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Discussion Starter #1
In researching my guage problem, I ran across the article below on making a solid state constant voltage regulator:
http://www.turbotbird.com/techinfo/ivr/Default.htm
Does this make sense/seem like it should work? I'm just a mechanical engineer, who didn't do well in circuits 20 years ago, so any comments would be appreciated.


Carl
 

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Yes, it does make sense. Its not too difficult to do and someone spent some time thinking this out...I earmarked the site to copy and build one for mine...
 

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Discussion Starter #3
I bought the voltage regulator from Radio Shack (still stocked), but the 270 ohm resistor is no longer available. I'll look for another source.
After bench testing, the old CVR is good, the new CVR is bad (12v across correct terminals, no cyclic output, unlike the old CVR). Old CVR back in the dash got me my water guage back, meaning the old CVR isn't the problem.
Now I have to see if I can find an old CVR that I can butcher to try the solid state version out.
 

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circuit will work fine but his claim that a breadbox size unit was needed in the '60s is bull. Zener diodes were available and used by military equipment designers but few industrial engrs were aware of them or felt they were too expensive at $2 or so a piece. new VRs are only $26 or so from my Virginia Classic Mustang catalogue and unless you like to solder why not buy new one?
 

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You can always put two resistors in a series to get the desired resistance. A 100 with a 170 ohm or any combination would work :)
 

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Wouldn't a zener with a resistor on its tail generate a lot of heat thru the resistor?
 

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Discussion Starter #7
I can do the two resistors in series, but since I don't want the leads on the resistors to ground, except for at the tail, i'd rather try to keep it clean and use just one resistor.
I'm a little annoyed with MU, I'm working from last years catalog, price 24.95. I call up, guy says order totals $80 (add in $10 for the MC cover I also ordered). I asked, was told the CVR was up to $64, and let it go through. I've since found a couple of sources around $30, although the MU CVR is a Ford part. Shame of the matter is it turns out the old CVR was fine, new CVR is bad, so now I have to return it anyways.
 

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my only problem with this idea is that the 7805 is gonna get HOT
it needs more of a heatsink than just the little tin lid of the old cvr.
while your at Radio Shack ask them for a piece of heat sink material, its a chunk of aluminum with fins on it, bolt your 7805 to its flat surface and use heatsink grease for better heat transfer ,then attach the unit to the car, since its gonna set up under the dash where you wont know hot the little 7805 is really getting till its too late...
Remember the old cvr was not constant,the little points opened and closed continuously...or intermitantly...the new 7805 will be used in a constant-on state as long as the car is running and or the ignition key is on.
When you buy one the package will have ratings for the 7805 with PROPER heat sinking taken into account.
Its best to know the total amperage draw of all the guages your going to run from the 7805, all 7805's arent the same rating.
I havent measured the total amps (milliamps in this case), but someone surely has ? 150-300 mils each is my guess, so you need a 7805 rated no less than 1 amp ,more is better, and heatsunk properly.
Dont believe me? hook it up with out any heatsink, run the car for a while and see how long you can hold your finder on the 7805 .
my 2 cents
 
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