Mar 212012
 

I should be working on the Sparkfun AVC, but this is fun.

I scaled up the LED driver so that it runs a Luxeon Rebel at 400 mA! I don’t even have to point the Rx at the LED any more: I can pick up a signal from the scatter. I’ll definitely have to try this system over a long range.

I modified the circuit to run at 12V, 400 mA with a TIP31. That power resistor is overkill, but it’s what was in the junk box.

Too bright to look at!
 Posted by at 11:29 PM
Mar 202012
 

As promised, here are the schematics for the simple LED voice transmitter.

Simple two-transistor circuit fun

And here is a short video going through the design of the electret mic amplifier.
 Posted by at 6:59 PM
Mar 202012
 

Heres a photo of the Tx and Rx system. The Tx is on the left and runs off of a 9V battery. The Rx on the right runs on 3AA cells. The 9V power worked great for about two weeks until the photodiode decided to give off a big puff a magic smoke.

Schematics coming soon!

Here’s a Tx and Rx pair. The first prototype of the voice modulator is installed on the Tx.
Here’s the burned up amplified receiver. I ran it off of 9V for weeks before it decided to give up. It gave off a strange death squeal that I heard in the speaker before it went dead. 
It’s not supposed to be black inside. Very stinky when they go boom.
 Posted by at 1:03 PM