Is it possible to build a low-voltage Thompson right jump apparatus?

Thread Starter

CrayV

Joined Feb 23, 2023
1
Hi all, I'm attempting to build a jumping ring apparatus (a core of iron with the bottom wrapped with wiring like an electromagnet, so that when a metal ring is placed on top of the coil and a current is run through the coil, the ring jumps up into the air). Looking on the internet, I'm seeing a lot of high voltage versions of the apparatus, though I am limited to 12V. Does anyone know if it's possible to build this with a limit of 12V?

Any and all help is greatly appreciated.

The apparatus I'm describing can be seen here:
 

MrChips

Joined Oct 2, 2009
31,057
The eddy current induced in the ring is a function of the current and frequency in the coil.
I have never done this experiment but it would appear that you need about 600VAC.
 

WBahn

Joined Mar 31, 2012
30,286
It depends on how much jump you want. The cryogenics demonstration kits typically have a small coil that is powered by a 9 V battery and that is used to make a penny or dime jump. At room temperature the coin barely moves, maybe a quarter inch. But then the coil and coin are cooled to liquid nitrogen temperature and now the coin jumps a couple feet.
 

MrAl

Joined Jun 17, 2014
11,683
Hi all, I'm attempting to build a jumping ring apparatus (a core of iron with the bottom wrapped with wiring like an electromagnet, so that when a metal ring is placed on top of the coil and a current is run through the coil, the ring jumps up into the air). Looking on the internet, I'm seeing a lot of high voltage versions of the apparatus, though I am limited to 12V. Does anyone know if it's possible to build this with a limit of 12V?

Any and all help is greatly appreciated.

The apparatus I'm describing can be seen here:
Hi,

These things look similar to the projectile launch apparatuses made by some people that throw things by the use of a strong, fast rising magnetic field.
I am guessing that the reason they use high voltage is to overcome the resistance of the coil so they can get a fast rising current through the inductance of the coil which then causes a fast rising magnetic field which then means a quick launch. They often have a bank of large capacitors that hold a significant charge at a high voltage and then using an SCR or something to switch on the coil the energy suddenly releases into the coil causing a fast rising magnetic field and the object launches into the air.

I think in theory you might be able to do it with 12v alone, but you would need very heavy wire and not too many turns or your current would not be able to rise fast enough. There is also skin effect which can limit the effective quick rise of current with large diameter wire so 12v may just be impractical. You should be able to get some jump, but not as much as with a higher voltage and thinner wire and many more turns.
To get a higher voltage from 12v you would use a well designed boost circuit that boosts the voltage up much higher to charge some capacitors, then when ready to launch you switch the coil on.

I guess you may have looked into some of the designs of these launcher things and that may help with your project.
 
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