I probably won't do this mod yet but since I'm an electronics newbie I thought I'd find out what the circuit would look like. The first problem I can see is that if the subwoofer is turned up too loud, the voltage provided to the speaker would be too high and might burn out the LEDs. But if the speaker is turned down you may not see the LEDs at all. Is there someway to create a voltage limiter which say after a certain volume will keep the LEDs at their maximum brighness? I also had the idea of making the LEDs fade after each beat. IE they'd go from off to on very quickly when there was a drum beat, but then fade slowly from on to off until the next beat would suddenly turn them to full brightness. I hope all that makes sense. Since we've just been doing capacitors at school I imagine this is the way to do it. When there is no power from the speaker, the capacitor kicks in a provides a fading voltage. I guess if I look in my text books I could find out the right capcitance needed to provide a fade which isn't too quick nor too slow. But first I probably need to solve the above problem. What do you guys suggest?
An old Maplin circuit, they may still do a "Watt Watcher" kit. Batteries not needed, it runs off the speaker leads. The unknown resistors R9 & R13 depend on the maximum wattage you want to use. The zener diodes stop the leds burning out. C2 provides a slight fade, increase for longer. Here's my single-led version:
Hmm that's a bit more complicated than what I had expected. I don't even know what a zener diode is or how transistors like that work... . Did you say Maplin used to sell that thing as a kit? Was it just called a watt-watcher. What was it actually used for? And also does the circuit include the fading thing? EDIT: And how does it prevent the LEDs from being overloaded when there's too much voltage..? And also on the circuit diagram, do the values of C1 and C2 mean 47 micro fahrads and 2.2 micro fahrads?
