DC motor speed control

** Give this man a prize for his honesty.

In the words of America's most famous living philosopher:

" A man's gotta know his limitations ... "

.... Phil

Google for "pulse width modulation" (PWM). The idea is that the DC from the battery is sent to the motor in pulses, but at a very high rate so the motion seems smooth. You control the speed by controlling the "duty cycle", which is the percent of time the pulse is actually on.

Since you are new to this, I strongly suggest you invest in a prototype board that allows you to plug in components and test your circuit before you actually hard-wire it. Start by getting the PWM circuit to work, maybe watching the waveform on a scope. Then use it to control something like the brightness of a small light bulb or LED, then try a small motor, before you finally get up to the actual bike motor. Each stage of this process requires bigger current-handling ability... bigger output devices, bigger heat sinks, bigger $$$, and more smoke if/when you screw up. Go slow!

Best regards,

Bob Masta DAQARTA v4.00 Data AcQuisition And Real-Time Analysis

Scope, Spectrum, Spectrogram, Sound Level Meter FREE Signal Generator Science with your sound card!

What Phil is saying to you is that this is not a beginner project. You will be controlling some heavy current and the cost will not be cheap. One suggestion would be to bank your batteries and tap different voltages. You will lose torque at reduced voltage but it can work. May I suggest a different approach? Get a geared motor and turn your pedal sprocket at your normal pedal pace and use the bikes gears. Good Luck, Tom

Please do tell me - who is America's most famous living philosopher who can be credited with saying that first? Tim Allen?

Please do tell me - who is America's most famous living philosopher who can be credited with saying that first? Tim Allen?

** Hardly.

The comment is from a famous movie released in 1973.

Allen was still in school or jail back then.

..... Phil

One of my favorites Phil. The cable company is running his movies all this week. G,B& U yesterday, Fistfull of Dollars today.

Tom

G, B and U is one of the all-time greats. Simple story, nice cinematography, nice sound, good characters and Eli Wallach. Very few flaws, such as the commander of the union force in the battle scene. I've seen it countless times and it's always a fun time.