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Percy/Jack, Lets not run too fast. You may not be able to power your device directly from the airplane system because if it is not a negative ground system internally and the "ground" side of the headsets are, it could provide a short to the plane's electrical system. The way to find out is to open the unit, determine which terminal on the battery is the negative one and while turned on and connected to the plane in the usual way, measure for voltage between the negative battery terminal and the airplane ground/earphone jack ground. There should be nearly none. If you are using a digital auto ranging voltmeter it is possible to read a few hundredths of a volt but nothing significant. If you measure 9 volts, your intercom is a positive ground unit and cannot be powered from the airplane system unless you use an isolated inverter. BTW, I have done this with one of those black 4 place intercoms which in fact was a negative unit. I powered it directly from the aircraft 12 volts without harm. It would be rare for a peice of equipment designed to run on 9 volts to blow up on 12 or 14 volts. Regards, Dick at www.hangartrash.com in sunny (most of the time) NM. ----- Original Message ----- From: "Percy Wood" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Wednesday, January 30, 2002 5:39 PM Subject: Re: [COUPERS] Intercom > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > At 07:05 PM 1/30/02 -0500, you wrote: > > >Any suggestions on what type of transformer I can used to wire the intercom > >into the airplane battery (12 to 9 volt transformer)? > > > >The ones at the local Radio Shack are all made for cig. lighter plug ins. > > A transformer will not work, Jack. They are for Alternating Current systems. > Your `coupe have a L-o-o-o-o-n-g extension cord on it? > Seriously, you need a voltage regulator. Or a series of diodes. Those are > available at the Shack. > Percy in Portland > ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiLm.aVzvvT Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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