any help would be greatly appreciated.


texts:
I am designing a mobile robot which needs to re-charge in a docking station, but I'm having difficulty deciding what to do about the connector. I have two choices: design and make our own connector, or use an off-the-shelf connector.

The connector needs to carry 30V at 3A, and must survive at least a few hundred thousand mating cycles. Also, since it's going to be mated by a clumsy robot, it needs to be physically robust and easily mate even under non-ideal circumstances. The robot weighs only about 2kg, and so cannot produce enough force to mate a mains connector.

Ideally, I would like to design my own connector, so that I can design it to mate easily. But since connectors are a major source of unreliability, I feel this might be a bad idea.

Added: Existing docking connectors for most products tend to be small, fiddly, rated for less than 3A, and less than 10k mating cycles. Even standard 2.5mm pin DC jacks are only rated for 5k cycles. Larger connectors like mains plugs have quite a high insertion force, and don't seem to state their mating cycle rating.

Questions:

If I design my own connector, what should I do to ensure several hundred thousand mating cycles?

Are there any off-the-shelf connectors which might do the job?


texts:
I have a 230v to 110v transformer which I use to power some equipment. I saw on the internet that some power transformers need a soft start circuit.
The power of my transformer is 200VA.
On the internet is specified that only transformers with a power over 300VA require a soft start circuit.
I also read on the internet that if I connect the transformer to 230v there is a high current which goes through the primary winding for a short period of time.

My questions are:
Do I need a soft start for my 200va transformer?

What happens if I connect some equipment (for example a soldering station or an oscilloscope) to the secondary of the 200va and after that I connect the transformer to 230v?

Is possible to appear in the secondary a voltage bigger than 110v which can damage my equipment?


texts: Resistor circuit to correct impedance matching and attenuate signal by 10 decibels

texts:
I've got a Line Out on my amplifier with 100-600 ohm impedance (avg. 350). I have it connected to an effects pedal that has a 1M ohm input.
Right now the signal is clipping from the amplifier and I would like to attenuate that with a resistor only configuration, and simultaneously adjust the impedance each side sees. I'm looking for just 10dB of attenuation, or 1/3rd the volts.
Fix:

Amp needs to see 10K ohms on the other side instead of 1M ohms.
Pedal usually expects 1K ohms on the other side instead of 100-600 ohms (avg 350).
1/3 volts at the pedal inputs is desired attenuation.
All using unbalanced connections.

With this configuration below, the amp now sees 10.3k ohms and the pedal now sees 1k ohms. And the volts is 3.33V instead of 10.
Any problems that you see? I tried T and Pi configurations and they didn't work. By adding the resistor at the bottom it all seems to compute. Not sure if I did this right.


texts: Why does two-BJT transistor-based capacitance multiplier show bad performance

texts:
I'm trying to understand why two-BJT transistor-based capacitance multiplier shows bad performance.
The circuit (note that capacitance multipliers are bi-polar):

Below are time output for usual RC circuit (in green), same RC parameters powered by BJT multiplier (in blue), same powered by op amp multiplier (in red):

Basic RC elements in all above circuits are 10μF capacitor and 10k resistor.
Red graph was taken from the top pin of R6, blue one from that of R32, green one from that of R1, respectively.
Please ignore the circuit in the bottom left corner, it's unrelated.
Emulated capacitor in op amp curcuit discharged from 10V to 1V over ~2200 secs (36 min), emulated capacitor in BJT circuit did so over ~11 secs, natural one did so over 0.22 secs.
Emulation is apparently correct both in BJT and op amp performance (discharge slopes are exponential in their visible shapes).
Leverages in both emulations are resistor pairs of 10 and 100k Ohms (R3-R4 with R2-R5, R24-R30 with R23-R31 respectively).
Modifying hFE values of the transistors and their emitter resistors gives little effect.
Note that one can enlarge emulated capacitor in both cases by decreasing R3-R4 (R24-R30) and by increasing R2-R5 (R23-R31).
But why do hFE values matter so little here (200 times worse than op amp in any way)?
Did I miss anything?


texts: I often read the term pseudo-differential when looking for ADCs. I know common differential means that the ADC measures a difference between two of its pins (AN+, AN-). But what is the difference to pseudo-differential?


texts: Level shifting 5V to 3.3V - can I just use a zener diode?

texts:
simulate this circuit – Schematic created using CircuitLab

My problem is the ATmega328 is running at 5V. I know I need a bidirectional level shifter. However don't really want to spend much more money on this if I can. I don't want to blow up an expensive amplifier as well. Most expensive IC I've ever bought.

