Electronics advice needed for a musical instrument
 

Hello everyone!

I dabbled in RC cars a couple decades ago. Now I dabble in making bizzare musical instruments. The instrument I am working on now will require a Brushless DC motor just like an RC car. What I need it to do is actually pretty simple so it should be possible to do it with already well-engineered RC car parts. Its not radio controlled or battery powered. The BDCM speed is simply controlled by a single 0-5V continuous control pedal.

Here's what I need to know:

1. Do ESCs require battery control or is it possible to power them with an AC-DC transformer? Is there anything I should watch out for?

2. What is the best way to control a BDCM with a 0-5V controller pedal? What control signal does an ESC expect?

3. The motor needs to have pretty high torque at low speed. Any suggestions for a motor? I dont want to use a stepper.

Thanks,
Clark

RC vehicles do not use brushless DC motors. Those are usually used in PC fans and other industrial applications. For an r/c motor, you'd be looking at either a 3-phase brushless or a brushed DC motor.

1. You can run an ESC with a transformer so long as the voltage coming out is clean enough. A large capacitor should help assure this.
2. For an electronic speed control, you can't exactly vary the input voltage. They actually look for a pulse wave coming from the ESC. Not a varying voltage.
3. Since you need brushless DC, r/c is not going to work. Maybe a PC fan? Or you could use a Brushed DC motor...

I would suggest simply using a variable resistor (potentiometer) that will handle the current that your motor will end up drawing to vary the voltage. This will end up being your speed control, even though it won't be an electronic unit (pulse signals to the motor), it'll be a mechanical type (variable resistor).
-Eric

WHAT!! Isn't this a RC website? :blush:

Thanks!
 

Thanks for the advice rccardude04! I suppose that i could simplify things and use a brushed DC motor as long as it is quiet. I always have to go and do things the hard way. :weird:

You can still run an R/C brushless motor and ESC from a DC source. A large capacitor will likely be needed at the ESC power input if using a suitable A/C to D/C power supply.

Do a google search for "servo tester". You will find many circuits that have a potentiometer input, and they then output the proper signal to operate a servo, which is the same signals used to control the ESC.

Good luck,
Craig