# A Reverse Dynamo - Opposite to the Shake Flashlight

## Main Question or Discussion Point

I would like to know if it's possible to build a dynamo that instead of having an electrical current driven through a coil by movement of a magnet to generate electricity could be driven by ac to move the magnet or coil in a vertical motion instead. If so, (which logically it sounds possible to me), could it be made small enough with low enough energy requirements and take up small enough space to be practical to drive a tattoo needle in a tattoo machine? I'll be the first to admit I'm a complete physics newb but I'm searching for a way to make a very low vibration generating tattoo machine to help prevent repetitive strain injuries caused by the vibration of the machine.
If I haven't searched the forum well enough, please feel free to tell me to get lost. :) I'm not looking for specifics but a nudge in the right direction(s) and theories to research would help me a lot.
Thanks.

Current magnetic tattoo guns operate very similar to a doorbell circuit
http://www.one-school.net/Malaysia/...ics/electromagnetism/images/electric-bell.png

I think this might be the right concept?
http://www.faqs.org/patents/imgfull/20110286868_01
But obviously with a completely different application and concept, I'm wondering if the physics required are the same and if it could be made small enough as I only need the length of my oscillation to be in the range of 1/16 of an inch to 3/16 of an inch.

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## Answers and Replies

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berkeman
Mentor
I would like to know if it's possible to build a dynamo that instead of having an electrical current driven through a coil by movement of a magnet to generate electricity could be driven by ac to move the magnet or coil in a vertical motion instead. If so, (which logically it sounds possible to me), could it be made small enough with low enough energy requirements and take up small enough space to be practical to drive a tattoo needle in a tattoo machine? I'll be the first to admit I'm a complete physics newb but I'm searching for a way to make a very low vibration generating tattoo machine to help prevent repetitive strain injuries caused by the vibration of the machine.
If I haven't searched the forum well enough, please feel free to tell me to get lost. :) I'm not looking for specifics but a nudge in the right direction(s) and theories to research would help me a lot.
Thanks.

Current magnetic tattoo guns operate very similar to a doorbell circuit
http://www.one-school.net/Malaysia/...ics/electromagnetism/images/electric-bell.png

I think this might be the right concept?
http://www.faqs.org/patents/imgfull/20110286868_01
But obviously with a completely different application and concept, I'm wondering if the physics required are the same and if it could be made small enough as I only need the length of my oscillation to be in the range of 1/16 of an inch to 3/16 of an inch.
Welcome to the PF.

Probably a better approach would be to make a counterbalance actuator that cancels out the motion of the tattoo gun. You would have a 2nd actuator that was on the same axis as the needle driver, but moving in the opposite direction to make the overall gun not move at all...

Without complicating the design of a tattoo fun further, could it be designed to tolerate a changed armature bar or spring tension (depending of the gun is going to be set up as a shader or a liner) or would it have to be exact? I would think it would have to be exact and it would also increase weight of the machine. Adding several ounces of weight to a tattoo gun would increase hand fatigue in long tattooing sessions as well as adding a significant amount of weight to shaders which need to be as light as reasonably possible and agile.
This is why I'm considering how to make my approach work rather than taking a different one.
Of course my assumptions could be entirely incorrect.

Oh and you're welcome :)