The D2 pin would output 5V but I thought zener diodes are commonly used for over voltage protection. So why I can't just use this diode to clamp it down to 3.3v? I know I need bidirectional level shifting  but wouldn't the voltage be clamped to 3.3v either way?


texts: What products which support 110V/60Hz you can use in Europe with a power converter to 110V/50Hz

texts:
I was wondering what products which only support 110V/60Hz you can use in Europe with a power converter from 230V/50Hz to 110V/50Hz.
In what product the different frequency will be a problem ? and in what products the different frequency will not be a problem?

P.S
I am thinking about this product:
https://www.oxo.com/oxo-on-9-cup-coffee-maker


texts: Using a residual current device when there is an isolation transformer

texts:
In a system, currently there is no circuit breaker and RCD, but there is an isolation transformer as in the diagram below:

simulate this circuit – Schematic created using CircuitLab

As you see the transformer has no earth wire connection.

What would be the safety approach for the secondary side? Can we say that the transformer already isolates the earth so an RCD is not necessary both at secondary and primary sides? Or is there still some benefit to have an RCD before the isolation transformer.

I mean if the secondary in above diagram is earthed accidentally the isolation will be defeated; in that case would the RCD in primary side still trip if someone touches the live chassis of the load?


texts: How can I design my PCB to mount to a wood panel without wasting a lot of space on screw holes?

texts:
I'm designing a small board, with these quick disconnect tabs along the edges.  The board will be mounted to a non-conductive surface.  I had initially planned to use screws at the corners, but the shape of the components means this results in a significant increase of footprint, and I'd like to keep costs down.  My hope is to avoid margins, such as those in this (trivial) example.

Is there a more efficient way to mount this board, in terms of board area?  I've considered soldering on ring connectors that will stick out the corners, and putting screws through the rings.  That seems weak and
unprofessional, though.  Slot mounting is unfavorable, since the board will be mounted on a flat surface with space around it.

Related questions:
Mounting a PCB in an Extruded Aluminum case
Mounting my PCB project


texts: How does the component "alarm boost three pin inductor" make a piezo buzzer louder?

texts:
I have a small circuit working on 2xAA batteries (3V) with an MCU and a buzzer for alarm sound.
I've already successfully used an active buzzer (with build-in driver oscillator) drived by an NPN transistor in on-off, and it worked fine.
Now I've changed the board and its case, and I need to change the buzzer to a piezo one of this kind:

I know that I need to drive it with a waveform because it doesn't have the driver circuit and all the stuff, so I started using the circuit on the right, which worked, but was not very loud, so I started document how to make it louder.
I'm already feeding the BJT with a PWM with duty cycle 50% around the resonant frequency of the buzzer, so  I can't do better about the frequency. Since the maximum peak to peak voltage in the datasheet is 30V I tried to use a 25V source (only for the BJT circuit, not the digital part), and in fact it becomes significatly louder, so basically the goal is to step-up the voltage around the buzzer.
Since the piezo is basically like a capacitor, putting an inductor instead of R2 makes a resonator and makes it louder, but since my power supply is very low compared with the 30V maximum of the buzzer, that's still too little..  I want more :)
One option is to use an H bridge for doubling up the peak to peak voltage, but since the starting voltage is low, the buzzer will be louder but not as much as I wish. Another option is to insert in the board a circuit to step-up the supply of that part. I suppose it would work, but finding something simpler would be better.
While I was searching, I took a look at a small device I had at home which makes a loud noise.  I opened it and I realized that was using a buzzer very similar (bigger in radius which makes it work at a different frequency, but that's not the point) and a circuit very similar to the one posted above, but instead of R2 there's an inductor-like thing. I started googling and I'm pretty sure the part is this, connected as in this figure:

Where two pins are connected as R2, and the third (don't know which of the three) is connected to Vcc.
edit: I've inserted the circuit because the previous sentence was not correct/clear. Also I would say that in this circuit I actually don't know what Vin is (square wave or something else).
I found the component on alibaba/aliexpress from China, and there it's always called something like "alarm boost three pin inductor" (if you try to search on alibaba those exact words you'll find a lot of them).
These are my questions:

What is that component that seems (based on the name) specifically made for this purpose?
Why does it make the buzzer make so much more noise with it (also the circuit that I saw the component on works at 3V, like mine, so no difference there)?
I managed find that component only on alibaba/aliexpress, possibly I can't find it on RS-Components/Farnell/Mouser/etc. because I don't know what to search for and, eventually, how to dimension it.
Other suggestions about how to make the buzzer louder?

