DANMAS@aol.com wrote:
>
> In a message dated 98-12-18 13:47:29 EST, peterz@merak.com writes:
>
> > Recently, the topic of using an electric oil pressure gauge (to replace a
> > mechanical one) was discussed. Looking at a "sample" gauge wiring diagram
> in
>
> If the gauges are of the dual coil variety, there will be three connections -
> 12 volts, ground, and sender. On the TR6 gauges, there are only two
> connections - 12 volts and the sender (if there is a ground connection, it is
> for the illumination lamp).
I don't know the diagram in the Holden catalog, but perhaps this would
be helpful--the Jag electric oil pressure gauge previously described is
case-grounded, so it is a dual-coil unit, which would likely mean there
is some voltage compensation. Additionally, I think, most 12v gauges
operated by senders have some damping because of sender
behavior--contrast the behavior of a voltmeter to a gauge operated
through a sender--voltmeter needle response is very fast, since it's
essentially operating through a shunt--variations in voltage level show
up very quickly. Senders have to adjust to physical changes which are
translated to electrical resistance. Even when oil pressure drops
suddenly, the large changes occur over hundreds of milliseconds, enough
to show an indicated smooth change in needle position.
Cheers.
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