Tape Op Mic - Talk Back mic?

[T-rex]

So I built a Tape op omni the other day and it's great. I ordered some parts to build another couple and got the idea that it would make a great talk back mic; omni, clean, good pick up etc.

So I did a quick prototype last night but the output was way low. This time I used a 9 volt power adapter so I could us a wall wart as oppsed to a 9 volt.

Being very new to the electronics thing I have a few questions:

1. Is there any problem using the wall wart directly in place of the 9 volt battery? A little added noise isn't going to break me since this is talkback.

2. Where is the best place to put the momentary on switch, directly after the mic or at the end of the chain right before the 1/4 inch out to the mixer.

3. Should I break the positive or negative or does it matter?

4. what would be the best way to stop pops from pushing the switch down? Resistor before or after the switch etc.

Any help greatly appreciated!

[jajjguy]

jeesh, maybe that's just too techie for this board... but i thought it could use a bump.

[T-rex]

Thanks man! I figured with the Mic Fun For All thread that someone may have some answers. When I get some time to really sit down with the circuit I am sure I can get it working well and if so I will report back.

[Scodiddly]

A wall wart should be fine... might want to add a nice big filter cap to the power supply to smooth it out a bit more.

The output level is what it is... a higher power supply voltage will just get you more headroom, not more gain. But if you were willing to look around for a basic circuit you could goose the output up quite a bit with a single transistor and a few other bits.

Breaking the signal lines tends to generate a lot of noise - DC builds up in the circuit when disconnected. Try shorting between + and - at the talkback mic input instead. Have a "bleeder" resistor between + and - at the same point, maybe 10k-100k, to bleed off any DC when the switch is open.

[federal donut]

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[T-rex]

Thanks Scodiddly! That exactly the info I am looking for, you rule.

I found the output problem by a slight deviation from the original circuit so that is better now.

I will keep you guys posted when I get it in good working order. It will be a lifesaver to have a decent talkback system without having to spend a lot of cash.