Author: dave-o

I grew up in the suburbs of Detroit, where it was common for adolescent boys to rig up ways to electrocute each other using the guts of old camera flashes or BBQ lighters. (Don’t ask; before I wrote SNIP, BURN, SOLDER, SHRED, I though this was a totally normal thing everyone did growing up. Having written the book and done lots of events and talked to lots of folks since, I’ve learned that this was a totally weird pass-time that, like Pączki Day and Devil’s Night Arson, was almost entirely limited to the Detroit Metro Area.) The Ticklebox (Project #7 in SNIP, BURN) is one such homebrew shocker.
click image to embiggen the schemo



If you’re having trouble getting your Ticklebox to properly shockify your friends and family, work through this troubleshooting checklist:

1. How’s your battery? If the tilt switch is working (you can check it with a multimeter, or by just rigging a AA battery and an LED through it and seeing if it turns on and off when tilted) but the relay isn’t clacking, check your battery. A good, fresh 9V is needed both to trigger the relay and to get a good shock out of the capacitor.
2. Is the relay wired properly? It’s *super easy* to bung that up the first time, especially if you’re new to hobby electronics.
3. Is it a bum relay? Radio Shack relays seem to have occasionally spotty quality assurance. My design calls for a 12V relay, which is higher than you need, but which regularly works fine when driven by a 9V. That said, I’ve seen folks complain that the Shack’s 7-9V relays wouldn’t click over until they’d exceeded 9.5V or more.
4. This is more of a footnote than a troubleshooting tip, but here goes: For reasons I can’t fully fathom, I used a Radio Shack relay rated for 12VDC, instead of the proper 7-9VDC-rated relay. I’ve now started to wonder if using the 12VDC relay has a performance outcome: The tech reader for SNIP, BURN had trouble building his Ticklebox using a 9V-rated relay (it worked, but gave a weak jolt). At that time we chocked this up to the fact that he was using really junky enclosureless relays he’d gotten surplus god-knows-where, and there was a lot of grit on the contacts. When he rebuilt using a Radio Shack #275-248 relay (like the one in the book) it was a dandy shocker. Meanwhile, my demo shockbox (same design, using that wonky 12V relay) has been taking abuse at events and fairs for two years, and still shocks children as good as it did on day one.
5. Are you “pulsing” the switch? This project sorta hinges on making a DC supply yield an AC-like current; folks get the best shocks from my demo boxes when they jiggle. The goal is to stutter the switch so it makes a series of “*clacks!*”.
6. Are you a leathery old dude? I’ve found that some folks don’t shock well (this often correlates with age: Pretty much any little kid gets a shock, but some adults don’t, esp. old men). I’ve puzzled over this, and think it may have to do with skin resistivity (this is because the perceived jolt–which is based on the current applied to the skin–is a function of the speed with which the capacitor drains; faster drain means a bigger bite. Check out the *WARNING!* and footnote on page 300 for details). So, the question is: Have you tested this on a youthful volunteer yet? You might be less shockable (which might come in handy some day).
7. Did you use the right capacitor? I generally keep the caps in my hobby projects at 16V or 35V. I’ve heard of folks having trouble with caps rated at 50V (although I haven’t personally had these problems). I can’t think of an occasion where going higher in V has made a project malfunction, but I *have* had issues using higher rated capacitors (i.e., 1000uF or more) in other shock-and-spark projects; these sorts of projects need the cap to drain quickly to give a jolt, and larger uF caps seem to drain slower.

BONUS: KipKay did a lil video on this project a while back:

CLARIFICATION: Kip has used a magnetic reed switch in place of the tilt switch, but hasn’t really made clear that in order for the reed switch to function like a tilt switch you need to add a magnet to the mix so that, when folks rattle the box, the switch closes-&-opens and they get zapped. An easy way to do this is to get a length of plastic soda straw and a small magnet. Trim the straw to about 3 inches long, drop the magnet inside, and seal up the ends so that the magnet can freely slide back and forth. Tape this assembly to the side of the reed switch; when you tip it back and forth, the magnet should slide past the switch, causing it to briefly engage. *Zzzzzap!*

My NTE Cross Reference Chart
NTE makes replacement semiconductor components; for anything that Texas Instruments or National Semiconductor or anyone else has produced, NTE has a workalike. But, these workalikes’ names are usually *totally unrelated* to the canonical name for that IC. For example, the 555 timer IC popularized by Signetics in the 1970s–which pretty much everyone else calls a SOMETHING-SOMETHING-555 (for example, Fairchild Semiconductor calls these “NE555″s, and Exar calls them, you guess it, “XR-555″s)–NTE calls these “NTE955M”s. Similarly, the ubiquitous “LM386” op-amp used in my (and everyone else’s) Dirty-Cheap Amps ? NTE calls that a “NTE823” (obviously).
If you buy NTE components–which work great–make a point of noting the “normal” name for whatever you bought and keeping that with the IC. If you go around buying garage sale or eBay lots of electronic components (which is a *great* way to cheaply juice up your project supplies, with the added benefit of often including surprisingly cool, handy, or valuable parts), you’re going to end up with a bunch of cryptic NTE stuff sooner or later. A chart like this will help you sort those out–and likely uncover some great lil gems.
My NTE Cross Reference Chart