PWM Speaker Project Page 1

this is a 10uf 25V capacitor that I soldered in series in the + input wire inside of speaker box.Most circuits used to drive loudspeakers produce an audio (AC) signal which is combined with a constant DC signal. The DC will make a large current flow through the speaker due to its low resistance, possibly damaging both the speaker and the driving circuit. To prevent this happening a large value electrolytic capacitor is connected in series with the speaker, this blocks DC but passes audio (AC) signals.

Drilled thru the speaker housing and mounted this pot inline between the capacitor and the speaker. Also mounted a small slide ON / OFF switch in the - speaker wire. Its to turn off the speaker after making adjustments to your PWM, frequency generator.................update Chemlec informed me:...A 50K Pot is WAY TOO LARGE.

A 500 Ohm or a 1K Pot would be MUCH BETTER.

And you need to wire it so that One outer terminal of the pot, Goes to the Minus input as well as connected to the Speaker Minus.

The Other Outer Terminal of the pot goes to the Input Capacitor.

And the Center Terminal of the pot Goes to the Speaker Positive.

This will give you TOTAL Control over the Volume.

Here is the frequency speaker back together. Chemlec advised me to use either a 10uf or a 100uf capacitor to block the DC current, I opted for the 10uf. The unit seems to work very well. ........Notice this is not a PWM just a tool to use while adjusting one.

This is a shot of the quick connects on the back of the speaker housing. You must watch your polarity when wiring up this speaker to listen to your cells frequency. Chemlec also warned me that using to large of a capacitor would cancel out the PWM's pulses. Be creative, You only need turn it on while makin adjustments. Ideally, wire speaker across cell.