Will be redoing the Dash on a 68 Barracuda and will be converting the Instrument Voltage Regulator to Solid State per the November 1992 Mopar Muscle Article.

Most of these conversions use a "7805" voltage regulator which supplies a constant 5V to the gauges. My question is WHY 5V? These gauges are meant to run on 6V so why not get a "7806" voltage regulator instead?

I have heard that people using the 7805 dont get full gauge travel and accuracy. Wouldnt a 7806 therefore be the answer?

Also I have seen some people soldering the additional Capacitor (which is meant to protect the Voltage regulator from spikes) to the 12V input side of the Regulator, and other people soldering it to the 5V output side of the Regulator.

The Mopar Muscle article shows it soldered to the Output side and to ground. This doesnt make sense since it will have no way of protecting the Voltage Regulator since they mounted it "downstream" of the current.

THANK YOU

Here are two links showing different Capacitor configuration:

http://1962to1965mopar.ornocar.org/ml-instrument-voltage-regulator64.html

http://www.jefframin.org/library/IVR.2.jpg

Not sure what the original gauges were designed for, but I could never get the 5v regulator to read full scale, so you might be right on the need for 6V.
You do need to consider the current rating of the regulator, some are too low.

Protection cap at input makes sense, wouldn't hurt to have another on the output as well, for ripple suppression.

I figure by using a 6 V Regulator, I can calibrate the needles at the half way point with 2 AA batteries (3V)

when I test the gauges with 3V they go to half way (give or take 1/16") I can bend the needles as needed so that they all go to precisely half travel at 3 Volts.

I know the parts aren’t that expensive, I’ve built a few to the specs in that article. Would be interesting to see the results of both 5 and 6 volt.

Does anybody know what voltage the Real Time Engineering regulator run at?

why not 6v

Check what .5 volt diff makes

http://www.dodgecharger.com/forum/index.php/topic,37999.0.html

FWIW when I bench checked mine they were exactly halfway with 3 volts.

Just an FYI.
Some years back I bench checked a few factory IVR's using my Fluke 179. It has a ability to average readings over time.
The voltage output of the "point style" IVR will start at 12 volts when first powered up then it will go to 0 volts when the points open. The points close again and the it's output goes back to 12 volts. With in a second or two the points will be opening and closing at a very rapid pace. Way too fast for the meter to read in real time.
I switched the meter setting to average reading over time and found that the IVR was outputting and average voltage of around 4 volts. I was a little surprised that it was not closer to 6 volts. I tested the other IVR's using the same method and found the same results.

The factory IVR s a thermal resistor, it won't work well with the minimal load of the Fluke.

The factory IVR is not a thermal resistor, it is a bimetallic strip that heats and cools cycling the output on and off causing a chopped DC output that averages somewhere around 5V.

I guess if you looked at the output on a oscilloscope you would see a square wave form.

How many gauges are you powering, Temp, Fuel, and oil?

The reason I ask, is if all three, the linear IVR (7805) can go into thermal shutdown unless it had a good heat sink.

The 7805 regulator circuit should have both input and output capacitors.

Is there a picture of one of these electronic conversions completed? My dash does not work and I am pretty sure this is the reason. I would like to replace the old point type with a newer electronic version.
OOPS!
Never Mind. I just found th elink already posted back a few pages.

Why doesn't anybody say anything about Real Time Engineering plug, and play regulator, instead of having to rig something up?

Could it have anything to do with the high price maybe.

I'm wondering what's wrong with the factory regulators.
Has anyone ever really had 1 go bad AND destroy the gauges?
Not really seeing the benefit of paying so much for the solid state version.

While my dash is out, I figured now is the time to do it. It cost $10 (CDN) to make it myself.
Also the A body rally dash doesnt use a seperate plug and play regulator. Its integral to the fuel gauge. I ended up clipping out the regulator parts inside the Gas gauge and rigging it up externally. I ended up using the 5V instead of 6V per Nacho's link. I will test it at school next week and see if I can use their fancy equipment to calibrate them.

$50 is a cheaper than getting the gauges fixed, and they are designed so that if it fails, the power to the gauges are shut down.

Not me, but yes know some and have dissasembled many other clusters damaged because that. Any fail able to keep stuck the points burn the gauges. Even a missed ground which still with a good conditions VL will make the bimetall never to open and feed straight 12v

Dunno if this could be "promotional" to their product, but seems to be kinda logic