UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment


Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Thread Tools
Old 16th Jun 2019, 11:25 am   #101
DonaldStott's Avatar
Join Date: Aug 2015
Location: Glasgow, UK.
Posts: 713
Default Re: Turntable Stroboscope

Originally Posted by GroovyG View Post
Regarding the perceived brightness of the LED, there's a phenomenon whereby a short duration flash is seen as being brighter than one of longer duration, even of the the same actual brightness. It's too long now since I was an optometry student, and I've gone off in altogether another direction since, so the details now elude me, but I'd expect a 208μs flash to be comfortably in the relevant range.
Thanks GroovyG - another optometric phenomenon I've learned about today!

Looking back at my Post #60 above where I did a quick calculation that we want the LED to be on 1/16th of the time which is 3333μs divided by 16 (or multiplied by 0.0625) = 208.3125μs.
BVWS Member
DonaldStott is online now   Reply With Quote
Old 16th Jun 2019, 10:23 pm   #102
Join Date: Nov 2015
Location: Witney, Oxfordshire, UK.
Posts: 97
Default Re: Turntable Stroboscope

Of course, flashes at 300hz are well above the eye's critical fusion frequency - that at which individual flashes cease to be distinguishable - which itself varies according to stimulus brightness and retinal location. (Thus, you'll have noticed that the flickering end
- 50hz at the ends - of an old fluorescent tube is much more apparent in peripheral vision than when looked at directly.)
GroovyG is offline   Reply With Quote

Thread Tools

All times are GMT +1. The time now is 10:50 pm.

All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at
Failure to heed this warning may result in death or serious injury to yourself and/or others.

Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.