Quote:
Originally Posted by jyanof
I do plan to switch out the 555 timer at some point, and I have zero experience with micro-controllers. But, your success so far with the motor controller gives me hope! Were you able to learn just from the application notes? What materials would you recommend to help learn?
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If you go with AVR, there's
AVR Freaks
They are very helpful. I always had an answer to any question I had before the end of the day. I learned mostly how to do stuff from the data sheet. It was one horrible week.
Quote:
Originally Posted by jyanof
I'll have to try the small caps on the driver input - you're referring to the signal input, right?
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Ya. In addition to the small capacitors, I also use two 4.7uF tantalum capacitors in parallel (which I guess are still small haha) connected from the signal input to the gate driver to ground. If you use electrolytic capacitors, they will get really really hot, in fact, any capacitor with too large of ESR, it will burn up (at least it did in my case).
Quote:
Originally Posted by jyanof
As for the diode, it appears that the spike takes about 100 ns to build, but I couldn't find the forward-recovery time (is that right?) in the data sheet and I have no idea whether a typical diode can handle that. I haven't tried removing one of the two inductors, but that could at least verify the source of the spike.
Lotsa stuff to try! Will have to save it for another day...
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The diodes I'm using have a reverse recovery time of 22ns and forward recovery time of 220ns. It's sort of weird. 220 ns seems like a long time, but I didn't have any problems with spikes. I'm switching at 16 khz.
What switching frequency are you using with the 555 timer? Higher switching frequency can prevent the capacitors from draining completely, and might allow you to use a smaller inductor for smooth current, but I think you can overcome the voltage spike with the right diode. It must be possible, dang it! haha!