# What's the difference between 33 1/3 60 vs 50 Hz?

This question comes from a previous post concerning a free strobe disk. At the site there is a 60 hz and a 50 hz version. I thought the hz is the # of AC cycle or at least is a measurement used for electrical purposes. The 33 1/3 is RPM's. Why are these measurements of 2 different entities used to make 2 different strobes. I understand why you need a different one for 45 or 33 but don't understand the difference that hz makes. Can someone explain this simply?
artemus_5
5 responses
 04-15-2002 6:16pmStrobe discs are typically used with some kind of an electric light powered by AC current. Flashlights won't work, and most users do not pay up for a calibrated strobe flasher. The AC-powered electric light will flutter or blink at twice the AC frequency. The 60 Hz driven light will flutter faster than the 50 Hz driven light, and so the dot spacings on the strobe disc need to be spaced closer together for 60 Hz. 04-15-2002 6:50pmIf you do not own a KAB strobe, you may substitute a neon test lamp used to check for hot electrical circuits. These look almost like a flat plastic ball point pen, but have two electrical leads. Connect the leads permanently to an electrical cord, get the room dark and hold the test lamp next to the strobe disk. Electrical test lamps sold in the USA are all 60 HZ and very inexpensive. Possibly even available from Radio Shack. 04-15-2002 7:09pmThanks guys. Now it makes sense 04-16-2002 6:12amActually, any florescent tube light will work. I believe the watt saver lights (the ones that give off 60 watts, but only use 11 watts) are condensed versions of florescent lights. The trick is to get the intensity low enough so that you can actually see stationary marks on the disk. I remember playing games with a binder to limit the amount of direct light on the calibration disk. 04-16-2002 6:13amActually, any florescent tube light will work. I believe the watt saver lights (the ones that give off 60 watts, but only use 11 watts) are condensed versions of florescent lights. The trick is to get the intensity low enough so that you can actually see stationary marks on the disk. I remember playing games with a binder to limit the amount of direct light on the calibration disk.