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Re: AIDC 3733's on 12 volts



Most regulators want about 3 volts above the regulated voltage, if the
incoming voltage does not have too much ripple.

Gene Harlan - WB9MMM
Harlan Technologies - publisher of
OSCAR Satellite Report - OSR@hampubs.com
Amateur Television Quarterly - ATVQ@hampubs.com
http://www.hampubs.com


----- Original Message -----
From: "Mark L. Hammond" <hammond@surrealnet.net>
To: <BobsImsai8800@aol.com>; <amsat-bb@AMSAT.Org>
Sent: Thursday, January 31, 2002 12:27 PM
Subject: Re: [amsat-bb] AIDC 3733's on 12 volts


> How much "headroom" (volts needed for proper 12V regulation) does the 7812
> require?  Meaning, what is the "true minimum working" voltage that might
be
> supplied to the 3733 without modification to voltage regulator?
>
> Thanks,
>
> Mark
>
> At 11:39 AM 1/31/2002 -0500, you wrote:
>
> > >From K5GNA:
> >
> >I have modified some of my AIDC 3733's to run on the 12 volts right out
of
> >my IC 910H -- no power inserter needed.
> >
> >The internal regulator is a 7812, which is a 3 terminal 12 volt regulator
> >which powers the unit, but there is a separate internal 5 volt regulator
> >in the oscillator circuit.  With this second regulator, the oscillator
> >voltage (and frequency) are stable under any input voltages above 7 volts
> >or so.
> >
> >I cut the input and output leads loose on the 7812 and jumpered across
the
> >circuit to run it directly off the 12 volts straight out of the 910H.  It
> >works well, but since I don't leave it on all the time, it drifts a few
> >minutes when first turned on.  With the 7812 regulator in the original
> >circuit, it generates some heat and provides some thermal stability when
> >left on continuously.  Without the 7812 regulator, the unit is quite
> >stable during a satellite pass.
> >
> >73,
> >
> >Bob
> >K5GNA
>
>
> Mark L. Hammond  [N8MH]
>
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>

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