You want to give people electric shocks when they touch your circuit? Adds new meaning to “hands-on” electronics.
A taser can be hacked from a disposable flash camera—or so I’ve read on the internet (sorry I have no links to post). What does a photo flash have in common with a taser? They both slowly charge a capacitor to a high voltage—even from a wimpy battery—then quickly discharge all that electrical energy into the target—a xenon flash tube (in the case of the camera) or a human being (in the case of a taser). On a bigger scale that’s also how they power rail guns, I think.
I’m familiar with a battery-powered medical device called a peripheral nerve stimulator (PNS). There are several kinds of medical pulse generators. A PNS generates electrical pulses up to a few hundred volts in amplitude, for a duration of a few microseconds (millionths of a second) to cause a mild muscle twich. A single pulse may be uncomfortable but tolerable, while a rapid train of pulses (at maybe 50 or 100 Hz) induces a painful tetanic muscle contraction.
Tasers (same as “stun guns”?) work much the same, I believe, but at much higher voltages of a few hundred thousand volts, i.e., a thousand times what a PNS delivers. Also I believe a taser directly stimulates skeletal muscles into contraction rather than indirectly via motor nerves as with PNS. You can see how it might stop attackers in their tracks.
I suppose you could hack a disposable camera into a harmless shocking device by dumping most of the pulse’s energy into a dummy load (no relation to your potential victims) like a low-value resistor or RLC network, in series or parallel depending on your circuit—set up so when somebody bridges the electrodes with some part of their body, they get only a mild shock. Meanwhile the dummy load never complains.
In fact there are amusement park arcade games that deliver increasing levels of (presumably harmless) electric shocks to your hand when you grip a metal fixture—the object being to see “how much you can take.” Don’t know if they’re still around. Perhaps you could research how they work—pulses or steady voltages? What’s the specified maximum voltage, current, or pulse duration that the game’s manufacturer is willing to assume product liability for? Keeping in mind that exceeding the specs might cause a bunch of dead customers…
(I’m old enough to remember “hot chassis” radios & TVs in the days of two-prong non-polarized plugs. You had a 50–50 chance of plugging in the appliance so its metal case could deliver a fatal shock when touched.)
In any case I’d be very safety-conscious about shocking people—possibly you—with any home-brew device that creates high voltages (high enough to feel) generated from a low-voltage battery.
If you like to fool around with electrical circuits try making 5-volt or 3-volt circuits (those are standard chip voltages) to light an LED, make an audio click, signal your computer or whatever. Even if the circuit is wrong, you are safe. Two good topics for beginners: (a) digital logic chips; (b) 555 timer chips. Also check out micro-controllers like Arduino or Propeller. Plenty of free online resources, plus Nuts and Volts magazine.
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