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Old July 26th, 2006, 01:22 AM   #1
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using the power from "mic plug-in power" to run vibrator

Hi there, I'm working on a 35mm adapter for a Sony HVR-A1U and I noticed that the mic plug-in power jack has a voltage of 2.3. I was wondering if it would be possible to apply that power directly to a vibrator for the GG. I tried to hook the vib directly to the jack but it doesn't work so I figure it must be connected in a special way for it to receive the power. Can anyone help?

Thanks!
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Old July 26th, 2006, 07:33 AM   #2
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I wouldn't do that if I were you. Chances are you may already have fried something but don't take my word for it as I am no engineer.

Did you find 2.3v by testing with a meter or did you read that somewhere. If the A1U has a phantom power option, then the voltage will be higher when the phantom power is selected on, ballpark of 41v or so maybe??

Power available will be limited to that which a mike will use which will be low compared to the initial draw when a motor or vibrator is switched on.

Phantom power may be AC not DC. If its AC it is unlikely any DC motor will work off it.

Others with more wisdom than my pathetic fount will make more qualified and valid comment in due course.
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Old July 26th, 2006, 07:35 AM   #3
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I would just like to interrupt for a second, to point out to the mods that I *do* have some restraint ;)
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Old July 26th, 2006, 11:36 AM   #4
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To understand why this isn't working, you have to understand why phantom power is called phantom power in the first place. It's called this because it's invisible to balanced microphones; that is, the same DC voltage is sent through both lines. This means there is no potential difference between the two, so when you connect a regular DC appliance like a vibrator motor, nothing happens. There needs to be a potential difference between the two. Connect one wire to the negative port on your battery and you should see something happen.

I really wouldn't suggest delving into this route though, you could severely damage the preamp on your camcorder.
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Old July 26th, 2006, 02:23 PM   #5
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thanks for your answers!

Gentlemen, thanks a lot for your quick answers.

Bob Hart: I did found the voltage with meter, and also this is a different power output than phantom power, and is indeed DC, that's why I thought it could be applied into powering my little adapter.

Keith: I'm rather new here, so I'm not understading a word you're saying! If there's a way to see or read about the mods you've made, let me know.

Ben Winter: Just one question, where does the risk of damaging the preamp lie? I would think that applying that power to a little motor like a vib. would be no different than running a mic form it.
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Old July 26th, 2006, 02:39 PM   #6
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A preamp such as the one on your camcorder probably has no circuit protection. If the two wires touch, you're #$*@ out of luck and your preamp will probably be cooked if not your whole camera.

Are you using the XLR output or is there some mic power plug I'm unaware of? You can find the pinout of XLR phantom power fairly easily and get anywhere from 5 to 24v of power at 20mA current from the ground and one of the positive leads. This might be your best bet.

Last edited by Ben Winter; July 26th, 2006 at 04:10 PM.
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Old July 26th, 2006, 03:09 PM   #7
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the A1 also has a "MIC (plug-in power)" jack on top of the headphones jack, next to the lens. It gives 2.3v power. It's a regular stereo minijack in which power comes form both the tip and the ring. It's the red jack on the pic.

http://www.sundancemediagroup.com/ar...dphone_mic.jpg

I know this'll sound insane but I already had the two power cables touch (by accident) and nothing happened, so probably there is some sort of circuit protection.

Regarding your suggestion to create a potential difference by hooking one wire to the neg port of the battery, can you elaborate a little more on that?

Thanks a lot for your help, Ben.
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Old July 26th, 2006, 04:05 PM   #8
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Oh,
that is not phantom power. This is simply preamp power for an unbalanced microphone. The typical amperage for a small vibrating motor runs between 150 and 700mA; you probably won't see anything above 2mA coming from that jack. You'll have to look for power elsewhere.
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Old July 26th, 2006, 04:28 PM   #9
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well, guess i'll just have to add an external power supply for the thingie to run. Thanks a lot for your help!
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Old July 26th, 2006, 04:37 PM   #10
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Just because something has the right voltage, doesn't mean it can deliver the current.

You have to match both.

And the voltage you measure with a multimeter is the "open circuit voltage". which is not the actual voltage you'll get when you connect whatever to it.

If your application is really light duty, I guess it's ok. But a GG vibrator sounds dirty and power hungry.
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Old July 26th, 2006, 06:28 PM   #11
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Quote:
Originally Posted by Luis Bustamante
Keith: I'm rather new here, so I'm not understading a word you're saying! If there's a way to see or read about the mods you've made, let me know.
Welcome to DVinfo Luis. Keith is just making a little joke there, because "vibrator" can mean something else in English.... sorry, we're not going any farther with that, but I'm sure you can find someone to explain more fully :-)

And the "mods" Keith is talking about are the forum moderators (like me). So what he means is that he is resisting the temptation to make a bad sexual joke about the title of this thread, and he wants the moderators to appreciate his restraint (which we do :-)

And now we can return to the real discussion...
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