Instructables

Audio Flame Feedback

This instructable shows you how to build a light controlled sound generator. Here i've built an unstable feedback sculpture with the sound generator and a candle. The speaker makes the candle flicker and the light from the candle modulates the signal headed for the speaker. Air turbulence makes the relation between the speaker and the candle unsteady, so it bounces between different semi-stable modes.

The circuit to create and amplify the sound isn't trivial, but it's made of simple building blocks. I'll show you how to build a light sensor with a CdS photoresistor, a simple op-amp preamp, an oscillator with the classic LM555, and a 5 watt power amplifier with the LM1875.

You can do it if you follow the instructions, I'll try to explain the details.


 
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Step 1: Stuff You Need

I used a bunch of stuff to make this project. I prefer to get stuff from Jameco and Radio Shack because they're super convenient and I do everything at the last minute. You can get everything from Digikey also, or whatever your favorite electronics supplier is, none of the parts are exotic.

You'll need:

A speaker.
A candle and candleholder.

Wire - I like to have around two 3-packs of wire from radio shack, one solid core and one stranded. I prefer 22 gauge.

Perfboard - I like the board number 276-150 from radio shack, it's cheap and useful.

Power supply - I designed this with the Mean Well 24V 1A wall wart from Jameco. You'll need one of the corresponding jacks also if you don't want to solder the supply directly to the board.

Electronics components - You can get all these from Jameco.
Resistors:
2.2 x1
1k x1
5.6k x2
10k x4
22k x3
33k x1
100k x1
200k x1
1M Audio Taper Potentiometer
Photoresistor (I used Jameco #CDS003-7001)

Capacitors:
0.1uF x3
1uF x3
10uF x5
100uF x3
2200uF x1

Semiconductors:
MC1458 x1 (Any general-purpose dual op-amp is fine, these are cheap)
LM555 x1
LM7805 x1
LM1875 x1 (plus heatsink)
1N4733 x1 (Any 5V Zener diode is fine)
8-pin DIP sockets x2 (DIPs are hard to remove if you blow them up accidentally, best to socket them just in case. The LM7805 and LM1875 are in TO-220s, easier to pull out of your board if necessary..)


Tools:
Soldering Iron & solder
Pliers, wire strippers, diagonal cutters
I have a similar speaker i want to run just the magnet for a few days straight as a chladni plate, do you think this amp/preamp circuit would hold up with a cooling fan?
Taneth1113 years ago
Would it be possible to get a clearer version of this? I can't seem to find the MC1458...
dandroid (author)  Taneth1113 years ago
I think it's pretty clear if you click through to the full resolution version, even if the picture on this page is a little tough to read. Anyway,the MC1458 is a dual op-amp, one is in the bias section and one in the preamp section.
crjeea3 years ago
As with many of my ideas...
now you have had the brilliant concept idea... now to think of a use for it (:
take care
good luck to you (: and happy hacking (:
8bit3 years ago
very very good idea.
bluedragon4 years ago
dude that is sweet
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