1940 Ford Deluxe Voltmeter for 12 Volts

C

Capuano

Member
I am changing my 1940 Ford Deluxe from 6 to 12 volts. This year car uses a volt meter rather than an ammeter. I can not use a RUNTZ 12volt to 6 volt reducer for this voltmeter. Called Don Baxter about alternatives. He said he had no alternative for my standard voltmeter. Does anyone have an alternative keeping the same appearance voltmeter or do I need to change all my gauges in my instrument panel? :confused:
 
Since you worked with elevators, you must be familiar with electricity so all you need is a series resistor at the meter plus terminal. The value of the resistor can be calculated by ohms law and a few measurments but may be much easier to determine by trial or a 10 turn helipot.
 
Yep. A 55 to 60 ohm resistor in series with the meter will work. I used a 10 watt rated resistor on the pickup. It has a deluxe gauge panel.
 
A place like Williamsons in Arkansas may be able to recalibrate your original gauge to work with 12 volts.
 
I had Williamsons in Arkansas rebuild my gauges 25 years ago. He put a resister in line with the volt meter, and it works great. I used a voltage reducer on the rest of the gauges.
Dave
 
I used a variable resistor to set the gauge at the top of the red bar with just the ignition switch on, I started the car and watched to see if the gauge went into the green band, it did. Then I turned on all the lights and the heater to see if the gauge went into the yellow band, it did. Then I measured the resistance of the variable resistor to see how many ohms it was, I then bought a resistor of that value and installed it on one of the gauge leads and It always worked perfect. Good luck
 
Capuano said:
I am changing my 1940 Ford Deluxe from 6 to 12 volts. This year car uses a volt meter rather than an ammeter. I can not use a RUNTZ 12volt to 6 volt reducer for this voltmeter. Called Don Baxter about alternatives. He said he had no alternative for my standard voltmeter. Does anyone have an alternative keeping the same appearance voltmeter or do I need to change all my gauges in my instrument panel? :confused:
Click to expand...

Here's how I used a 60 ohm resistor to get original 6V voltmeter to read correctly when converting to 12 V. In this set up I used a Ron Francis CVR to reduce the 12V so I could still use the original 6 V gauges. However, the BATT gauge must be isolated from all the other gauges using the 60 ohm resistor. The good thing about the CVR is that your FUEL gauge will still work with the original gas tank sending unit. Thanks to Flat Ernie for his help.Read post #6.
http://www.fordbarn.com/forum/showthread.php?t=48622&highlight=1940+ford+12+volt+conversion
 
Last edited:
Dah on my part. Thanks for the all the responses. It is appreciated and makes sense. Glad you guys out there with experience can really help.
 
Last edited:
I THINK if you measure the resistance of the volt meter and get a resistor
of that value and parallel the resistor with the volt meter it will read half
the voltage. G.M.
 
Replies such as these plus input from guys like Bubba and Uncle Max in their fields
of expertise are worth...............how much...........can't put a price on it. Thank you
Ryan for keeping this site afloat !!
Charlie ny
'Ol Ron, G.M., Walt Dupont, Mac Van Pelt to add just a few more
 
Charlie ny said:
Replies such as these plus input from guys like Bubba and Uncle Max in their fields
of expertise are worth...............how much...........can't put a price on it. Thank you
Ryan for keeping this site afloat !!
Charlie ny
'Ol Ron, G.M., Walt Dupont, Mac Van Pelt to add just a few more
Click to expand...

If it were not for guys like those named by Charlie ny, and many others who have helped this neophyte out on many occasions, I would just be driving modern iron, which is not half the fun. Thanks for all the help received on the Barn, from "All Y'all". Lawson
 
Apols for digging up an old thread, but I have to ask: why can't you use an isolated solid state converter for the voltmeter?

My understanding is the solid state units simply provide a consistent 6V drop across them regardless of load.

I'm not questioning the logic of the resistor - what am I missing?
 
fortyonerag said:
Apols for digging up an old thread, but I have to ask: why can't you use an isolated solid state converter for the voltmeter?

My understanding is the solid state units simply provide a consistent 6V drop across them regardless of load.

I'm not questioning the logic of the resistor - what am I missing?
Click to expand...

I think your understanding of modern electronics is a bit higher that the average of the members here. Sounds like a good idea, though; they're cheap enough these days. If it was me, I'd get one and try it.
 
fortyonerag said:
Apols for digging up an old thread, but I have to ask: why can't you use an isolated solid state converter for the voltmeter?

My understanding is the solid state units simply provide a consistent 6V drop across them regardless of load.

I'm not questioning the logic of the resistor - what am I missing?
Click to expand...

Isn't the solid state units attempting to maintain a consistent 6v? Doesn't that defeat the purpose of a voltmeter? You are wanting to see the variations in voltage, not look at a meter showing you a constant reading as the voltage varies. Once the voltage dropped below some level it would not be able to correct for it, but what you end up with is an idiot light, on or off.
 
I think I see your point. If your 12V system drops to say 10V, the 6V meter will 'see' 4V.

Dropping to 8V, the 6V meter will 'see' 2V. Not exactly linear indication. More like a good/bad indication - idiot light.

Once the 12V system drops below say 6v, there will be nothing on the meter, but of course by this time the situation is code brown anyhow.
 
You must log in or register to reply here.
Back
Top