I’ve been working on this project since I woke up this morning… about 1.5 hours ago. But I now have it successfully working with a piezo speaker as a microphone. I had to run the speaker output through an op-amp in order to get it working, but it does work. The only problem I’m having with it is that it only picks up noise that is RIGHT next to it. It’s probably just the crappy speaker, but I might be able to help it out by bumping up th amplification again. Also, I am using a quad op-amp because it’s all that I had laying around. I’m only using one of the op-amps on the IC so I’ll have to go pick up something smaller. I DO want to wear this eventually so size is key.
Here are some of the helpful references I have used so far:
Datasheet for the LM386N quad op-amp I’m using.
Instructable someone created about how to build a VU meter.
4/11/08 – 5:51 PM
I have completed the vu meter tie circuit – or so I believe anyway. After purchasing two new microphones from RadioShack for this project, it turns out that one I had lying around here isn’t broken as I had originally thought. In fact, it works WAY better than the other mics I just bought. This one is much more sensitive to my voice. I think I finally have the correct resistor ratios for the amplifier circuit as well. It’s all coming along quite nicely. I will try to post up some pictures and get schematics drawn up later, but for now I’m off to Target to hopefully purchase some stamps. Does Target even sell stamps?