small microphone amp

[laki101]

I need a small, light ,cheap, battery powered microphone (computer like) amp

i need it for my rowing boat so that the rudder man can give orders without shouting as loud as he can

so it would be a computer mic or similar that goes into the amp circuit and than it goes into 2 or 3 (we will see depending on how good everyone can hear ) and it needs two be powered of a 9v battery or a 6v/12v small 2/3 Ah battery

any schematic or idea how to modify one would be great

[gszekeres1]

Goes into what? Horn speakers ? Headphones ?
How long does it have to last ?
Switching amp is most efficient.

[tangmonster]

randomly googled:

this one looks really simple:

Simple Microphone Preamplifier

try it.

you will need to amplify it afterwards using an amplifier.

If you want to go simple , i would look for a cheap car amplifier. and run both circuits of 12V.

Regards

[gszekeres1]

That looks very simple. I would suggest some form of clipping, to keep volume constant,
and help prevent feedback. Some diodes on the output would work.
Love those hand drawn diags...
http://zekfrivolous.com/sub/mikeamp.gif

[laki101]

Originally Posted by gszekeres1

Goes into what? Horn speakers ? Headphones ?
How long does it have to last ?
Switching amp is most efficient.

goes into 6 ohm (3x4 ohm 2 in line and one parallel which gives me the 6 ohms)

and it has to last on a 2,4 Ah 12v battery about 5 hours minimum and more would be great

i was thinking of making the preamp that tangmonster gave and than conecting it to some tda chip
would that work?

[gszekeres1]

Should work. Probably some chip will do all. Remember, horn speakers require
less than 1/10 th the power for the same volume.

[Ron E]

Originally Posted by laki101

and it has to last on a 2,4 Ah 12v battery about 5 hours minimum and more would be great

i was thinking of making the preamp that tangmonster gave and than conecting it to some tda chip
would that work?

Do a search for diy megaphone or bullhorn, as that is what you are really after - you might get some more (if not necessarily better) ideas. I think you can get battery powered megaphones/bullhorns pretty cheap, perhaps cheaper than building one.

http://www.amazon.com/Pyle-Pro-PMP30.../ref=pd_cp_e_2
definitely cheaper than building one.