The goal is to understand what's going on there, eventually understand how to dimension it, and find a couple of those for try this way.
edit: After the @marko answer, I understood that the mysterious component is an autotransformer, is it correct to say that it's like a transformer with two pins connected? If it is correct, the circuit I saw should be one of the three cases forward, possible? Which one could it be?

Say that my Vcc is 2.5V and I want todrive the buzzer with 25V (so x10). My Vin is a square wave at whatever frequency and duty cicle are needed (the resonant frequency of the buzzer is 6.5kHz so I guess that's the best choice), how can I broadly calculate the values of the autotransformer? Could the stepped-up voltage given by the inductor damage the source power? Would be better to put a diode before the Vcc?


texts: Why have a PID controller for a DC servo motor?

texts:
Let's say i have a servo motor, and i send it an angle represented as a PWM. How can this system ever overshoot?

Will it overshoot when I try to increase the speed?

The steady state error can of cause be a reality, if something is holding the motor back.

I'm just a little confused of why i should use a PID or any other controller to the system, when i have feed back AND can send it a position

Br.


texts: Designing for Low Cost China Manufacturing

texts:
I have designed a few boards on a consulting basis. Some of them have been manufactured in China in +10k unit volumes. One of the complains I have gotten from my clients is my boards can be a bit expensive. (These clients have no real experience with electronics, so I take it with a grain of salt). This is even after taking short cuts and "simplification". This made me consider, I have heard some ST parts, unbranded SMPS controllers etc. are dirt cheap in China.

When I put an 80 cent ATTiny micro-controller, or a TI LiPo charger on a board, even if it is one of the cheapest chips in its category on distributors like Digikey, is it still really cheap in China?

Short of having a relationship with local Chinese manufactures to ask what chips, capacitors, SMPS chips they commonly use, is there a better way to gauge true BOM cost once a board moves from engineering to mass production with respect to other options?

Any advice on how other small scale US designers handle this issue?

I should add, I'm not usually involved in the manufacturing, I just pass off a finished design to someone running a Kickstarter etc. Then called back when/if they have issues.


texts: Does the 65C02S processor Reset Sequence require that its data pins be connected during reset?

texts:
I have a 65C02S processor wired up and the address and data pins connected to an Arduino Mega so that I can print the state of the data bus and address bus for testing purposes. The 65C02 datasheet states that the RESB input should be held low for 2 clock cycles to initialize the microprocessor and start program execution. As part of the reset, the processor goes through an initialization sequence lasting seven clock cycles. Upon completion of the reset sequence, the program counter is loaded with the reset vector from locations FFFC (low byte) and FFFD (high byte). This is the start location for program control.

I expect to see these two addresses on the address bus after I have advanced the processor through its 7 clock cycles, but I don't see them. My question is: do the data pins (D0-D7) need to supply the processor with an instruction during the reset sequence to ensure that the processor puts the address of the reset vector on the address bus, or is the processor kaput? At the moment, the data pins are connected to the Arduino which is only reading the state of the pins.


texts: Switching polarity of rectified AC power with a microcontroller

texts:
I am trying to create a circuit that will allow me to control the polarity of the current flowing through a coil in order to attract or repel a magnet.  I would like to use two MOSFETs in series since activating a single MOSFET will half wave rectify the current by flowing through the body diode of the other MOSFET.

I have attached a simplified version of what I have envisioned.  A microcontroller (not shown) would control through the Opto-coupler.  The circuit works fine until the  bottom MOSFET is activated.  When that happens, on the negative AC power cycle the power flows through the bottom MOSFET, takes a least path of resistance shortcut at the problem point to the bridge rectifier and back to it's home in 110VAC.  Poof.

In theory, a battery could operate this circuit fine, but my I would like to design this circuit so it works completely on AC power.  How can I control these MOSFETS without shorting the circuit?

simulate this circuit – Schematic created using CircuitLab


texts: Inerfacing switch & led with any controller

texts:
I am trying to interface switch and led. I want to write a program in which if I press and release the switch led should glow and if I again press the switch led should turn off. I am not able to write logic for it as I am newbie to embedded system. Can anyone just help me writing the logic for it.?
Thanks.

