Simple control of KBIC type DC motor controllers?
I understand that the POT leads on the ubiquitous KBIC and similar 90v dc motor controllers are "hot" and you can't just control them directly with a digital signal. (Otherwise you let out the magic smoke.) You need some kind of isolation between the digital circuit and the "hot" mains level voltage pins the POT hooks to.
I was looking around and came across an "idea just so crazy it might just work", LOL.
In concept.... wire a LED to a PWM controlled pin on the parallel port and use appropriate current limiting resistors.
Stuff it in a tube, and on the other end connect a photoresistor and wire it between P2 and P3, and use a ~10k resistor between P1 and P2 to provide a pull to the low side.
As the PWM LED gets brighter, resistance drops and the motor goes faster.
Things that may make it "wonky" are the non-linearity of the photoresistor and the response lag? For $5 or so it may just be worth a shot, LOL.
Is there such a device already packaged in an IC? "Opto-isolators" always seem to be digital or to have a built in transistor that outputs voltage?
Q: How many tools does it take before a simple task becomes a project?
A: Just one. I'm the Tool that turns a simple task in to a project.