MTFCA Forum

This VR came from a Model Ford Model A , but I am not sure about the voltage and or it is negativ or positive to ground .
Thanks for tour answer
Toon

The VR is essentially an ordinary diode cutout with a form of switchmode shunt regulation. To determine whether it's for positive or negative earth, simply test for the diode direction between the generator and battery terminals on the VR.
For example, if you were to connect a battery positive terminal to the generator terminal of the VR, and a light bulb between the VR's battery terminal and the negative terminal of the battery, and the bulb lit up, the VR would be for a negative earth car. Don't connect anything to the casing of the VR for this test.
Keep in mind Model A's are positive earth as standard, so there's a chance the VR is for positive earth unless the electrical system was modified.

Once you know the polarity, you can test what the voltage is with a current limited variable power supply fed into the generator terminal and see what voltage the crowbar circuit comes into action. It's going to get a bit technical beyond this, but I can give you more info if you want to PM me.

John Regan might be able to identify it looking at the bottom being's he made it ?

What you have appears to be a Voltage Regulator BUT it may have been modified. Note the open weld and the screw missing from the base.

Hi all ; To be sure what was in , I opened the [Regulator] and found a Diode .
The welds where NOT open .
Thanks for your answer .
Toon

From the information I have found that unit was made for cars the VERY seldom got driven, if it came off a Model A it has a diode for positive ground and will not work on a negative ground Model T.

Found another picture of the Fun Projects Cut Out 5055 for a Model T there is a difference in the base screws & rivets. Not sure if that is what distinguishes a T from the A model

Post on April 15 will tell how to ID voltage regulators: http://www.mtfca.com/discus/messages/17 ... 1302916449

So, it's just a diode cutout, not a regulator.