Rally dash gauge voltage. 5v or 6v nominal?

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Aussie Cuda

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I have a 68 Barracuda in Australia & I am fitting a variable DC supply to my rally dash gauges to fix a fluctuating reading problem.
I have been told that gauge design from the 6v days continued & the remedy was to just add the vibrator contact system to clip the 12 volts down to 6volts.
I also see a lot of reference to 5volt gauges in Mopar discussions
Can some one confirm the correct voltage setting for my supply output, please? 6 volt or 5volt.
Cheers, Glen
 
Glen, I prefer using the 6v chip. It's half of 12 and applying 6V is a good way to calibrate gauges so they see "half" of their reading. That's my opinion, I'm sure some will disagree. I've made a few instrument IVRs using 5V and 6V and they seem to work about the same, so it's probably a toss up.
 
RustyRatRod said:
Glen, I prefer using the 6v chip. It's half of 12 and applying 6V is a good way to calibrate gauges so they see "half" of their reading. That's my opinion, I'm sure some will disagree. I've made a few instrument IVRs using 5V and 6V and they seem to work about the same, so it's probably a toss up.
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I built a 5v for my ol Sat, out of the last Raido Shack in Tampa..and that was years ago... off topic I guess.. sorry
 
RustyRatRod said:
Glen, I prefer using the 6v chip. It's half of 12 and applying 6V is a good way to calibrate gauges so they see "half" of their reading. That's my opinion, I'm sure some will disagree. I've made a few instrument IVRs using 5V and 6V and they seem to work about the same, so it's probably a toss up.
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Thank you, Rusty.
I had initially set it to 6v, so I will go with that. The extra volt may help with any voltage drop problems, anyhow.
 
Aussie Cuda said:
Thank you, Rusty.
I had initially set it to 6v, so I will go with that. The extra volt may help with any voltage drop problems, anyhow.
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Well, this place has tons of opinions. Get ready for someone to disagree. lol It's one volt. Right? 6 always made more sense to me since it's half of 12. But what do I know? LOL Hope things are going well in roo land.
 
Aussie Cuda said:
6 volt or 5volt
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Yes!

One thing to look at is the current or wattage draw.

(Just using 100 ohms as a number)

5V/100ohms = 0.05A power = 5W
6V/100ohms = 0.06A power = 6W


The higher the wattage the farther the gauge will move. (The heater coil gets hotter and the bimetal bends more)
 
Dana67Dart said:
Yes!

One thing to look at is the current or wattage draw.

(Just using 100 ohms as a number)

5V/100ohms = 0.05A power = 5W
6V/100ohms = 0.06A power = 6W


The higher the wattage the farther the gauge will move. (The heater coil gets hotter and the bimetal bends more)
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So, in my warped mind, I would think a 50 worn, cycled bi metal spring would like an extra volt, to make up for years of wear?
 
RustyRatRod said:
Well, this place has tons of opinions. Get ready for someone to disagree. lol It's one volt. Right? 6 always made more sense to me since it's half of 12. But what do I know? LOL Hope things are going well in roo land.
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I agree to disagree if you agree with me!
 
Put it on a scope and then do the calculations!
:lol:

But seriously its kindof a square wave. Its a bimetal strip that heats up and pops open.
Power is supplies at 13.8 Volt to 14.9V depending somwhat on on rpm and temperature.
I don't know how much that effects the heating or if it matters at all because higher voltage => higher draw => heats faster => opens more quickly.

Here's a video I made showing the Voltage of the IVR output using a car battery for supply.
The gages are connected to resistors.
On the right is a Sun V.A.T. model CB set to the 8 Volt scale.

This test is with 2 resistors in parallel for the fuel gage. 11 Ohm or basically Full.
The other gages have a single 22 ohm resistor to ground, so mid gage.
Car battery supplying the power to the 12 volt pin connector.
In case you're wondering the background music is from Vietnam (from the guy in the neighboring garage).

Mattax said:
There's an MTSC booklet to go withthe filmstrip. Look through the www.mymopar.com collection for 1966 and years close to it for session 227.
Imperialclub's collection has a lot of broken links but is still a good index.

Gauge Cluster Issues/IVR
Scroll up in that thread to see the resistors used to simulate the sending units.

A lot of good info in this thread as well. Redfish knows this stuff.
Bench testing rally gauges
Click to expand...
 
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All 2nd gen cudas 67-9 had "rally dash" and the fuel gauge had the voltage regulator built into it. 12 V in to fuel and 5 or 6 out. Not sure if 5 or 6, sorry.
 
I have used both 7805 and 7806 regulators and have not seen much difference between the two.
 
"Rig it up" and test it.
1...There are known resistor "standards" for the 3 main gauges "points" L, 1/2, H These test resistances are "supposed" to be the same for all gauges
2...The fact that your senders may not provide those resistances does not change the fact that you need some place to start
3....There is a device you can buy for ?about 50 bucks called a "meter match." This is useful for correcting such as fuel gauge readings, but could be used on temp as well.

c-3826-jpg-jpg-jpg.jpg


The OTHER thing you want to do is to make sure that harness drop or other problems is NOT causing overly high system voltage---aka overcharge
 
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