I made one like BB did. If done right they will hold rock solid for around 6 or 7 bucks. But to have as many problems as you did there may be something else wrong. Was your new regulators grounded properly? There should be no paint where you are mounting it, this would be your ground. Try disconnecting everything from the 5 volt output. Turn the key on, you don't have to start, measure the output. If it measures a good 5 volts connect one unit up at a time, gas gauge, oil and temp. See if any one gauge makes the 5 volts go haywire. Haywire is a high tech term meaning things going wrong. Try a few checks before replacing again. But as I said before the listing BB gave you works well and is adjustable. 

wsinsle wrote:

measure the output. If it measures a good 5 volts 

If the bi-metal regulator is  working, it will not  put out a "good 5 volts".  it will show a flucuation from around 4 to 7 butt (TS&T) only on an analog volt meter (that's one of those old timey meters with a needle that  swings from zero to whatever scale it's set at).  The new super  whizzy DVOM won't swap ends quick enough to give a very good reading on a bi-metal CVR....at least that's been my experience.

Just for grinns, I just went to the shop and heated up a known good bimetal CVR.  It's know good 'cause it came out of our 66 and with a  static 12.58v from a fresh battery it reads from just below 1 to nearly 5v and the DVOM.  I couldn't find my old timey Simpson but as I said, I seem to recall that they will flop from around 4 to 7.

Reason for this, for you all digital crowd, is that the bi-metal CVR acually puts out full battery voltage (say 13.5V) then Zero, then bat volts, then Zero and  the  instruments get the average and are constructed so they don't move quick enough to try to follow the momentary voltage swings.

With my new solid state CVR on the bench, I had it adjusted to just under 5V to have the gas gage at the  E mark with 75 ohms to ground (Stock gas gauge spec at empty).

BB

Last edited by Bullet Bob (9/11/2013 5:48 PM)

a test lite will show exactly what BB is explaining. It will blink on and off with every pulse. I just put a Ford regulator in mine and that is exactly what it did. The digital meter could not give a good reading. The regulator i used is from a newer pickup and has terminals like a 9 volt battery. I soldered the connections from an old radio to some terminals and plugged in that way. I did order an adjustable regulator for the gas gauge. Mine still does not read correctly.

Bullet Bob wrote:

I think this is the best answer...and it's adjustable.
http://www.circuitstoday.com/25-v-adjustable-regulator-using-lm117-ic

That will work, but it's a 1.5 amp unit.  The LM138 is very similar, but will provide 5A continuously.   This IC will run cooler and provide more "headroom" to keep the gauges from drifting with varying load.

http://www.ti.com/lit/ds/symlink/lm138.pdf

John
 

Bullet Bob wrote:

John wrote:

Bullet Bob wrote:

I think this is the best answer...and it's adjustable.
http://www.circuitstoday.com/25-v-adjustable-regulator-using-lm117-ic

That will work, but it's a 1.5 amp unit.  The LM138 is very similar, but will provide 5A continuously.   This IC will run cooler and provide more "headroom" to keep the gauges from drifting with varying load.

http://www.ti.com/lit/ds/symlink/lm138.pdf

John
 

Much better, John.  Thanks, I may just upgrade mine before install.  However, there are a number  of these out there an  no reported problems....so far. 

Have you calculated what the inst. ckt on a 66 pulls?  I may spend a few minutes with  the ohm meter and find out, just for grins.

BB

I have not..  They probably don't draw that much, but when you are building one unit, the cost of the IC doesn't matter to upgrade.  If you're building a million of them, then if the higher amp units are .50c more, it matters.

Kind of unrelated but interesting,  I do know the ammeter (not powered by the CVR) pulls three amps in either direction, but true ammeters are very low impedance units.

John

Edit:  duh.. I have my instrument cluster at my shop.  I'll check each gauge individually and report back.

Last edited by John (9/12/2013 4:11 PM)

wsinsle wrote:

Thank for education BB.  Another thought is to buy a straight 5 volt regulator from the shack. For a buck 99 it's a cheep way to get up and running and not much soldering.

Problem with a fixed 5V is that nothing is "standard" on these old cars.  Then you throw in the crappy QC on the aftermarket fuel sender and, well...an adjustable CVR just makes  more sense if you want the fuel gauge to mean anything.  The Oil and Temp can be arbitrary but the Fuel ought to mean something.

BB