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How do I create a speaker that gets louder the faster someone pedals on an electric bike? Answered

For a school project I am building an electric bike and thought it would be fun and an attention grabber if when people were on the stationary electric bike the faster they pedaled the louder a speaker would get. Is that even a possibility? The motor is an 1000 Watt motor on the rear wheel. I think that the higher the voltage or current, the louder a small speaker would get. 


Stick a playing card into the spokes.


6 months ago

You do not need a motor but a generator which usually increases voltage with increasing RPM is what you want..

You want a voltage controlled oscillator feeding that speaker.

Not knowing your skill set.. You understand the tone frequency will increase as the pedal RPM goes up..

A 555 IC can be wired as a voltage controlled oscillator with pin 3 driving that small speaker and because it is a digital output it will have a nice organ tone...

Of course you need to measure the maximum output voltage of that generator you call a motor !? before any values and power supply can be selected...

This motor can be used as either a motor or generator and has a max output voltage of 48 volts.

48 volt 1000 watt sounds like a motor nameplate and means 20.8 amperes of current to provide that power.. Power watts = Volts x Amperes..

1000 watts is 1.34 horsepower which is way beyond the 0.35 HP most recreational cyclists can produce.. HP = Watts / 746

Build your bike and measure the real voltage that you can produce, not the machine nameplate please..

With the bike just being hand cranked not up on a stand, I produced 31 volts. I’d expect more if someone is sitting on it and pedaling.