Christophers 66 Mustang Restoration and Modification

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    My home made Voltage Regulator works but I have an issue with the gas gauge reading a little low because the output is 5vdc.
A great Plug in Play ADJUSTABLE unit is here for $25:

  I plan on using this pre-made voltage regulator for my gas gauge and mounting it under the dash so I can adjust it without removing the gauge cluster:




This will also work for all of the gauges if you are looking to change out the Ford Factory voltage Regulator.
The new Instrument Voltage Regulator that came with the gauges died shortly after we installed it. I decided to use a solid state voltage regulator with capacitors to filter out the voltage ripples. It will be rock solid and never change like the old style does. The old case was used to hold the voltage regulator and act as a heatsink
Here are the parts for the IVR:

+5V Fixed-Voltage Regulator 7805
1 needed ($1.59)
10.0F 50V 20% Axial-Lead Non-Polarized Elect. Capacitor
Sorry for the poor quality photos from my BlackBerry












I tested the IVR and it put out a constant 4.98 volts DC all the way up to a 1 amp load.  I will put an inline fuse (2 amps) in the circuit in case there is a short. It will be accessible from under the dash.


Hope this helps you if you are looking to do a similar modification. I thought about putting everything inside the case but decided I was not concerned about making it look original. The heat from the regulator also will be a problem for the capacitors

5 dollars in parts from Radio Shack and it will hopefully last for the life of the car


Wiring diagram for 66 gauges:



Here is a simple schematic of the circuit. Note the center leg and the tab are both common and used for grounding. I opted to use the tab as ground and cut the center leg off. I felt that the ground being so close to the 12 volt in and the 5 volt out could be a problem.














The old IVR was gutted and the case was used as a heat sink for the voltage regulator.  A small hole was drilled in the bottom to mount the regulator. Note the 12 volt INPUT is on the left and the 5volt OUTPUT is on the right





20 gauge wire is soldered to each leg. Be careful to not to get the legs to hot with the soldering iron. Use a small pair of needle nose as a heat sink on the leg near the body of the regulator.




Heat shrink tubing is applied to each leg to insulate and strengthen them. The legs will break if you bend them to much! I found if you shape then and then use a heat gun they will stiffen considerably with the tubing and hold there shape.

  Heat sink grease is applied to the back side of the regulator (a little goes a long ways) and it is screwed into the case. The heat sink grease can also be purchased at Radio Shack.
  The wires are looped around and another small hole was drilled in the side. A zip tie was installed as a stress relieve for the wires to keep them from moving.

Another view with the Zip Tie cut off


 10.0F 50V  Axial-Lead Non-Polarized Capacitors are soldered to each lead. The other end of the capacitors is soldered together and will be connected to the case which is ground. Heat shrink tube is applied to all solder connections.


Connectors are applied to the ends of the wires. The 12 volt wire has the male spade connector and the 5 volt wire has a female connector.

More shrink tubing over the capacitors and a zip tie to hold the ground lead in place. Note the male and female spade connectors.











The ground ring connector will mount to the screw that holds the IVR in place on the instrument gauge.