Horseshoe Rickenbacker recharge

[StarryNight]

Anyone successfully regauss a 60s Ricky horseshoe? Wondering what the right method is for charging with neodymium. Do the sides of the U get charged or the ends? Any tips would be appreciated!

[soundmasterg]

Go to this website. I recall a thread there probably from 8-10 years ago in the bass section about recharging those. Might be some info in the pickup section too.

Greg

http://www.rickresource.com/forum/

[StarryNight]

Thanks! I did go check a few threads out. Most of those guys are not too familiar with pickup construction. Some have removed the shoes and charged them against speaker magnets with varying degrees of success. Some have tried to charge the shoes while the pickup is still attached to the bass. I looked at the patent for the pickup and it seems one polarity is shared across the topside and the opposite is on the bottom. I guess I’ll have to disassemble the pickup to get access to the bottom of the shoe.

[Helmholtz]

You may try the method described here http://dennysguitars.homestead.com/P...iceRig1P1.html

Better results can be expected using a strong electromagnetic charger. In this case the horseshoe is placed on top of the poleshoes of the charger so that it forms a "bridge" for the magnetic flux.


The 2 U-shaped magnets have their poles at the small ends (like typical horseshoe magnets) and are mounted north-to-north (upper side in the patent drawing) and south-to-south, i.e.in a repelling arrangement.
Problem is that close like poles mutually demagnetize.

[StarryNight]

Brilliant, thank you. That confirms how the magnets are orientated.

[J M Fahey]

Considering the 30s when those pickups were originally designed, agree with horseshoe magnets being magnetized "along the U path" so one flat face North, the other one South.

Way back then it was *common* recharging Alnico U shaped magnets, because of their universal use in car engines, tractors, etc. so a "magneto recharger" was not unusual by any means.

Gingery published an excellent book on how to home build one (paradoxically nowadays they are not common since ignition systems changed); here are some pictures:

the-real-thing






In case it´s not clear, coils create strong North and South poles at the massive square endplates and U magnet is used to "bridge" them, providing an easy path for magnetic flux and getting charged in the process.

Maybe you can clone the magnetic circuit using Neo magnets and some pieces of iron?

[StarryNight]

I hadn't really had a need to build an electric magnet charger but this could be a fun project. Looking at these pictures it seems like you've got two beefy coils around some beefy steel, likely wound opposite of each other, being fed some amount of juice. I assume a current limiter needs to be involved. Where's an EE around here when you need one! :-)

[ric]

I hadn't really had a need to build an electric magnet charger but this could be a fun project. Looking at these pictures it seems like you've got two beefy coils around some beefy steel, likely wound opposite of each other, being fed some amount of juice. I assume a current limiter needs to be involved. Where's an EE around here when you need one! :-)

You were just talking to one. (Juan)
;-)

[StarryNight]

You were just talking to one. (Juan)
;-)

I'm sorry, I should have mentioned I suffer from chronic foot-in-mouth disease.

[Lollar Jason]

I have worked on hundreds of those and analysed the material. They are hardened by heat treating and are not tempered. The shoes will warp somewhat when heat treated so many of the sets dont line up on top where they meet. People will try to bend one of the shoes to make them line up and they snap the magnet at the U. Never try to bend the shoes!
The only other thing worth mentioning is on rare occasion youll find a shoe that wont charge up- something is wrong with how it was hardened or they slipped in the wrong material but even plain steel will magnetise for a short period although not very effectively. This happened to mccartneys bass according to Arnquist. I have seen two or three shoes that wouldnt charge in the last 25 years so its hardly worth worrying over but it can happen. Normally youll get around 200 to 300 gauss at the end of the shoe- when they only read 16 or 20 gauss and wont go any higher thats what you find. If you measured at the inside or outside of the bend youll get nothing- they are strongest at each end and the field rapidly declines as you go toward the bend. Thats why the stock 8 string pickups have lower volume on the two outside strings- DOH!

[StarryNight]

man, talk about a temperamental pickup! Jason, it must have been a real challenge to recreate these. I also hear the originals had the coil wire wrapped right around the screws, so adjusting the screw height means instead death for the coil? Not sure if that's true or not (and not willing to find out).
thanks for the gauss readings. that will help with getting a baseline (oh, very punny!)

[J M Fahey]

I hadn't really had a need to build an electric magnet charger but this could be a fun project. Looking at these pictures it seems like you've got two beefy coils around some beefy steel, likely wound opposite of each other, being fed some amount of juice. I assume a current limiter needs to be involved. Where's an EE around here when you need one! :-)

Currently unavailable but some pop up now and then at Amazon and others:
https://gingerybookstore.com/MagnetoMagnetizer.html

Not really needing a dedicated current limiter, wire resistance does that.

[Lollar Jason]

I had a gingery magnetizer and a bull dozer battery but it was a pain in the butt to make and keep it trickle charged- it worked though! Now I have one of those commercial units about $400- works great. One side of the steel pole shoes are made to charge horseshoe magnets . This photo shows one with the poles arranged to charge horseshoes- the horseshoe sits on top not inbetween the two charger poles https://www.neomagmagnets.co.in/self...magnetizer.htm

[Helmholtz]

(Re-) magnetizing a horseshoe magnet requires a stronger magnetizer than a straight magnet of the same material. The reason is that the horseshoe cannot be placed directly between the pole-shoes. The magnetic flux thus has 2 options: taking the shorter direct path through the air-gap between the poles or the longer path through the horseshoe. The percentage of flux that runs through the horseshoe depends on its length and its permeability (magnetic conductivity). Alnico typically has a relative permeability of around 4. That means that it conducts magnetic flux 4 times better than air. But if the path through the horseshoe is longer than 4 times the air-gap, the major part of the flux will choose the air-gap and not be available for magnetizing.

The earlier steel magnets (e.g. Co-steel) are easier to magnetize than alnico, as their permeability is higher (e.g. 12) and the field required for saturation is lower.

Always maximize the direct between-the-pole-shoes air-gap (still allowing for good support/contact of the magnet) when magnetizing horse-shoes.