Hack Your AC Adaptors To Power Low Voltage Electronics

Know that box of sad, unmarried, AC adaptors you’ve got lying around? Tim Matheson’s quickie video video tutorial shows you how to hack ‘em to power low voltage electronics.

This example shows converting a cellphone adaptor for use with a computer fan.

Be careful, electricity is dangerous. Franklin only able mastered it because he was a brain pimp. — BEN POPKEN

Hack your AC adapter [Tim Matheson]

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  1. I was surprised to find that most of the AC adapters I own have the same DC output, it’s just the plug that messes things up. It’s an interesting idea, but I’d be weary of leaving any of these “hot-wired” devices unattended for fear of overheating/fire.

  2. viriiman says:

    No so much of a hack. I’ve been doing this with case fans and the universal adjustable power adapters for a while (the ones you get where you can switch out the heads and the voltage).

    I thought it was going to be how to step the DC output up/down for a different device. At minimum, I thought there was going to be some wire stripping.

    Not bad as a starting point for someone looking to get into this, but I have to agree with crayonshinobi.

    One (last) thing he fails to address in the video is that you have to match the DC output or you can fry the device you’re wiring. A case fan will accept 1.5v DC to 12v DC and still run, but you can seriously fry something by giving it 9v DC when it only wants 3v DC

    (IANAE)

  3. were_only_gonna_die says:

    viriiman: stepping the voltage down isn’t too difficult if you got a few resistors and have soldered something before. cut the wire and add a voltage divider (http://hyperphysics.phy-astr.gsu.edu/hbase/electric/voldiv.html) between the adapter and connector. however, stepping the voltage up would require some active circuitry; it would be more time and cost effective to just buy a different DC power supply.

  4. sporesdeezeez says:

    I guess there’s no hard and fast rule for what makes a hack, but like viriiman I am not impressed. This is very basic…and if electricity is pretty much a mysterious and magical force to you, than you’re probably better off starting out with batteries.

    A roommate and I did something like this once back in college. He had an antique radio cabinet where the radio was busted but the speakers were still some solid 6x9s. I had an old MP3-CD car stereo laying around, so we rigged a sturdy 12V power supply (with suitable amperage) to it and then connected the speakers to the head unit. We mounted the head unit in a concealed location, and also kept power to the old radio so it would still light up. Nothing like listening to “I’m Sorry Miss Jackson” on what appears to be a shortwave radio.

  5. He had his power in the hole and now he can feel a nice cool breeze there.

    Couldnt resist taking his comments out of context.

    As a response to the ‘this is a little too basic’ comments, I thought that his commentary included some very good habits that a beginner could learn from that you might not find in a more advanced tutorial that assumes you already have formed those good habits.

    It is not too much of a stretch to see somebody leaving things plugged in or powered on while working on them. Or to see another person test the power without checking the work area before going live. Like some of you said, it is a very basic tutorial however, Tim Matheson exemplified some very good practices when working with electricity.

  6. Tim Matheson says:

    I will admit I am somewhat a novice when it comes to electronics. I would have broke out the resistors and my multimeter to get the correct voltage and amperage but the sd card was filling up faster than I could talk. I first seen someone do this with a homemade tattoo gun and thought what a great idea opposed to stripping the adapter and rendering it useless for its intended use. In regards to “stepping the voltage up would require some active circuitry” would you just have to add a capacitor and resistor to the positive feed? Like I said I am new to electronics.

  7. we're only gonna die says:

    tim: a capacitor won’t do any good for a DC circuit. DC is at a frequency of f = zero Hz and the impedance of a capacitor is 1/(i*2*pi*f*C) where C is the capaticance, f is the frequency and i is the square root of -1. so, at f = 0, the impedance is infinite. the real part of the impedance is the resistance, so you have infinite resistance. long story short, a capacitor at DC simply looks like an open circuit (infinite resistance).

    to increase the voltage on a DC circuit you need some active circuitry. if i remember right there are some DC/DC converter ICs that will step up a DC voltage but they require additional circuitry and are not very efficient. if you’re interested take a look on http://www.digikey.com

  8. robdew says:

    How can we stem this trend of huge “instruction” video files (especially out of focus ones) where one picture and a couple of sentences would have been sufficient?

  9. wikkit says:

    The problem with DIY DC adapters is, as someone else pointed out, getting the right male connection for the device. I thought about hacking a high-efficiency computer power-supply to power all of my rechargeable electronics. This would give me energy efficiency + less clutter = me happier. But the aggravation of finding the right connectors is too much for me.