Quote:
Originally Posted by jyanof
It's been implemented in the form of overspeed protection. It doesn't calculate a specific RPM, but calculates a number; if that number is above the threshold you provide, power to the motor is cut.
The calculation could probably be modified to produce an actual rpm value or a proportional PWM signal. It will be very inaccurate at low speeds and will also vary in accuracy at different output currents. For example, I noticed that the overspeed would trip at lower RPM if the motor was lightly loaded. The difference was small though, maybe 400 RPM between an unloaded motor and a highly loaded motor.
Also, no calculations are performed when you're coasting (since motor voltage is zero) so the tach would also go to zero. Might be a little weird to get used to...
Lastly, this calculation only works with series wound motors, hence the modifications required for Jack and his compound motor (i think it's a compound, anyway).
If you try it though, let us know how it works! I've had a dead tach for 2 years now...
btw, you can feed a traditional tach with the signal produced by a couple of magnets on the motor tailshaft (or shaft adapter, i guess) and a home made sensor of a couple hundred turns of fine magnet wire around a screw. Put the screw/magnet wire close to where the magnets pass and they will produce a voltage as they pass by. Use a 12v zener to clamp the output to 12V and feed it to your tach signal input. That's the jist of it, let me know if you want more details...
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I had another thought while at work today, what about hijacking the rev counter for use as am ammeter? Instead of reading 0-7500 1/min, maybe set the scale to 0-750A. I suspect the hardware off the MCU wouldn't be to tough; maybe an isolated op amp to boost the pulse signal to something the rev counter will be able to read.
Quote:
Originally Posted by jackbauer
The Bauer-con is basically an igbt output stage. Some modifications to the control board will help such as using a dc dc with a 15v output and the little two resistor and ultra fast diode circuit posted way back to help with the turn off.
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OK Jack. Do you have any pictures of your system? I'm curious about how you arranged your capacitor bank. After I read the rest of the ReVolt sub-Forum, I'm going to watch all of your YouTube videos.