Damage possible from powered mic in socket for un-powered mic? [OT]

I have a portable flash-memory recorder which has a mic input.
The input socket has "Plug-In-Power" this provides power to run a
suitably-designed unpowered electret mic which is plugged into the socket.
If I use one of the older-style electret mics which contains a battery for its own power then would that severely overload the input electronics of the flash recorder?
If so then could such an arrangement actually cause damage to those electronic components?
Alex
[ Basic tech info for Plug-In-Power = www.telinga.com/pipwp.htm ]
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Alex wrote:

I'm presuming we're talking about a jack plug & socket here? Mono or stereo? The jack plug has a tip and rings for the audio and DC power? Maybe insertion of an unsuitable plug eg the one on your battery powered mic might short the DC? Anything in the instructions/user notes/online manual about that?
I wouldn't think that the signal level itself would cause damage. I have used an 1980s Tandy stereo mike (with an new AA cell in the barrel) with a PC sound card and I had to crank the input gain right up compared with the cheapo (unpowered) mike in my webcam, not that that proves anything much
Maybe a Google is order for a more specialised forum?
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snipped-for-privacy@gmail.com wrote:
I looked belatedly at your link. I don't think you'll be damaging anything.
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Try it with no battery installed. There is usually just an FET and pull up resistor in it. Removing the battery should leave just the FET and you'd have the pull up resistor/voltage source inside the flash recorder - the way standard un powered electrets work.
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Doubtful - the output of the OP's powered mic appears to be capacitor coupled, so there's no DC path to supply the FET.
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wrote:

Well, cap coupled wouldn't work. I'd try it, nothing to lose, and wouldn't you feel stupid if you didn't try that first?
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default wrote:

No, since I don't expect it to work like that when its designed properly. Also, you are applying a reverse voltage to the coupling capacitor if you try this.
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wrote in message

Since you mention that, if the cap is a tantalum even a small reverse voltage can cause S/C failure - so it could work after all!!
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wrote in message

That is why a non-polar tantalum is used in this application.
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wrote in message

Didn't know such things exist! - got a pdf?
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wrote in message

GOOGLE is your Friend for Internet look-ups !
Non polar tantalum capacitor - US Patent 5777840 http://www.patentstorm.us/patents/5777840-description.html
Data sheets http://www.digchip.com/datasheets/parts/st/parts_st41.php
Vishay http://www.datasheetcatalog.com/datasheets_pdf/T/C/TC.shtml
Kemet FAQ http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/0CBE2E5238A759A385256A8700515CCD?OpenDocument&source=find~~Capacitor+Selection
You can read it straight from Bob Heil (and yes he installs and sells these with this products) A non-polar electrolytic, if available, could also be used.
IF you use other microphone elements (copper wound, magnetic bobbin, dynamic) -- on a "phantom powered" device --- then the DC power must be de-coupled. You use a capacitor to block this DC power. A 1 mFd. non-polar tantalum capacitor in series with microphone lead. You may get by with a .68 or a .47 mFd but anything less (.01, .005 etc) will not pass any speech audio worth listening to). The cap MUST be a non-polar. This will keep the D.C. from getting across the dynamic element while passing the speech audio through the cap into the mic preamp circuitry. http://www.heilsound.com/amateur/harmonics.htm#DC
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There is a dc blocking capacitor, so no damage will result.
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When you have an equipment source that supplies power (phantom power) to an elecret element -- everything is OK.
HOWEVER, IF you use other microphone elements (copper wound, magnetic bobbin, dynamic) -- then the DC power must be de-coupled. You use a capacitor to block this DC power. A 1 mFd. non-polar tantalum capacitor in series with microphone lead. You may get by with a .68 or a .47 mFd but anything less (.01, .005 etc) will not pass any speech audio worth listening to). The cap MUST be a non-polar. This will keep the D.C. from getting across the dynamic element while passing the speech audio through the cap into the mic preamp circuitry.
http://www.heilsound.com/amateur/harmonics.htm#DC
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