I like the RTE setup. Really a better design, but $50.

The linear regulator I pictured, is mounted inside the original IVR case, and the heat sink bolted to the outside of the case, with heat sink grease between the regulator, case, and heat sink. Not the ideal configuration, but with the stock case it plugs in like the original IVR (no soldering to the instrument panel.)
The regulator I pictured is a slightly better 1.5 Amp 7805 regulator, but that was many years ago. I haven't looked recently if there are even better versions now?

I think on my '69 rallye dash, each gauge pulled about 1/4 amp at full scale. Without the heat sink, at 3/4 amps (worst case - full tank of fuel, maxed oil pressure and water temps), the regulator will start to go into thermal shutdown (reduced voltage output) after about 10-minutes (depends on ambient temp.)
At 1/2 amp, I did not see any voltage drop without the heat sink, even after several hours. I think if you just have fuel and water gauges, just using the stock IVR case as a heat sink should be OK, but with all three gauges, the additional heat sink may be needed? I did not have a way to increase the ambient air temps when testing, and I din't know how hot it gets under the dash in the summer time?

On the other hand I almost never have a full tank of fuel, 100 psi oil pressure and 260 F water temps, so the real load is much less than the 3/4 Amp max, but the regulator needs to handle that situation to make sure the gauges don't read low when they should be reading high.

Really, if you have the money, just get the RTE regulator. If on a budget, the 7805 setup works OK but know its limitations.

If you need the 7805 regulator and caps, I still have some extras.

Tech archives

http://www.moparts.org/Tech/Archive/elec/11.html

Man I forgot about this as I read it back then. So I went looking through my stuff this morning and found a pair of NTE960. Yep they are 7805 with new heat sinks. Boy do I love free upgrades.

One of the reasons for the 5vDC regulators was that they are used in computer power supplies and are available cheap.

What's interesting to me is the idea that when car manufacturers switched to 12 volt systems they threw a voltage "regulator" at the dash instead of changing the gauges.

R.

Given a set resistance of the gauges, using 12V instead of 5V would almost triple the current drain.

Not to mention the reason it was done. System voltage varies alot. By using a regulated 5V which is well below any normal system voltage variance you can make sure the gauges read correctly regardless.

Actually the 5 volt IVR the factory uses came out way before any computers were on cars. Unless you mean any computers other then on cars ? Ford also used this setup as I don't know why they decided on 5 volts other then that's the best for the type of factory gauges that use a bi-metal strip that bends to move the needle. The voltage on them gauges has to be steady or the voltage changes just from the charging system with the car running would make the gauges move around. Now GM used magnetic type gauges that uses 12 volts to them and they use to wound coils to move the gauge as one coil is grounded and the other goes to the sending unit so it varies how strong it is to pull on the needle and move the gauge. I don't know which are better but you can tell when cars had the GM type magnetic gauges as they usually will stay where they are when the key is turned off and of course the Mopar and Ford type bi-metal gauges go back to zero or empty when the key is turned off. Ron