50Hz/60Hz stroboscope - UK Vintage Radio Repair and Restoration Discussion Forum

TonyDuell · 9th Apr 2017, 4:49 pm

Attached (I hope) is a little circuit I made years ago to give 100 or 120 flashes per second on white LEDs, thus acting like a lamp powered from 50Hz or 60Hz mains. I use it for setting the motor speed on floppy disk drives, but I am sure it would also be useful with record turntables. For the former use it gives a very clear pattern (much better than any mains lamp I've used) and the crystal is accurate enough.

It uses a standard 4-pin crystal oscillator module, 3 common 74HCT ICs, a 7805 regulator a couple of transistors (not critical types), 4 white LEDs and some R's and C's. It runs off a 12V or so supply. The 3 position switch is off in the middle, set it one way for 50Hx, the other way for 60Hz.

Stroboscope_50Hz_60Hz.pdf

9th Apr 2017, 4:49 pm	#1
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	50Hz/60Hz stroboscope Attached (I hope) is a little circuit I made years ago to give 100 or 120 flashes per second on white LEDs, thus acting like a lamp powered from 50Hz or 60Hz mains. I use it for setting the motor speed on floppy disk drives, but I am sure it would also be useful with record turntables. For the former use it gives a very clear pattern (much better than any mains lamp I've used) and the crystal is accurate enough. It uses a standard 4-pin crystal oscillator module, 3 common 74HCT ICs, a 7805 regulator a couple of transistors (not critical types), 4 white LEDs and some R's and C's. It runs off a 12V or so supply. The 3 position switch is off in the middle, set it one way for 50Hx, the other way for 60Hz. Stroboscope_50Hz_60Hz.pdf