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Sunday, April 06, 2008

"Remote" turn-off switch

And now for something completely different: a hardware hack.

Warning! Don't attempt this at home unless you have at least some experience with electricity! Also, applying this hack directly on consumer electronics will most probably void the warranty!

The problem: having a 2.1 (yes, I know, lame, real people use at least 5.1 :-)) speaker system with an incredibly bright blue LED on the front and the turn-off switch on the back of the sub-woofer! The solution: installing a secondary switch to cut-off the power. What we need:

  • Tools
  • A switch rated for 220V (or 110V if you live on that part of the ocean) which is cable mountable. Usually these switches are rated for low amperage (ie what is the maximum power that they can cut-off safely), like small lamps, but the speaker system is also of quite low power consumption.
  • A piece of electrical wire. Again, use cable rated for the right amount of Watts. In the pictures you will see a cable composed out of 3 wires. Technically it would have been sufficient to use a 2-wire cable, however this was what I had handy.
  • An electrical plug
  • Isolating tape

The plan:

remote cutoff switch plan

The plan is to mount the switch on one of the wires, thus making it possible to turn on-off the speaker from a distance (a small distance, but at least you don't have to crawl on you knees to find the switch). In the version shown below the points A and B will be very close together (in fact they will both be in the plug). As I mentioned before, I had a three-wire cable handy, so there was one wire left unused, marked in the plan with a dash-dotted line.

Step 1. Cut off the original plug and clean the wires on a short distance (~5mm). I apologize for the poor quality of the pictures, but I had no "real" camera at hand.


Step 2. Take a piece of cable long enough for this purpose. Mount on one end the switch. To make it more "aesthetically pleasing" (and practical) you could mount the cable on one end. In this case I left the green-yellow wire unused (which is commonly used for grounding, so that it's easier to remember). A tip: at first cut off the outer isolation on a shorter part of the cable, mount the cable in the switch and finally cut off enough of the outer insulation that the switch can be mounted together again.


Step 3. Mount the other end of the cable together with the wire from the speaker in the plug. You should mount it the following way: one of the wires from the speaker goes directly to the current. The other one is fixed together with one of the wires from the cable (remember, I didn't use the green-yellow one, so that doesn't count). Finally the other wire from the cable is connected to the other contact. The contact between the the two intermediate wires should be thoroughly isolated.


Finally mount the plug together and use insulating tape to fix the remaining wires. You can now turn on-off the speaker (or anything else) from your chair without needing to crawl under you desk. You also being green, because the speakers (and other electrical equipments) draw power while idle and even while in standby!



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