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Receiver Magnets

Started by JimNY, March 10, 2023, 02:40:25 PM

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Sorry if this question has already been asked and answered. I have a pretty nice ABT long pole receiver that sort of works. When hooked up sound is heard but it is very low. I also noticed that the magnets don't attract the receiver element very well. I'm jumping to the conclusion that the bar magnets have lost most of their power over the past 125 years. Assuming that is the my issue, I'm looking for some advice on how to re-magnetize them (if it is even possible).

Thanks in advance!


this guy shows his DIY magnetizer for magneto ignitions on very old engines. Magnets in receivers and telephone magnetos are not different.
Some folks also had luck just adding a tiny neodymium magnet in the right way.
In a French receiver I once found that the 2 magnet laminations were assembled in the wrong way. Their magnetism subtracted instead of adding up. Flipping one of the magnets over solved the problem.


Thanks for the info countryman.
I viewed the video a few times and finally decided to  simplify things by just wrapping a coil of wire around each magnet making a simple solenoid. Then I attached a 12v DC battery for a few seconds. The trick was to get a strong enough battery.  I started with three 6-volt lantern batteries in series but there wasn't enough current. Luckily I had a an old car battery in the garage that still had more than enough amperage to do the trick. A few touches to the battery posts was all it took. I am happy to say my long pole is back in good working order!


Could you explain or tell us how you determined the existing magnet polarity (magnet field), the direction of the wire winding in that field, the wire gauge, the number of windings, which ends of the coiled wire the battery + and - were attached to, the number of seconds that current was run through the coil, how hot the coil became and anything else that would be needed to make one of these work?

This might also be a way to re-magnetize weak B1A ringers.


The picture should illustrate the direction of the magnetic field in relation to the polarity and the direction of winding. The original polarity could be easily determined using a compass. Keep in mind the south pole of the magnet will attract the "north" side of the needle. if in doubt, try with an iron nail or something else.
A car battery will easily flow 1000 amps or so and melt a thin wire in a hurry. In the video an old, defective battery was used. Not a bad idea it seems, as the possible current will be limited then.

WARNING: As a young guy I blew up a huge truck battery by arcing on the poles. No fun I can tell you. The acid spilled all over my clothes. Thankfully I was not hurt.


This is basically what I did and pretty much is the same as Countryman described.

1) the 4 bar magnets were so depleted that i could not determine polarity. I did the old string technique. Hung the magnet from a thread and waited for it to find magnetic north. It was inconclusive.

2)Based on #1, I just decided to re-magnetize all 4 the same way but to keep track of the finished N/S of each.

3) The solenoid was pretty simple, I use a length of 24awg twisted pair and made as many tightly wound coils as would fit, because this was a pair of wires I was actually doubling the number of turns.  I wrapped the magnet along the length in counter-clockwise turns.

4) I left a short length at either end, stripped them and twisted the ends together.

5) I connected the ends to a 12v car battery and literally touched it to the terminals for a second at a time, and repeated 3 or 4 times.  The side connected to the + terminal becomes N and the - is S, at least that is how I understood what I read during my research.

I unwound the wire and had rejuvinated magnets. I should say that they are not good as new, but good enough.

I totally agree about the danger of using the care battery.  In my first attempt I used a few 6v latern batteries in series, but that did not seem to have enough power. Using the car battery I only had to touch the terminals a few times momentarily (less than 1 second). The small gauge wire got hot VERY fast, and could easily melt if held in place too long.

I know my description is not very precise, but hopefully someone can find it useful!

Thanks countryman for putting me on the right track.


Quote from: countryman on March 10, 2023, 03:46:56 PM
this guy shows his DIY magnetizer for magneto ignitions on very old engines.

The guy didn't show the wiring diagram in his car magneto invention. This screen shot shows, I think, the coils wired in series.

One side of power supply to brown
brown to far left side coil
Black from left side coil to one side of the switch
Other side of switch to grey
Grey to right side coil
Yellow from right side coil to other side of power supply

Is the direction of current flow in each coil is important? That is, should the field of each coil be in the same direction or reversed?

Swapping black and brown and/or yellow and grey would reverse the fields, right?

I guess the question goes to one of the coils being N and the other S at the top ends, not both N or S.

This is great information that may help resolve the issues encountered with changing out coils in B1A and C4A ringers (where disassembly caused magnetic field loss).


Great thread JimNY.

Thanks for finding this info countryman, and for expanding teleplay.
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