Thread: Dash Gauges

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Any one here ever use those Runtz resistors to convert 6 volt dash gauges to operate with 12 volts?

I'm going to try and get the original gauges working in my uncles 48 F-1. Thought maybe someone here has been down this road already and could keep me out of any pitfalls.

I don't remember the name, but I had one on my 36 5 window and it had a 41 dash. I don't remember having any problems.

I'd think you want a Constant Voltage Regulator to give you a constant 6V regardless what your alternator is pushing. One unit can feed multiple gauges, and you can even get a kit to run your heater motor, too. Here's a source - http://vintageautogarage.com/runtz-voltdrop.html‎ I think the Runtz units are actually voltage regulators, but are for single feed, one per gauge?

Volt a drop is what I had and what Roger found is much better.

You can make your own voltage regulator circuit for about $.50 each.

1 - Standard Regulator 6 Volt 1.5 Amp 3 Pin 2+ Tab TO-220fp = $.35
1 - 10 uF 50 Volt Radial Capacitor = $.12
1 - 1 uF 50 Volt Radial Capacitor = $.09

7806T: MAJOR BRANDS: ICs & Semiconductors
R10/50: JAMECO VALUEPRO: Passive Components
RA1/25-R: JAMECO VALUEPRO: Passive Components

aren't those early gauges mechanical???except fot the lighting??


Back in early 60s when I put a later model Lincoln(well, actually an E475 Edsel,410 cubes 475 tq) and converted my 1955 ford to 12 volt, I changed the light bulbs and for the radio I put in a 6 volt feed from a sheetmedal screw into the center of the battery------------------

I agree with Jerry. Oil and Temp will be mechanical. Amp gauge doesn't care what the voltage is as its measuring amps. Only thing you'll need a resistor on is the fuel gauge.

Originally Posted by rspears

I'd think you want a Constant Voltage Regulator to give you a constant 6V regardless what your alternator is pushing. One unit can feed multiple gauges, and you can even get a kit to run your heater motor, too. Here's a source - 6 volt to 12 volt conversion parts, Ford flathead, Chevrolet 6 cylinder, Oil Temp Gas gauge reducers, 12 volts to 6 volt reducers, 6 volt alternators, 12 volt alternators, I think the Runtz units are actually voltage regulators, but are for single feed, one per gauge?

You are correct on both parts. Someone gave him the Runtz pieces so it's priced right.

Originally Posted by jerry clayton

aren't those early gauges mechanical???except fot the lighting??-

Originally Posted by HWORRELL

I agree with Jerry. Oil and Temp will be mechanical. Amp gauge doesn't care what the voltage is as its measuring amps. .

Nope, all electric... Already checked... I had to get a replacement for the oil and temp gauges as the originals didn't survive being connected to 12 volts.

Originally Posted by 36 sedan

You can make your own voltage regulator circuit for about $.50 each.

Thanks for the info! While I have the parts in hand.. I have a friend who may be interested in trying this on his own..

For about a buck total cost the regulator circuit can be made adjustable, so you can dial in the voltage to exactly 6.7 volts.

That's good stuff right there! I might be tempted to get the parts and assemble a couple.. just because, I wonder if they have a minimum purchase charge? I'll have to go check it out.

HERE'S a write up from over on HAMB.

Originally Posted by 49 Custom

Here's a straightforward way to build your own "Runtz" type voltage reducers so that you can use your 6 volt gauges on your 12 volt system.

The regulator is based on the LM7806 integrated circuit, which is able to reduce voltage while maintaining a constant current. Use one regulator for each gauge; this allows you to keep each circuit separate which is useful for sorting any troubles you might have. While it is possible to use one regulator for all gauges using a power transistor, it has a bigger footprint and produces more heat, requiring it to be carefully mounted away from any heat sensitive parts.

Here are the components:



1x LM7806 voltage regulator
2x 1μ 25-35 volt tantalum capacitors
1x Heat sink (around one inch long)
3x wires cut to 3 or 4 inches in length

You will also need a soldering iron, solder, some pieces of shrink tubing, and a bit of heat sink paste.

First, bend the leads on the capacitors into an "L" shape. Usually the longer lead is the positive side and since we want to attach the positive ends to the outer leads on the LM7806, make sure the capacitors are bent in opposite directions.



With the LM7806 sitting with the tab side down, solder one capacitor to one of the outer leads of the LM7806, then solder the other capacitor to the other outer lead. Again, be sure these are the positive ends of the capacitors. Carefully bend the remaining lose capacitor leads to make contact with the center lead of the LM7806. Solder them in place.



Next, trim the three posts on the LM7806 so they are just long enough to solder the wires into place. First solder the center wire (ground), then the left (12V) and the right (6V).



Cut some short lengths of shrink tubing and slide them along the wires all the way to the regulator side and heat them. Then take a larger piece and wrap the three leads together. This will both insulate the leads from each other and protect the connections.



Finally, put a dab of heat sink paste to the back side of the LM7806 and attach it to the heat sink with a screw.



When connecting them, select the appropriate connectors for your application. In the photo below, the red lead is connected to a switched 12V source (usually your ignition), the white lead is connected to the positive post on a gauge, and the black lead is connected to a ground.



Finally, attach your harness and reinstall your gauges!



Each voltage reducer cost about $3 and I learned a bit about how gauges and reducers work. Please don't hesitate to post questions and comments and I'll do my best to respond.

-Stefan

Thanks for the info 2MTC..

If you use the drawing I posted above with the 7806 reg that I suggested you will get exactly what toomany2count posted from the HAMB site, except for the heat sink, which probably won't be needed with the current draw of the gauge (though the heat sink is cheap if you want to add it). If you use the drawing I posted with the 7805 reg and lift the ground with 1k potentiometer (trim pot), you will get an adjustable regulator capable of dialing exactly 6.7 volts.

I used electrolytic capacitors as they are a little less temperamental than the tantalums, but either will work and the tantalums are smaller (just be careful with the soldering heat on tantalum caps).

Each regulator circuit is about a buck ($1.00) to build if you use the source I provided or others like it, Radio Shack will be 3 times or more. Some of the online sites have a minimum, if you are building several regulators for multiple gauges it should put you over most minimum limits. If not let me know and I can get them for you on one of my next orders, I buy in bulk so minimums are seldom a problem (I may have 7805 regs in stock, used to use a lot of them).

Originally Posted by 36 sedan

Radio Shack will be 3 times or more. Some of the online sites have a minimum, if you are building several regulators for multiple gauges it should put you over most minimum limits. If not let me know and I can get them for you on one of my next orders, I buy in bulk so minimums are seldom a problem (I may have 7805 regs in stock, used to use a lot of them).

PM coming your way.