DIY LED Stroboscope to Check Turntable Speed

RE: DIY LED Stroboscope to Check Turntable Speed

colporteur — Wed, 01 Apr 2020 23:03:47 GMT

The theory to support why projects like this works is amazing. My career in electronics started in the early 80's. Why things worked was just as important as how they worked. Great article!

RE: DIY LED Stroboscope to Check Turntable Speed

neuromodulator — Mon, 30 Mar 2020 23:29:53 GMT

Lowering the duty cycle can make edges sharper but also reduce the illumination. To compensate that, what I've done is to overdrive LEDs, at very short pulses you can multiply its rated current a few times. Datasheets usually don't specify how much you can overdrive the LEDs so you may end up needing some destructive testing to figure out the LED limits.

RE: DIY LED Stroboscope to Check Turntable Speed

phoenixcomm — Mon, 30 Mar 2020 23:04:27 GMT

[mention:acaf6a9338de4eef8f6717d5561ed01d:e9ed411860ed4f2ba0265705b8793d05] Jan I write in ANSII C 80 -90% of the time. And you must obey dah rules!

#define PWM_OUTPUT 9
#define FREQ_DIV 10000
void setup()
{
pinMode(PWM_OUTPUT, OUTPUT);//Pwm pin as Output line is good set the pin,
TCCR1A=_BV(COM1A1)|_BV(COM1B1);//Non-inverted Mode this could be a #define;
TCCR1B=_BV(WGM13)|_BV(CS11);//Prescalar 8 same here
ICR1 = FREQ_DIV; // ?? Then, in line 12, I divide that clock again, by setting the timer's counter. The result is a 100 Hz signal. splean please.
OCR1A = int (FREQ_DIV/2); // duty cycle could be a #define OCR!A ubt(ICR1/2)
}

normaly in C main() { // is where you start

if( setup() != FAIL ) { // is where set up timers address etc and serial and network connections, may in fact be a series of functions.

if( initalize() != FAiL { set it all to a known condition

do {

body stuff } ( xx != RUN );

} else

return(); }

RE: DIY LED Stroboscope to Check Turntable Speed

dubbie — Mon, 30 Mar 2020 14:56:30 GMT

A nice project and good to see two different controllers used. Do you know what the allowed variation for turntable speed is before it becomes noticeable in the audio output of the turn table?

Dubbie

RE: DIY LED Stroboscope to Check Turntable Speed

DAB — Sun, 29 Mar 2020 17:44:03 GMT

Nice project Jan.

DAB

RE: DIY LED Stroboscope to Check Turntable Speed

glennvanderveer — Sun, 29 Mar 2020 15:29:34 GMT

Very cool. I kind of wish my turntable had a speed control now...

RE: DIY LED Stroboscope to Check Turntable Speed

dougw — Sun, 29 Mar 2020 15:17:29 GMT

Cool project.

Maybe if you create a disk with the right number of marks to synchronize with your camera shutter rate or frame rate, it would be similar to the strobe effect.

Incidentally, I think there is a typo - it was fluorescent bulbs that flickered at the mains frequency. Incandescent bulbs don't flicker much because of their thermal time constant.