12v speed control

philipad23

Hi

I have an RC car which works with 12V motor and it does not have speed control. I want to modify it to have speed control. Is there any way to control the 12V voltage with PWM. Or any other way for speed control with BS2?

thanks

Martin Hebel

Essentially you simply need to use the Propeller/BS2 output to drive a transistor which controls power to the motor. Depending on current draw, a 2N3905 may be sufficient, though a 2N2222 would be better. The Industrial control text from Parallax provides some guidance on performing high current drive using PWM.

http://www.parallax.com/detail.asp?product_id=28156

note: It is recommended to put a diode reverse-biased across the motor to provide a current path when the high-inductance load is de-energized which we don't stress strong enough in the text.

-Martin

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Martin Hebel
Southern Illinois University Carbondale - Electronic Systems Technologies

Personal Links with plenty of BASIC Stamp info
StampPlot - Graphical Data Acquisition and Control

Post Edited (Martin Hebel) : 6/4/2006 9:28:04 PM GMT

Martin Hebel

Just noted this is in the Propeller forum, but you ask about the BS2. If it is intended as a BS2 question, please post in the appropriate forum.
-MH