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Reply-To: "Ralph Naylor"
From: "Ralph Naylor"
Subject: Re: Need idea for a remote lamp status indicator.
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Wed, 08 Jan 2003 21:51:43 GMT
NNTP-Posting-Date: Wed, 08 Jan 2003 16:51:43 EST
"Glenn Ashmore" wrote in message
> I am working up a design for a MOSFET based switch box to control the
> lights on my boat's mast from the cockpit. These lights cannot have
> more than a 3% voltage drop from the battery so wire runs have to be as
> short as possible and the run up the mast and back to the switch box is
> 130' long. The switch box will eliminate about 50' of wire from the
> mast to the cockpit but there is a drawback.
> From inside the cabin I can't see the switch position or the lights. I
> need a circuit design that will light an LED on the switch box when the
> light is on. Because of the possibility of a burned out bulb or broken
> wire the circuit has to know that current is actually flowing and not
> just that the MOSFET is on. The circuit must also have minimum effect
> on the power reaching the light.
> Specifics: The voltage is 12-13.8VDC and the load ranges from 2A to 7A
> depending on the light. The MOSFETs are 30 amp IRFZ34 driven at close
> to max Vgs.
> Glenn Ashmore
> I'm building a 45' cutter in strip/composite. Watch my progress (or lack
> there of) at: http://www.rutuonline.com
> Shameless Commercial Division: http://www.spade-anchor-us.com
Allegro used to have a chip intended for monitoring automotive lamps. I've
waded thru several searches on their site w/out finding it. IIRC, it was a
4-channel pass-thru with four separate alarm outputs, and you could parallel
external shunt resistors for heavier loads. Back when I had more hair and
less kids I marketed an inexpensive running light monitor using it. The
near-universal response was "Why should I care if one of my running lights
Ralph in NH
Building a D4 out of scrap wood
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