well it's definitely not the LED that's doing it, because even if i point it off-axis and cover the LED with cardboard or my finger or whatnot, it still makes the sound...

so you're thinking it's being caused by an inductor, eh? hrm... well it's definitely less fun than an LED. but maybe i can still think of something fun to do with it...

so you're thinking it's being caused by an inductor, eh? hrm... well it's definitely less fun than an LED. but maybe i can still think of something fun to do with it...

my electrical engineering knowledge is next to non-existant. that said, the closer you put the part of the remote containing the batteries to the pick-ups the louder the sound gets. also most remotes make completely different sounds. i've been doing this to make friends shake their heads at my free time for years.

I tried to do this, because I build those "light sensitive" theremins every once in awhile, and I like the way the IR light affects the sound and I wanted to be a fancypants and integrate this into the unit. However, I really have no knowledge of anything, so I ended up blowing up the IR LED. Pretty stupid.

i think i have an idea that might work for a fairly analog way to do it.

it's a simple oscillator using a Schmitt-trigger NOT gate. there's a capacitor and potentiometer in the feedback loop to control the frequency of the oscillator.

the oscillator drives a transitor (level shifter), which drives a power FET. most of the International Rectifier parts should work. and they're available from Digikey. you could use regular power BJT's as well.

there's another potentiometer used for the 'volume' of the noise box. it just changes the current through the inductor coil.

the 'inductor' coil can be as simple as wire wrapped around some small cylindrical iron core. (think about battery/wire/nail trick to make a small electromagnet in science class). i've gotten steel dowels from home depot. the more wraps of wire, the stronger the magnetic field.

i have a schematic, but i'm too dumb to post it. if someone else wants to post it, i'll just mail it over.

some of the values will probably need tweaking, but it should get someone started. i think it's a cool idea, but i'm too lazy to actually build it.

rock on.
-mikeC