I've made several tattoo guns in the past and put a few tattoos all over my body with success however I wanted to make a nicer tattoo gun and go over one because my last gun was too fast and caused a bunch of scabs so some bits and pieces of the tat came off while it healed...
anyways I decided that I wanted to make a nice tat gun that has a variable speed and it's rotaty based but is based on an electro magnet...
I went to radioshack and bought an automotive relay to tear appart and take out the electro magnet.... To illustrate how this works, the electro magnet has a plate above it on a spring, so w hen there's no power going to the magnet(or negative power) the spring pulls the plate up but when you give it juice the magnet pulls the plate down...
anyways not to get into the details of the design... this isn't what this topic is about... but in a nutshell the plate is attached to a bar which goes through a shaft and at the end of the shaft is a piercing needle which comes out of a nozzle...
anyways so I was stuck with this delema: how do I make the needle to up a nd down.... I needed something that would work at about 12 volts, would rapidly turn on or off the electro magnet to make the needle move up and down....
I was originally gonna ask my brother to put together a circuit that does this cause he's an electrical engineer.... So I decided to give him a call. I asked him if he could think of an alternative....
he says: "Hey you make music, why not plug the tattoo gun into the power amp and play a sine wave?"
BRILLIANT!!!!
I unplugged my monitors and plugged in the tat gun powered up my emx, turned the volume of my amp up all the way and gave it an overdriven sine wave...
the result: a flawless working tattoo gun with variable speed...
what's really funny is that when you play the synth part keys the tatto gun actually produces different pitches. It's pretty funny.
Thought I'd share with my fellow electribers
peace.
... LOL !! 