This is my code of turning on and off led using switch
CODE

int main(void)
 {
    DDRC |= (1<<PC0); //Makes first pin of PORTC as Output
    DDRD &= ~(1<<PD0);//Makes firs pin of PORTD as Input

    while(1) //infinite loop
    {
        if(PIND & (1<<PD0) == 1) //If switch is pressed
        {
            PORTC |= (1<<PC0); //Turns ON LED
            _delay_ms(3000); //3 second delay
            PORTC &= ~(1<<PC0); //Turns OFF LED
        }
    }
}


texts:
I want to implement a driver circuit for piezo actuators for a positioning system. For this, I require a high-voltage, low-current output, similar to the one discussed here which features a circuit taken from here.
Concerning that circuit, I don't see how it can be used for a positioning system...The piezo elements can be "extended" and "contracted" by applying a higher and lower voltage across it, respectively. Where does this voltage control across the piezo happen in the circuit?
What I (ideally) want for myself is a way to supply the piezo with 0VDC to 75VDC depending on an analog DC input signal between 0V and 5V (from an IO-card).
EDIT: I don't know exactly which piezo was intended for the above circuit, however, my piezos are the PK2FMP1 from Thorlabs


texts: How big variables are stored in RAM memory?

texts:
I've just made a simple RAM memory in Minecraft (with redstone), with 4 bits for the address and 4 bits stored in each cell. Our next goal is to store different kinds of variables in it and to process them differently.

We are not engineers, so we really know nothing, but we have already made some quite complex things and we think we can do this. The problem is that we can't figure out how to store variables of more bits than can be stored in a single cell. I'll give an example.

Think of a 16-bit variable. We thought that there would be no sense in creating such big cells, so we decided to store that data by storing 4 bits in each cell. But that's not enough, we have to relate those 4 cells to each other. So we thought that we had to create 8-bit cells, with 4 bits of content and 4 bits to store the address where the next 4 bits of the variable are stored. However, 4 bits of address is nothing for a RAM memory, we can't store anything there. So we would need at least 8 bits for the address. 4 bits of content also seams quite low, and we also need at least another 4 bits to store the type of the variable.

Well, finally we thought that that technique was absurd and that it wouldn't be done like that in real life. And we don't know how to do it now. I've searched on the web about how RAM memory works and the few pages that I've found were too complex for our needs. Could someone please explain to us how this is done in real life and how we can apply it in redstone?


texts: How to find the current derivative(di/dt) at t = 0+ in the first loop?


texts: Why resonant charging produce "no current immediately after discharge"?

texts:
It's me again, still reading AoE 3rd. On page 40, footnote 35, the author writes:

  Resonant charging is used for the high-voltage supply in flashlamps
  and stroboscopes, with the advantages of (a) ......, and (b) no
  current immediately after discharge (see waveforms), thus permitting
  the flashlamp to “quench” after each flash.

The waveform looks like this:

So why can resonant charging produce "no current immediately after discharge" but resistive charging doesn't? And I didn't see a current waveform.


texts: High-density, light multiconductor cable: sources/suppliers/manufacturers?

texts:
I'm looking for a multiconductor cable with 30-40 conductors, optimized for flexibility and small outer diameter. Unlike say, Litz wire, most wires will carry an independent (microvolt) signal. The application is to transmit data from a tethered, mobile data acquisition device.

The multiconductor products carried by the major electronics suppliers tend to be larger diameter; for instance, while this one is not bad at 7.4 mm OD for 36 conductors, I'd like something smaller still. For this cable, the individual conductors are 28 AWG, but I'd be happy for them to be 30 or smaller.

Where might I find such a thing?


texts: Is it OK to allow to more than 16mA (say 1A) to flow through Raspberry Pi GND pin?

texts:
I am fairly new to electronics and I'm designing a circuit which has two electromagnets (in my diagram I've used bulb symbols as I couldn't figure out how to represent the resistance of the component using the inductor symbol), but the current flowing from the power pack to the Raspberry Pi's ground is more than 16mA (which I gather is the max current for Raspberry Pi's GPIO pins to output). Is this OK, or will this current damage the Raspberry Pi's GND pins? I am aware there may be some other errors in my circuit; any help would be much appreciated!
Here's the circuit:

simulate this circuit – Schematic created using CircuitLab


texts: Is there a material that I could use to generate cap touch presses?

texts:
I want to automate some testing that uses captouch as the interface for the human user. I would love to use an Arduino or similar's GPIO to create the equivalent press and release events from a finger. Is there some material that can be used here such that it would cause a press event when I set the GPIO to high? I would like to avoid any mechanical solutions that involve moving things. Ideally, I would tape the material onto the place where the button is and run my fake human code on the Arduino.

Had a hard time wording that, hope it makes sense. Also, I'm pretty ignorant with the electronics for a captouch system given that I'm a software guy...be gentle :pray: