By Forrest M Mims
I just found this out!
I have a bunch of LEDs laying around, wont be buying optocoupler any time soon
Has anyone here ever experiment with this?
https://www.jameco.com/Jameco/workshop/diy/two-way-optoisolator-forrest-mims.html

 

Experiment with it. Optocouplers are optimized for speed and coupling and CTR.

Also variation one "coupler" to another, because they are not tested for parameters,
could pose design issues.

This approach clever, but not ideal, so experiment. Will be interesting
to see what speed you can get out of it.

When you experiment might make sense to use white heat shrink to get max
transfer of light between LEDs in the coupler.


Regards, Dana.

 

The idea has been around for a few decades. I think I saw it discussed in a paper from Hewlett-Packard (who made LEDs at the time). Don't know if a practical use ever emerged.

 

Many moons ago I made a digital darkroom timer to control an enlarger.
Optocouplers were not readily available. In its place I used an LED and LDR to activate the TRIAC.

 

Has anyone here ever experiment with this?

Yes. The results were underwhelming due to the miserably low current transfer ratio.

Cute idea but not very practical IMO.

 

I needed a high speed HV switch for as DIY project. So filed off the
top of T03 transistors switch cover, and used a photo flash tube
to turn it on, a ballasted string of them.

Worked pretty good, uS kind of speed as I recall. Switching 500 - 600
Volts if memory serves me. 40 years later I am sure there are better solutions



Regards, Dana.