Finally got around to editing video of my experiments in improving response times of slow low-cost #optocoupler #optoisolator ICs such as the #PC817

https://youtu.be/s1l86nTIWEE
The improved speed was sufficient to pass #MIDI data (31250 bits/s) through it

#cascode #electronics #transistor #amplifier #YouTube

@mike805
I tried the #cascode #amplifier trick with the PC817 #optocoupler. IMSAI Guy only showed how the voltage of the transistor base affects the speed of the falling edge. But notice how the rising edge remains largely unaffected.

By comparison, the common mode NPN #transistor amplifier with 150 ohm resistor across base-emitter, yielded noticeably sharper rising/falling edges
#electronics #oscilloscope

@mike805
[IMSAI Guy] explains the cascode amplifier trick
https://youtu.be/APUhm2tsCiE

See Figure 13 High bandwidth optocoupler configuration
https://www.onsemi.com/pub/Collateral/AND8273-D.PDF

I might need to try that for comparison

#cascode #amplifier #optocoupler #electronics

Testing the switching characteristics of cheapo PC817 optocouplers from Ebay.
555 timer astable is generating a 37kHz square wave test input.
Rise/fall time is way out of spec for use in #MIDI. But the recommended component, 6N138, is much more expensive.

Instead have the #optocoupler drive the base of an NPN #transistor and by adding appropriate resistors, I get much improved switching speeds. Is this good enough for a MIDI input circuit? #electronics #oscilloscope #breadboard

How Home Made Robot Arms Used To Be Made https://hackaday.com/2023/02/14/how-home-made-robot-arms-used-to-be-made/ #parallelport #RobotsHacks #optocoupler #robotarm

How Home Made Robot Arms Used To Be Made - With laser cutters and 3D printers in our arsenal as well as the global toy shop o... - https://hackaday.com/2023/02/14/how-home-made-robot-arms-used-to-be-made/ #parallelport #robotshacks #optocoupler #robotarm