Need advice/help form any of you electronics guys.

[gregs78cam]

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?

[405cubes]

Is the power supply sufficient? The solid state relays and ic's are real efficient and i would assume so, but if i had a dime lol.

You could use a cap for smoothing out power to the motor.
Try a resistor across the variable resistor and see what happens..
the variable resistor used, is it spec'd amply?

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?

[gregs78cam]

Is the power supply sufficient? The solid state relays and ic's are real efficient and i would assume so, but if i had a dime lol.

Yes it is, it can power a 380, 600, and the large PM motor I am trying to use, when wired directly, so if it can handle the inrush current, PWM should be no problem. And the 5V side is rated even higher, 30A.

You could use a cap for smoothing out power to the motor.
Try a resistor across the variable resistor and see what happens..
the variable resistor used, is it spec'd amply?

I tried a cap to smooth the supply output, no dice. The potentiometer is right for the current.

I think it has something to do with the 12V side and the 5V side using a common ground along with the nature of the switching supply. I will try to add a couple of diodes on the ground legs to help isolate them. But that will have to be later, for now I am just going to run the motor directly from the supply, and simply recirculate the excess flow.