I needed to measure a turntable's number of revolutions per minute, but didn't have any incandescent lamps around. So I rigged an LED to an ESP8266 SOC and programmed it with delays to output a 60hz square wave to the LED. The scope confirms 60Hz +/- 0.2. Unfortunately, it doesn't work as I can't get a reading on the stroboscope disc.
I know I am missing something .. and it might have something to do with a DC square wave vs. an AC sine wave. Can you show me the direction?