Mic input transformer for DIY Project

[tINY]

Is this a Stereo mic input? And, does it somehow supply +5v bias for condenser mics?

As far as getting the transformers, I am told that Edcor is pretty good and inexpensive. For small quantities (like 2) you may just get Jensen and be done with it....



-tINY

[Martin Kantola]

Fouko,

you don't need a transformer, it will not help the sound in any way! Operate your microphone on an internal battery and connect pin 3 of the microphone to ground (pin 1) with a 10uF capacitor. Your output signal is on pin 2 of course, feed this to both tip and ring of the miniplug if you want the same signal on both recorded channels.

Martin

[Fouko]

Thanks a lot for your help.

Martin Kantola, is it possible to add on your diagram 2 potentiometer to plug 2 mics on the same miniplug ?

Is the the diagram will be like this ?



Thanks

[Martin Kantola]

Fouko,

very neat drawing! You should reverse the polarity of the capacitors so that minus goes to ground. It might also work without them, depending on the microphone.

Your idea of a potentiometer can be problematic with regards to noise, and also because there probably is a DC voltage (plug-in power) on the camera input.

But it's a simple circuit, why not build it and find out what works?

Martin

[Fouko]

I have test the DC voltage on the miniplug, correct there is about 3v on it

how I need to modifie the diagram with this 3v from the miniplug.

Also, are there some characteristics to choice the potentiometer ?

thanks,
Excuse my frensh / english

[Martin Kantola]

Fouko-san,

the potentiometer should not be too high a resistance, and you might need to use a DC-blocking capacitor on the output to prevent a scratching noise when you turn it. Good luck, please report your findings!

Martin

[Fouko]

Because I have done some change I copie my last message.

How can I find the value I need for the :
- DC-blocking capacitor
- potentiometer

Because I have done some change I copie my last message.

I have test the DC voltage on the miniplug, correct there is about 3v on it

how I need to modifie the diagram with this 3v from the miniplug.

Also, are there some characteristics to choice the potentiometer ?

thanks,
Excuse my frensh / english