microphone + headphones + battery power

[truthbetold]

Hey.

Basically I want to have a microphone pick up sound and have it played real time on the headphones. No need for recording or anything like that. My preferences would be for this to be small and battery powered. I can do this I know by just putting a mic on my pc and connecting headphones, but I want this to be more lightweight.

There are expensive battery powered mic preamps out there, I know. I am trying to make, modify, or buy something very simple and cheap; it could perhaps be done with some scrap parts, or maybe there is a small circuit already wired that does it. I don't know.

Any suggestions?

Thanks!

ps If this seems a strange request it is something that is being integrated into an art piece -- I am just getting in to adding sound and electric/digital components to the work.

[lineup]

search www.google.com for:
electret microphone amplifier build
or something like
electret mic preamp diy

for headphone amplifier you can use one op-amp
this is simple and very good solution

see this project, for example
http://www.headwize.com/projects/cmoy2_prj.htm
Uses for example 2x9V battery supply. Which is very good hi-fi option!

At http://headwize.com/projects/index.htm there are more projects.
As well as several in our forum here.

[TheSeekerr]

Electrets give a fairly strong output - a cmoy with a gain of, say, 50, would do the job.

http://tangentsoft.net/audio/cmoy-tutorial/

For the input, you'll need a "battery box" circuit. I've attached a simple one. In the diagram, Rr and Rl are 4.7k ohm metal film resistors, and Cl and Cr are 2.2uF polyester capacitors.

Hopefully, you can see that the amp and battery box can be connected to the same battery.

So, you would have it set up so that:

Electret Capsule > Battery Box (provides bias voltage, then blocks it from entering the amplifier) > 10k ohm volume control potentiometer > cmoy headphone amplifier (configured for high gain because of the lowish output of an electret compared to a typical source) > Headphones.

All clear?

EDIT: Total cost will be dominated by the capacitors and the opamp - you're looking on the order of $50 or so.