Recent Posts

1

General Technical Chat / Re: Relay trigger when voltage above 13v

« Last post by Ian.M on Today at 02:44:07 am »

TL431, driving the base of a PNP transistor to switch the supply to the relay.  You'll need appropriate base resistors, an anti-parallel diode across the relay coil, and possibly a high value feedback resistor from the collector of the PNP to the TL431 REF pin to add a little hysteresis.  Make the feedback resistor much lower, and once triggered it will latch on, till you momentarily either remove the supply, or ground the REF pin.

2

Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by floobydust on Today at 02:43:37 am »

I would check the VFD's getter has not gone white due to air ingress in the tube.
A '518 output short to another or to ground would heat up the IC and possibly damage it. Look for any solder bridges or just beep it out checking continuity. You can do this with the display in, also ohmmeter the pins to ground, look for shorts.

3

Repair / Re: Mig welder wire feeder controller board not working

« Last post by xavier60 on Today at 02:25:24 am »

A little off topic but wire feed related. Since repairing a no wire feed problem with my brother's WIA 250i, it now will stop feeding if an arc doesn't strike within a second of pulling the trigger. Seems to be a feature that has been activated somehow, but no mention of it in the manual. Not a problem in practice.

4

Beginners / Re: 555 driver and Transformer questions

« Last post by DanMann on Today at 02:24:23 am »

to confirm, I attempting to use this power supply for its original intended purpose.

I do not want to replace the power supply as it passes all checks I  am looking to maintain as much of the original parts as possible, such as the vacuum tube rectifier.

I am trying to replace the mechanical vibrator (interrupter) which is the weak link and is shown in the purple box in the diagram I posted in my previous post. 










 

5

Test Equipment / Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)

« Last post by Kean on Today at 02:21:57 am »

How does this look to you?

I added a plastic washer under that screw on mine.

6

Microcontrollers / Signal Edge (high and low) Validation and counter - sharing C++/Arduino code

« Last post by Andre Laloni on Today at 02:21:40 am »

I recently wrote a simple piece of code that could be helpful to others. Note that the code here needs a little customization to be used. I posted a generic version of it to facilitate such customization. Pretty self explanatory, however, please ask questions if needed. Hopefully it helps.
Best
AL

Code: [Select]


//set pins
const int pinOne = 2; //
const int pinTwo = 3; //
.
.
.
const int pinN = n; // define as many pins needed for as many input signals needed to be validated

//variables
double currentMillis; //the current time in milliseconds (begins count at power on)
unsigned long lastDebounceTime;  //  (miliseconds) the last time the signals were checked
unsigned long debounceDelay;    // (miliseconds) the debounce time

//arrays
#define numSignals N //define array
// INDEX..............................[0].......[1].........[N]............
const int signalPins[numSignals] = {pinOne, pinTwo, pinN,...}; //include  as many pins declared
boolean signalValidation[numSignals]; //validation output (1=valid)
boolean signalState[numSignals];        // current state of the signal
boolean lastSignalState[numSignals];    // previous state of the signal
int highSignalValidationCounter[numSignals]; // signal counter for valid high signals
int lowSignalValidationCounter[numSignals]; // signal counter for valid low signals

void setup() { //system variables initial set values
  lastDebounceTime = 0;
  debounceDelay = 10;//change to suit sensitivity needs
  //arrays initial set values
  for (int i = 0; i < numSignals ; i++) {
    signalValidation[i] = 0; //validation output (1=valid)
    signalState[i] = 0;      // current state of the button
    lastSignalState[i] = 0;  // previous state of the button
    highSignalValidationCounter[i] = 0; // signal counter for valid open or close signals
    lowSignalValidationCounter[i] = 0; // signal counter for valid open or close signals
  }
}

  void loop() {
    currentMillis = millis(); //get the current millis at the beginning of the loop
    signalVal (); //validates input signals
  }



7

Beginners / Signal Edge (high and low) Validation and Counter - sharing Arduino/C++ Code

« Last post by Andre Laloni on Today at 02:19:30 am »

I recently wrote a simple piece of code that could be helpful to others. Note that the code here needs a little customization to be used. I posted a generic version of it to facilitate such customization. Pretty self explanatory, however, please ask questions if needed. Hopefully it helps.
Best
AL

Code: [Select]


//set pins
const int pinOne = 2; //
const int pinTwo = 3; //
.
.
.
const int pinN = n; // define as many pins needed for as many input signals needed to be validated

//variables
double currentMillis; //the current time in milliseconds (begins count at power on)
unsigned long lastDebounceTime;  //  (miliseconds) the last time the signals were checked
unsigned long debounceDelay;    // (miliseconds) the debounce time

//arrays
#define numSignals N //define array
// INDEX..............................[0].......[1].........[N]............
const int signalPins[numSignals] = {pinOne, pinTwo, pinN,...}; //include  as many pins declared
boolean signalValidation[numSignals]; //validation output (1=valid)
boolean signalState[numSignals];        // current state of the signal
boolean lastSignalState[numSignals];    // previous state of the signal
int highSignalValidationCounter[numSignals]; // signal counter for valid high signals
int lowSignalValidationCounter[numSignals]; // signal counter for valid low signals

void setup() { //system variables initial set values
  lastDebounceTime = 0;
  debounceDelay = 10;//change to suit sensitivity needs
  //arrays initial set values
  for (int i = 0; i < numSignals ; i++) {
    signalValidation[i] = 0; //validation output (1=valid)
    signalState[i] = 0;      // current state of the button
    lastSignalState[i] = 0;  // previous state of the button
    highSignalValidationCounter[i] = 0; // signal counter for valid open or close signals
    lowSignalValidationCounter[i] = 0; // signal counter for valid open or close signals
  }
}

  void loop() {
    currentMillis = millis(); //get the current millis at the beginning of the loop
    signalVal (); //validates input signals
  }



8

Repair / Re: Mig welder wire feeder controller board not working

« Last post by coppercone2 on Today at 02:19:01 am »

I imagine  the degree of porosity added by some oil would require x-ray to find, it must be very minor.

Not that I care, but you know, boeing might be using mig welders for airframe repair or something

But I do have the mentality that a non professional will benefit from the best possible conditions because the work you put out without it being basically a trade job might be so marginal in some cases that the extra steps keep it barely in line. If I can get some extra help from essentially a passive system I will take it, I just don't have the time and inclination to always do a practice bead and stuff that a pro would get paid to do

9

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by f4eru on Today at 02:15:16 am »

I measured via visual and electrical methods, so there is no doubt about my measurements.

Pleaae publish your measuremenets.

10

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by thermistor-guy on Today at 02:14:16 am »

...
   it's the same story as my Chinese made trailer, it will almost meet the stated load but there is NO safety margin.

There's a Chinese EE located near me, running a transformer rewinding business. He's from Shanghai. Many years ago, he told me that
Chinese electronics are made to a price, and they will only just meet spec. (if at all).

He went on to say that, unlike US or EU equipment, Chinese-brand equipment will not have any overload capability, not even
short-term overload.