AV video camera input

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justtrev
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AV video camera input

Post by justtrev » Wed Sep 08, 2004 3:58 pm

I have fitted a miniature tv camera to my motor cycle and route the video signal via the a/v inputs to an on an onbard digital VCR.
I cannot work out what type of microphone [and circuit] will capture sound for input to the red
and white leads for the AV input. Can anyone direct me please....
thanks....<p>Trevor.

Mike
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Re: AV video camera input

Post by Mike » Wed Sep 08, 2004 5:08 pm

You need a dynamic mic otherwise you will need a preamp.<p>Also, mics are mono so you will need a splitter.<p>Instead of buying a mic, a standard speaker (single driver, smaller is better) will work as a mic also.

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Chris Smith
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Re: AV video camera input

Post by Chris Smith » Wed Sep 08, 2004 5:24 pm

The manual should give you your specs. Each is different.

Dean Huster
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Re: AV video camera input

Post by Dean Huster » Thu Sep 09, 2004 4:12 pm

I disagree, Mike. The A/V jacks on a VCR are line level audio, and as such, will expect levels on the order of tenths of a volt while a dynamic microphone output is in the order of millivolts. You'll need a preamp for a dynamic mic or a speaker -- and don't forget that speakers are often lousy for flat frequency response when used as input devices.<p>A crystal microphone, which is a lot harder to find these days, would probably work better without a preamp. You might find crystal mikes associated with old tape recorders at flea markets.<p>Dean
Dean Huster, Electronics Curmudgeon
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jwax
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Re: AV video camera input

Post by jwax » Fri Sep 10, 2004 3:33 am

A clip-on microphone for a PC ought to work. Add a "Y" cord to drive both audio channels if the recorder has stereo inputs.

ad5mb
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Re: AV video camera input

Post by ad5mb » Fri Sep 10, 2004 8:19 am

http://www.supercircuits.com/store/prod ... 3&mitem=21<p>I eliminated the flaky connector, soldered the wires directly to the board<p>[ September 10, 2004: Message edited by: ad5mb ]</p>

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Re: AV video camera input

Post by toejam » Fri Sep 10, 2004 9:11 am

does the on board digital recorder have a mic input?

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Re: AV video camera input

Post by Dean Huster » Fri Sep 10, 2004 9:20 pm

I've always assumed the PC mics were electret, requiring a phantom dc supply.<p>Dean
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jwax
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Re: AV video camera input

Post by jwax » Sat Sep 11, 2004 5:07 am

Correct, Dean. I'm assuming the recorder would accomdate an electret- but don't know. :confused:

paulrevelcet
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Re: AV video camera input

Post by paulrevelcet » Sat Sep 11, 2004 7:23 am

Try this web page for some info on line level ver. mic level.<p>http://www.epanorama.net/circuits/line_to_mic.html

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Re: AV video camera input

Post by Mike » Sat Sep 11, 2004 3:15 pm

Dean, one question,<p>I was able to plug a speaker into the cd input of a stereo reciever, and get very loud volume, same loudness as a cd would at that volume level

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Re: AV video camera input

Post by Dean Huster » Sat Sep 11, 2004 5:42 pm

Mike, I'm sure you're correct on that. It's been a long time since I've used a speaker as a microphone. Since the general theory of voltage generation in a speaker and a dynamic mic are the same, I was saying that the voltage output is the same. Now that I think back to when I was a kid and playing around with some old 10" speakers from some old TVs, I was shoving that signal into the crystal mic input of the tape recorder, so the level had to be higher. A 10" speaker (and smaller ones for that matter) push the voice coil a l-o-o-o-ng distance through the magnetic field compared to what a dynamic mic would do, and generating a proportionally higher voltage. Ergo, the speaker should work on a line level input, especially if that line level input were that of an audio tape recorder where you could compensate a bit for overall level differences.<p>Thanks for shaking up my (poor) memory!<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

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