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Electret Microphone

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jdp12345

New Member
Hi,

This question revolves around creating a simple microphone that I can connect to my digital recorder.

I bought an electret microphone and a 3.5MM mini phono plug.
The max impedance for the Electret is 5uF and Max 10V.
I know the electret has 2 imputs, voltage & ground.

When I connect the electret to the plug, do I need to place the appropriate resistor to stay within the 5uF maximum (2.2Kohm)? Or will it be automatically regulated by the digital recorder?

Also, in many schematic I've seen on the Web, they include a capacitor in the connection of the mic and the audio output. Do I also need to use a capacitor in my connection?

My digital recorder is an Olympus DS-330.
In order to make my external microphone work, do I need these 4 parts?

1) 3.5MM Mini Phono Plub
2) Electret Microphone 300 - 6Khz
3) 2.2Kohm resitor (to meet .5uF at max 10V)
4) Electrolytic?

or do I simply need the 3.5MM mini plug, the electret Mic and the 2.2kohm resistor?


I'll try to get pictures of the 3.5MM mini plub, but for now, these are my questions.


Note: I was under the impression that creating an external microphone was simply connecting the wires together with a resistor(because I'm very new to electronics) and directly to the plug.
 

herbymcduff

New Member
So, are you trying to say that you want to use an external microphone instead of the internal mic on the digital recorder, to record?

And if so, why can't you just bypass the internal mic, and place your mic in its place?

And what do you mean it has an impedence of 5uf, and Max 10? Impedence is AC resistance, and is labeled in ohm's, not microfarads. And is Max 10 a maximum of 10V out. And if it is 10V out, surely the internal mic doesn't produce that much out. Plus the voltage out of a mic varies, do to voice.

Also a mic doesn't have 2 inputs, it has outputs, though you can use the outputs as an input if you choose to use your mic as a speaker.
 

jdp12345

New Member
Yes, I want to use it instead of the internal mic

Yes,

I want to use it instead of the internal microphone.

The information on the Electret is as follow:

.5uF Maximum Current Consumption
10 Maximum Operating Volts

JP
 

jdp12345

New Member
You're right Kinjal

Your right Kinjal.

It is 0.5uA. I apologize how this information threw averyone off track.
After getting most of the basic information right, with all your help,
I don't think anyone has done this kind of wiring before.

All I have received is correction Email postings and not concrete guidance
for my question. At least, you all have helped me get the correct words in this posting, which I appreciate.

Thank you to all that responded and to those that didn't.

Sincerely,

JP
 

mechie

New Member
Surely the answer you requested is in Pilot's posting, the website he suggests has a diagram headed "Common or Garden Variety".

This is a simple circuit to feed the electret's internal pre-amplifier (usually a single FET) with power via the resistor and seperate off the audio via the capacitor - the cap is required to stop the DC power from upsetting your digital recorder's input circuitry.

Your max 10V rating is the most the electret's internal amplifier can stand before it cooks - much less will be fine - try 1.5v or 3v.

Use the components in the diagram (there's no magic here - 2.2k or 3.3k will make little real difference; 0.5uF or 1uF it's all the same !)

Other types of microphone (moving coil for example, or crystal) may require no pre-amplifier - just direct connections to your jack plug.

NOTE - for those who will be checking, the mic's effective impedance will change with component changes but in the practical world, with a blindfold on could you tell one from the other in a typical hobby application !
 

herbymcduff

New Member
mechie's right. I checked out Pilots site, and it has everything you need there.

Also, why don't you measure the output of the internal mic, and try to get your external mic to match it, and just bypass the internal mic.
 

jdp12345

New Member
Thank you Mechie

Thank you for your posting Mechie.
You're right, I did not include the great help from Pilot!!

You reminded me that he posted a great web site for guidance.
Once again, thank you all, especially to Pilot and you (Mechie).

Sincerely,

JP
 
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