Hi Everybody!
Been away for a few days, so just catching up on this thread. Thanks for all the replies!
@kevbo - I think I'm going to accept the loss on Darligintons. Less parts, layout not so critical, cheap and easy to get, wide range of substitutes that will work. Slow should be ok, I can use a fairly low frequency, no? It's not meant to be an "end all be all" but cheap and easy to DIY while working fairly well. Got the fast freewheel diodes. I'll look into the parallel cap for faster switching. Assuming a base resistor of 1.8k on a 1000 HFE darlignton, being driven with 5V from a uC pin, do you have a reccomended cap value? As to layout, when I get it down in Eagle I'll post it, and if you have the time, perhaps you could look at it.
@ David HK and dinges - I did build that circuit and wasn't happy either. Besides, with the uC it is easy to add temp. compensation, voltage drop, current read out etc. As well as the auto-shutdown, a feature I LOVE with my present controller.
@treehouse - Yeah, there are some commercial products out there. But I want a simple, cheap, effective DIY alternative that I can make a few of. I like the one I use now, but it is built into my general power controller (that does my solar, windmill, monitors water and power usage etc) so I am building a stand alone version.
@richard - The controller will be used with motors from 5 to 10 HP.
Thanks!
Jonathan