Tricking skill testers and other machines into giving free credits

Using a piezoelectric "shocker", it is possible to trick certain coin receptors into "thinking" you have inserted a coin, when all you've really done is create a voltage spike in the electronics that was misinterpreted as the signal for "this guy has inserted a real, valid, authentic coin".

I have tried this with some success on coin slot modern machines, including vending machines, children's rides, parking gates, arcade games, and skilltesters. Here's a demonstration on a skilltester (crane game):

Skilltesters have preset payout rates, so really there's no skill involved. The claw's strength is set randomly, and in this demonstration the machine had a 2% payout rate, meaning that 1 in 50 games would be capable of lifting up the prize and dropping it in the chute.

How does this work? Can I do it?!

Yes, and it's pretty simple. If you're like me, you probably already know of these zappers by pulling apart electric lighters to see how they work! ...after which you proceeded to torment all your friends with it by zapping any piece of metal that they happen to touch.

This "zapper" is a piezoelectric igniter, it works by striking a piezoelectric material (such as quartz) with a springloaded hammer which generates a high-voltage potential difference between the terminals you can see in this picture:

For the purposes of this article, the black wire is terminal 1 and the brass endcap is terminal 2.
The black "stick" protruding from the other end is the striker.

When the striker is pressed, it will compress a spring-loaded hammer which will then release and strike the piezoelectric material generating a potential difference spike between the terminals causing a high voltage spark to jump up to a centimetre between the terminals and ignite a any flammable gas that happens to be there.

Implementation

So in the video above, you can see that I just modified the lighter by taking out the gas internals leaving the zapper in there with its trigger. What you probably didn't notice, is the grounding wire I've incorporated into the handle. This wire leads from terminal two to the handle where it's exposed simply so that when hold the device, the wire is touching me, grounding terminal two. You need to do this, otherwise no potential difference will be created between terminal one and the thing you're zapping (the zappee), and no spark will occur. By the way, the terminals are interchangeable -- it doesn't matter which one you use for what.

So in summary, you need to touch one terminal to ground it, and zap the machine with the other terminal.

Action

So once you have your zapper, you need to find something to zap. Remember, it makes a difference where you zap, and while you're aiming your jolt of electricity at the coin circuit, that jolt of electricity can take a roundabout route to said circuit. I found a vending machine where I had to zap a screw on the other side of the machine to get a dollar, and when I zapped closer to the coin slot the machine just reset.

Warning! Please note:

While it's highly unlikely and I have not encountered any situations where this has permanently damaged a machine, it is possible. Also, please note that cheating these machines and/or even just zapping them intentionally is probably illegal, so be aware of the legalities before doing anything.