Im not dead, im assembling it and testing it with the ocilloscope, to make eveything alot easier and cheaper, ill just use the power source as a 5V which any home charger can handle.
Hey everyone, I took a different approach to the cassette tape speed and I found an alternative motor for driving cassette tape. I did simulations to play the cassette tape and the rpm varies between 20-50 rpm. The motor is small which is good becauseit keeps the small form factor.
Ok i'm just ordering parts for measuring RPM from EMF. Based off the overall project I think only an arduino pro mini or teensy might be used. Thats good because the cost to build this thing will dramatically decrease.
@Morning.Star Microchip TC652 uses FanSense(tm) to sense commutation of a DC brushless fan. They basically AC couple the current signal from a sensing resistor.
The speed is (was) normally stabilized without a tachometer, except in high class tape decks. Often analog motor control chips were used which evaluate back EMF of the motor and/or implement some kind of "negative resistance" to compensate for the rotor resistance. Without this resistance the moor speed would be perfectly proportional to the applied voltage, independent of mechanical load.
Sometimes such a control circuit was included into the motor casing.
Another possibility would be a brushless motor, where you get inherently a frequency proportional to it's speed. This can also done sensorless by evaluating back EMF of the winding which is not driven at the moment.
Except my motor has a commutator. I was thinking of sampling the feed and counting the EMF spikes for metrics as a free replacement for encoder wheels etc, but I'd never heard of it being done. Damn, but at least I know it works. :-)
Interesting concept,
Quick question, how are you going to keep wow and flutter in check with only one spindle.