MTFCA Forum

I have a Jefferson coil tester with the power source missing. Can anyone tell me what was used to provide the 6 volts for
Testing the lamps and coil. I would think it would be a step down transformer? Did it uses rectifier?
Thanks for your input in advance.
Jim

6 volt lantern battey.

I don't know exactly what was used, but either a 6 volt auto battery or a stepdown transformer ought to work. A transformer with a 6-8 volt secondary would be suitable, and to test coils, it would need to be able to deliver about 2-3 amps at the secondary. Light bulbs don't care about AC or DC or polarity, but a coil will behave a little differently on 60 cycle AC as compared to clean DC, such as that provided by a car battery. An older battery charger with a 6 volt setting would provide 6-8 volts DC, probably a pulsed DC, rectified, but not filtered. The new type chargers usually have no 6 volt setting, and they use solid state regulation and safety features to prevent shorts and improper polarity connections. I suspect that they would not work well on a T coil. A full wave, filtered rectifier is a fairly simple device, but I don't know where you'd get parts today to build one.

If a lantern battery works, thats the ticket.

A
Four D cell batteries in series r its will work just as well.

How much current can a new size D cell provide?

This is out of a pieces/parts tester I picked up at Hershey several years ago, it has six leads coming out of it. I believe the two reds are 110v and the other four are six or twelve volt. I tried at that time to test it but kept blowing the fuse on my test outlet. I've got a couple of older doorbell transformers I might try instead. Jim
Measures about 2 1/2"X 3" and maybe 2" thick.

Here is a schematic I made when I restored mine.

 

It looks like the operational test applies 6 volts AC at 60 cycles. I assume the lamps are for continuity testing. The 18 volt tap is unused. It could be used to "high-pot" a coil to simulate operation on MAG.

Thanks for the diagram Bob. Jim

I want to thank you guys for the information regarding the Jefferson. Coil tester. I can see I am missing
A transformer of some sort. I think I will use a small transformer, maybe 6 /12 volt unit. I realize the tester
Is basically a go- no go device but I just wanted to restore it as a working novelty.
Jim-B

A transformer from an older 5 to 10 amp 6-12 volt battery charger would be a good choice. The crackerbox 6-12 V chargers used to be cheap, but I suppose that's changed. These newfangled chargers are so smart and safe they would probably shut down, take over your mobile device, and report you if you to federal authorities if you attempted to do anything out of authorized protocol with one.

If the bulbs are simply continuity testers, you could use 12 volt bulbs and then you wouldn't need the 3 volt tap.