/diy/ - Do It Yourself

Do you remember a guy askinga bout optocoupler speed and load resistor that was too dumb to read the datasheet? Well that was me.

Anyways, even with proper load the pc87 rise/fall time can't go lower than a couple microseconds. BUT
I've built and tested this circuit, and managed to get it down to 100ns (in a breadboard, so when soldered it'll be less). What it does is diminish the changes in the coupler Vce and that helps with the miller capacitance. I'm posting this because 4 pin optocouplers are quite cheap and some of you might be put off by how slow they might be.