Amp Gauge ?

[55 Fargo]

Just came back inside, tested both water temp gauge, using an electric sending unit, some hot water, worked well on the 12 volts, gauge and sender check out, fuel gauge will peg if momentarily grounded, last time was able to use an old GM sender unit, and got it showing different graduations on the gauge. All tests were conducted with 12 volts.

I will to be on the safe side use a CVR or something to avoid burning out the gauges.

Now I know others have used 12 volts on the earlier 2 wire fuel gauges with success without any voltage dropping devices. I have no idea if the 2 wire fuel gauges are more tolerant of higher voltage, than the 1 wire 6 volt gauges, I do not have any personal experience on this front to draw from...

[Plymouthy Adams]

actually Fred..the CVR of Ford/Mopar design is a pulsating voltage as it is but a bi-meal regulator....and the Runtz as shown in the link above IS of a constant voltage as it is a voltage controlled device by use of a zener diode..one can make their own and I have done so in the past..I have repaired bi-metal CVR's by popping the case and enclosing the zener diode and current limiting resistors..the pulsating voltage is perfect really as the slow acting movements read rad steady with the pulsating voltage and actually allow a more solid needle as the gauge has to respond to the pulse voltage...slow to rise..steady..slow to fall...

Fred..the early two wire units have each coil going to ground and split between the resistance of 0-30 as determined by the wiper position...PLUS they have their own 5 volt built in bimetal voltage regulator...

Edited December 3, 2013 by Plymouthy Adams

[55 Fargo]

actually Fred..the CVR of Ford/Mopar design is a pulsating voltage as it is but a bi-meal regulator....and the Runtz as shown in the link above IS of a constant voltage as it is a voltage controlled device by use of a zener diode..one can make their own and I have done so in the past..I have repaired bi-metal CVR's by popping the case and enclosing the zener diode and current limiting resistors..the pulsating voltage is perfect really as the slow acting movements read rad steady with the pulsating voltage and actually allow a more solid needle as the gauge has to respond to the pulse voltage...slow to rise..steady..slow to fall...

Fred..the early two wire units have each coil going to ground and split between the resistance of 0-30 as determined by the wiper position...PLUS they have their own 5 volt built in bimetal voltage regulator...

Thanx Tim, I have a 1 or 2 of the dash plug in CVRs around here, but yes I have tested it before, and it pulsates. The link you attached seems like a decent item for this task.

[Plymouthy Adams]

It seems every time this comes up folks think the standard Runtz resistor is the answer for the gauges and to me that is the farthest from the truth....A CVR designed for this or the solid state unit is far superior and prevents surge....