Here is the Smoke Tester. It’s a board designed to safely power prototypes for the first time and see if there are shorts. Current can be measured using a voltmeter. Here’s the full feature list.

  • 5V and 3.3v voltage regulators
  • 7V-15V input
  • 3 possible input sources: USB, 2mm DC barrel jack, and screw terminals
  • 3 possible outputs: USB, Banana Jacks, and screw terminals
  • Polyfuses with fuse blown LED indicators on both rails
  • Current to voltage converters – aloes you to read the current simply with a voltmeter
  • Jumpers to bypass the current measurement shunts
  • Jumper to bypass the 5V voltage regulator, allowing you to power the 5V output rail directly from the USB input

Design files are available in our SVN.

This design is intended as a workshop tool, but if enough people like it might go into production as well. The current measurement feature was inspired by Schazamp’s “USB Power Supply with Resettable PTC“, we strongly suggest you check it out.

Prototype boards will go out soon with any updates. If you have any suggestions please leave a comments below, or check out the forum thread about it.

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  1. I think this is a great idea. I think this is in many ways more useful than the ATX breakout. Everyone has wall warts around to power it. However, that said, I think 15V max is a little limiting in that I think that people have 5v wall warts and 16-20v laptop supplies. These days 9v wall warts are a little less common, although easily purchased. I know it is a trade off, If you are going to go for 30v max, you likely want to have a switch mode buck to avoid too much heat dissipation…… So it’s a trade off. How about adding a panel meter so you don’t have to tie up a multimeter on current output. Seed can probably source some really cheap ones rather than making your own.

  2. What about some pick off points and a couple blank pads for the usb data lines for those doing iphone/ipod charging circuits.

  3. Looks like a winner to me, I’d certainly buy one. No complaints about the input voltage – I’d probably use batteries anyway.

  4. Hi Ian! How are you?

    Cool board.

    I just noticed something. I think, the connections of the Drain and Source pins of the p-mosfet LED drivers are swapped.

    Also, I second the panel meter idea.

  5. Looks like the cheapest useful digital panel meter (10 V max, resolving 10 mV) is about $8 on ebay. The cheaper ones are 30V or 99V range and only resolve 100 mV.
    But for under $5 you can get a 3.5 digit multimeter including 200 mV range with 1 mV resolution.

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