[Mgs] 54 TF ammeter question

PaulHunt73 paulhunt73 at virginmedia.com
Sun Jan 18 08:50:46 MST 2015

Are you *sure* you reversed?  And didn't just put them back on the same terminals?  A typical ammeter and especially one used in a car of the era of the TF is a simple moving iron arrangement, in a coil with just two terminals.  Reverse the direction of the current in the coil and you reverse the magnetism, and hence the needle movement.  That's why ammeters work  - current flows one way to indicate a charge, and the other way to indicate a discharge.  Incidentally you could have done something else such that it was charging when you originally connected it, and now you have reversed it it isn't.  You need to confirm it *is* charging with a voltmeter.

  ----- Original Message ----- 
  From: dontoy--- via Mgs 
  To: mgs at autox.team.net 
  Sent: Sunday, January 18, 2015 3:24 PM
  Subject: [Mgs] 54 TF ammeter question

  Dear listers, 
  I have a 1954 TF which my father drove home from Pittsburgh in 1971. After an electrical problem way back then the ammeter got fried, along with damaging the temperature gauge. In an effort to go back to original I sent both units out for restoration to MoMa. I installed the temperature gauge first and it went up to 185* and held it there. That made me smile. Then I installed the ammeter. Since I had did the polarity switch (now a negative ground car) I wasn't sure which wire went on which terminal. I just guessed and put the brown with white on the left terminal, the solid brown on the right.  Of course upon starting the car, the ammeter ran in the negative side. 50% chance and I guessed wrong. So I thought. After reversing the wires I got the same result. I know I'm charging since I have never had a problem. I don't run a trickle charger and can start the car anytime in go out into the garage, even after months. Is this just one of the effects of switching the polarity or is there something I'm missing. I was showing a charge on the aftermarket unit that I was trying to replace. Ideas? 
  Don Toy
  " all great men are dead... And I'm not feeling well"

  Sent from Xfinity Connect Mobile App



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