Frankenstein light switch

Andrew Peleikis of Toronto made a video to show us how to install a "Frankenstein" knife switch to control the 12V lights he bought at Ikea.

So for a little home-improvement hacking this time, I installed a sweet knife switch to turn on/off the ikea lights i put up in my kitchen.

You can use a switch that has bare contacts like a knife switch as long as the power that is running through the circuit is SAFE - 12 volts or so - and even then, don't short the contacts with a fork or what have you, because it will still make a big spark and scare the children.

Link

• [weaponx]

  Dr. Frederick Frankenstein: For the experiment to be a success, all of the body parts must be enlarged.
  Inga: His veins, his feet, his hands, his organs vould all have to be increased in size.
  Dr. Frederick Frankenstein: Exactly.
  Inga: He vould have an enormous schwanzstucker.
  Dr. Frederick Frankenstein: That goes without saying.
  Inga: Voof.
  Igor: He’s going to be very popular.

• [Skep]

  I’ve always wanted to do this with a relay or some such but I’ve never found a source for giant Frankenstein style knife switches, though I suppose they wouldn’t be too hard to fab out of brass and wood…

• [BTPearcy]

  Uh… What a terrible idea. First of all, it isn’t Voltage that kills (when you zap yourself on the doorknob, thousands of volts of direct current are transferred between the knob and your finger…) Amperage kills, and depending on what amperage the circuit breaker or fuse protecting that circuit is, you could still be in for a nasty shock.

• [loftwyr]

  Won’t somebody please think of the children!

• [eliterrell]

  Yeah, that’s a great idea. I want to put in a switch like the RIGHT BY MY SINK so I can turn on the light while my hands are soaking wet. That would be brilliant. Assuming I can’t get one in my shower.

• [Skep]

  Come on guys, the execution may be off but the idea is very cool.

  The idea is to make it look dangerous and retro without actually being so. This could be done completely safely using a control voltage to a logic or relay circuit rather than passing the full current.

  Of course, I also thought it would be cool to use a new Erlenmeyer flask with a biohazard sticker on it for my orange juice (keeps people out of your stuff), but I eventually decided its bad to develop a practice of drinking out of labware–well, that and the juice always tasted like the rubber stopper :-) (If I can taste it I have to assume that the rubber is interacting with other people’s flask contents, so I wonder if that screws up any lab tests?)

• [z]

  Sigh, when I looked at the pictures on the site, it’s just a tiny knife switch. Damnit, we need bigger schwanzstuckers and knife switches!

• [Rob Cruickshank]

  Perfectly safe. The 12 volts on these lights is isolated from the mains via a transformer, and even with wet hands you’d not be likely to get more than a tingle. Note that many of the halogen lights sold have exposed conductors-that’s legal because it’s safe. Except maybe in Boston.

• [sinclair]

  @#3:
  “it isn’t Voltage that kills … Amperage kills”

  That argument has always bothered me. Your body is a Thevenin equivalent circuit. So is whatever you propose to electrocute yourself with. The current and voltage applied to your body are inextricably linked. It takes lots of volts to push lots of amps through you.

  The doorknob zap does put many amps through your finger. The saving grace there is the very short duration.

  The danger with this knife switch is not so much electrocution as it is burns. If the switch contacts become contaminated or oxidized then the whole assembly may become very hot. There’s a reason microswitches have largely replaced knife switches. They are much less prone to melting.

• [dculberson]

  Yeah, from experience, you can grab both leads of a 12v circuit, even a non-current-limited one, and not get a shock.

  It looks cool, it’s safe, and fun. Very cool!

• [BTPearcy]

  @#10:

  You can kill yourself with a 9 volt battery, if you set your mind to it:

  http://www.darwinawards.com/darwin/darwin1999-50.html

  @#9:
  You are 100% right about voltage and current being inextricably linked – it’s the law (Ohm’s law). But it is still current (which is measured in amps), not voltage, that kills you. Like the old electricity/water analogy – (volts = size of the pipe, current = amount of water flowing through it). No matter how small the pipe is, eventually enough water will flow through it to drown you.

• [dculberson]

  Okay, yes, but I did say “grab.” I will admit that if you get an open wound on both hands and then push both sides of the current source into your open wounds, and make sure they’re making good contact, you may cause v-fib and die.

  A standard brush with 12v terminals, including wet ones, will not cause those problems. Even if you did make solid electrical contact with just one hand, you’d be okay. It’s the cross-trunk current that causes .. problems.

  Hell, I brushed an energized 300v capacitor with my hand once. It caused nasty spasms but the excitement was limited to my left arm. I was taught early on to keep one hand behind your back if there’s any risk of high voltage contact.

• [JakeTheSnake]

  @#11

  I’m somewhat skeptical of the claim about the story of the sailor killing himself with the multimeter.

  http://msgboard.snopes.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=39;t=000945;p=1

  The language may shock you, or else you will be electrocuted with laughter.

  But the whole thing about current and voltage killing you, you still have to drive the current through you with something. If you’re going to argue by analogy, then I see voltage more like water pressure and current water flow, but this doesn’t even work perfectly. Electricity ain’t actually plumbing, so maybe it’s better understood through its terms.

  As an electrocution hazard that switch is about as dangerous as a 12V battery. But I agree with Sinclair about the other hazards from the knife switch.

• [whitcwa]

  The National Electric Code states that for low voltage (less than 30 V) lighting systems the components must be UL listed and the bare conductors shall not be less than 2.1 meters (7 feet) above the floor. It’s probably safe, but it isn’t to code.