Temperature Gauge

[burner31]

Originally Posted by PRG999

Where does one connect the light switch power wire to on these gauges?

When I turn on my dash light my temp gauge liights up...so dash light

[CarlG]

I have mine connected to the tail light circuit, so that any time any of the lights are on, it lights the gauge. (I also have the dash light connected that way as well.)

[Ed in Maine]

I also was not satisfied with the temperature measurement for my Model A. My motor meter did not measure temperature accurately. I did some research on the internet and tried the following two schemes:
Measure Temperature with the transistor LM34. This semiconductor is tiny with three leads coming out of it. You can connect to it a resistor and a 9 v battery. Then with a digital volt ohm meter you can measure the millivolt signal coming from the transistor which is linear with changes in temperature (F) from -50F to 300F. It is accurate to ½ F. I used very small wire (24-26 ga.) wire and fed it out of the radiator in the over flow tube into the engine compartment, then behind the kick panel inside the car. I use it as a test device not as an operational temperature monitor because I never figured out how to shield the sensor from the RF from the ignition. The readout jumps all over when the engine is running!
Measure Temperature with the Taylor Digital Thermometer #3516. This is the kind of digital thermometer that you use to measure the temperature of a roast beef. It disassembles easily so that you can mount the circuit board and digital read out into a Motormeter. They are less than $10.00 and are very accurate and while the read out is small it can be seen from inside the car. The Problem: The thermometer has an “auto off” feature which turns off the thermometer after 10-15 minutes. You have push the On button again to turn it back on. I couldn’t figure out how to defeat this feature and no one at Taylor Instrument could tell me either. Maybe someone at Ford Barn could figure out a fix. I enjoy playing with little projects like this. Ed

[Badpuppy]

I like your LM34 idea (LM35 for Centigrade offset). Try using 22/2 shielded wire -

https://www.alliedelec.com/belden-84...RoC72EQAvD_BwE

Unshielded wire makes a great antenna. Connect shield between +Vs and chassis ground, one wire between -Vs ("ground" pin) and -6V battery, and the other to the resistor connected to -6V. You may have to run several loops from the battery supply through a ferrite bead to quiet it down.

[PRG999]

Thank You

[Badpuppy]

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Just realized a problem with my suggestion - the shield currents will probably affect the circuit operation quite a bit. Shield should be grounded at one end only to be most effective, which means use a 24/3 shielded cable -

https://www.showmecables.com/catalog...8aAirFEALw_wcB

The 9V battery is a good idea too, since it won't introduce any electrical noise, and should last forever with that load.

[Ed in Maine]

Badpuppy, Thank you for your suggestions for the LM34 transistor temperature measurement. Ed

[Dave1929]

I bought an ARCO temp gauge from Snyders. After installation I figured out that it was reading 60 degrees too low. I called Snyders and they promptly sent me another gauge. The new one didn't work at all. So two gauges in the trash, $49 down the tube and one $17 temp gauge from Harbor Freight I have a good working temp gauge. I will always have a working temp gauge.

[pbishop]

I bought a Sunpro gauge and placed it at the bottom of the instrument panel. It does look a little odd, but I can see it with a glance and that is a great comfort. I still have the motor-meter on top of the radiator - it just looks SO great with the 'wings' underneath.

[Bob-A]

I always run an original Moto-Meter and they work for me.


Bob-A

[Benson]

Originally Posted by Ed in Maine

I also was not satisfied with the temperature measurement for my Model A. My motor meter did not measure temperature accurately. I did some research on the internet and tried the following two schemes:
Measure Temperature with the transistor LM34. This semiconductor is tiny with three leads coming out of it. You can connect to it a resistor and a 9 v battery. Then with a digital volt ohm meter you can measure the millivolt signal coming from the transistor which is linear with changes in temperature (F) from -50F to 300F. It is accurate to ½ F. I used very small wire (24-26 ga.) wire and fed it out of the radiator in the over flow tube into the engine compartment, then behind the kick panel inside the car. I use it as a test device not as an operational temperature monitor because I never figured out how to shield the sensor from the RF from the ignition. The readout jumps all over when the engine is running!
Measure Temperature with the Taylor Digital Thermometer #3516. This is the kind of digital thermometer that you use to measure the temperature of a roast beef. It disassembles easily so that you can mount the circuit board and digital read out into a Motormeter. They are less than $10.00 and are very accurate and while the read out is small it can be seen from inside the car. The Problem: The thermometer has an “auto off” feature which turns off the thermometer after 10-15 minutes. You have push the On button again to turn it back on. I couldn’t figure out how to defeat this feature and no one at Taylor Instrument could tell me either. Maybe someone at Ford Barn could figure out a fix. I enjoy playing with little projects like this. Ed

You might try a length of Ethernet twisted pair cable. Strip off plastic shield, inside are four twisted wire pairs

Or leave cable shield intact for run near engine and run one pair up overflow tube as copper tube shields any noise from wire inside.

FWI the pairs of twisted wires change direction every foot of so ... Purpose is to reduce interference. So be careful removing sheilding to not disturb wraps.

Category 6 cable has better noise rejection as it has more twists per foot than Category 5.

Might be worth a try!