Hi all,
As Tod noted, resistors used in the temperature sender or fuel tank sender
circuit can pull quite a bit of current and they should be appropriately rated
or else they'll get too hot.
I forget offhand what the minimum resistance in the gauge circuits is, but I
think that the maximum current can be on the order of 1/4 to half an amp. In
that case, a 4 ohm resistor would dissipate one watt (1/2 x 1/2 x 4 = 1). That
doesn't mean that a one-watt resistor is sufficient power rating, since that
power rating is typically obtained when the case temperature of the resistor
is 75 degrees C or higher (that's like 160 F or something). You should
probably use a 2, 5, or 10 watt resistor to keep the temperature rise under
control and prevent inadvertent burns or melting of other underdash parts.
Cheers,
Theo
________________________________________
From: tigers-bounces@autox.team.net [tigers-bounces@autox.team.net] On Behalf
Of Carmods@aol.com [Carmods@aol.com]
Sent: Thursday, October 21, 2010 7:06 AM
To: todbrown@roadrunner.com; tigers@autox.team.net
Subject: Re: [Tigers] Engine Temperature
Tod,
I have used a resister approach to calibrate the temperature gauge like you
did but I found that if I put shrink wrap on resistors it may burn off so
now I leave resistors exposed to air.
John Logan
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