To make a long story short, I programmed a ATTiny45 to control a 550 motor(from cordless power tool) with a solid state relay('03 Caravan). My first iteration was below(don't know why pics are so dark). As long as I powered the ATTiny and the SSR with two different power supplies, it worked fine (SSR and Motor on 12V) as long as the 'Tiny was on my 5V UBEC, or mini-USB for the TEENSY2.0.

Pump control drawing1.jpg

So I thought maybe I could get rid of the TIP102, and just have the ATTiny45 pulse the SSR directly, and it does, But only while on 5V and only if they are from separate power sources.

pump control drawing.jpg

I even tried running the 'Tiny on 5V from the UBEC getting power from the PC supply(5V or 12V), and I just get a jittery motor with almost no speed range.

Any ideas?