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I am putting together a kit that has chipcoder for an audio prop.
the kit has an electret mic for input, but I want a line in so i can
just plug my computer into it for input.
I read somewhere that you don't want to just put a miniplug jack in place of an electret mic because there is too mugh voltace across them.
the article i saw that in had a diagram that you can easily build to bypass this problem.

Does anyone know how to do this or remember seein such an article?
 

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Discussion Starter #2
Ok, i found the article that mentioned the modification. It is here:
http://pages.prodigy.net/bq549/projects/boris.htm

Does this seem like it would work the same for my kit voice recorder to replace the electret mic with a miniplug line in and a 100mfd cap?
Is this a bad idea?
Any other ideas or thoughts?

[Here is the text from the article]
Microphone to Line in
Step 1
This modification is rather simple. (inset above) Open up Boris's head, carefully remove the black plate, via the 4 screws, trace the microphone wires to the board.Unsolder the (white lead, old Boris, 1999) (red lead, new Boris, 2000) Place a 100 mfd electrolytic capacitor inline, solder the (+) lead to the board, where the mic wire had just been removed, and the (-) lead to the mic wire. Be sure your solder job, or the bare leads of the cap do not come in contact with any other part of the circuitry. Reassemble Boris.
The importance of the capacitor
Boris uses an electret microphone which means there's DC voltage present across the mic.
The purpose of the capacitor is to block the DC from going into your audio equipment.
Step 2
Cut the wire towards the mic end, leaving several inches, in case you ever want to re-attach it. Strip
the wires about 1/2 inch or so, solder them to an 1/8 inch phone plug. Connect the line side (the insulated wire) to the inner
lug. Connect the shield, (bare wire) to the outer lug. Now just plug Boris into any headphone jack, your portable tape
player, Boom box, or the line out of your computer's sound card.
 

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That looks like it will work for the kit you have. I've got one of those as well, but I don't use it for that very reason - I can't use a Line In signal. Let us know how this works out.
 

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Discussion Starter #4
Here is my report:

I hooked it up last night with a 100 mfd cap and a line in from my computer and other audio sources such as a minidisk player, and it appears to work great. It is pretty sensitive about input volume though. But once you get a good input setting you are good to go.
 

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Sounds good! Could you post a pic showing the connection points on the 100uF cap? Thanks!
 

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Discussion Starter #7
What I did is cut a slit into the card itself ans epoxy a 2 lead header into the slit. then I used two short jumpers to jump from the original mic location to the header. I covered the jumpers and solder connection with epoxy also so they wouldnt snag and come apart.
This way it would be easier to test out the plan and I can hook whatever I want to the input and not be tied to the cap if i didn't want it.

So then I modified a cable that already had a miniplug connector on one end and soldered the cap to the wire itself and taped it all up so that one wire of the miniplug is sticking out and the other wire is the lead of the cap itself.
If you look closley in the picture you can see the end of the cap.

Obviously once the chip is loaded with the audio i would take the input wires off and put the card into whatever prop it is going in.

In this case it will go into this head for a while.

Here are pics.
http://good-times.webshots.com/photo/2698960540100824721ppnZoV

http://good-times.webshots.com/photo/2196020540100824721pAdNQb?vhost=good-times

http://good-times.webshots.com/photo/2510348340100824721bUkHbB?vhost=good-times
 
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