Syringe Logic Probe

[Travis] sent in his oh so simple(why didn’t I think of that) syringe logic probe. that he put together for his version of the sump logic analyzer. Real probes tend to be pretty expensive. With some effort, you can probably fit an led/diode/resistor in there and make a simple 5v logic probe. If you’d like a nice logic analyzer, Spartan-3 board that it’s based on is only $99.

14 thoughts on “Syringe Logic Probe

  1. i’m torn between making a joke about downloading a virus like hepatitis from reusing the logic probe and making a joke about being able to use heroin while hacking

  2. For you kids out there, this is an old idea and was pretty common back in the day that logic probes were a more common piece of test equipment. I remember seeing it in an electronics magazine nearly 30 years ago.

  3. if I was more awake I’d make a joke about track marks/PCB tracks.

    Actually, my concern is with the needle being stainless steel, which isn’t a very good conductor. I wonder if there are any alloys that will “stick” to stainless but enhance its conductivity ? A better idea might be to get that ultra-tiny kynar wire, and run it *inside* the needle, and have a tiny exposed lead coming out, maybe coat the stainless neeedle with a non-conductive film.

    If kynar wire didn’t work, just unwrap some braided wire and use one braid, although that may conduct with the steel tube and mess up the signal. I would highly advise putting it back in a box when you’re done, if you forget and drop that in your toolbox or on your floor, Murphy will assure you find it in the most painful way possible.

  4. @dan:
    Buried? Where do you think you are?

    Dan: A household pin doesn’t have the precision of a needle. In some cases, when working w/DIP stuff, you can just use a paper clip. This is good for when you are working on a very small scale circuit.

  5. Pretty neat. I wonder if you could make an array of these things with variable spacing for a logic analyser.

    Polymorph this might actually work well for extracting data from broken PCB’s you might run into, and reflashing “dead” PC motherboards.

    Now, the really clever bit would be to incorporate a talking frequency/waveform analyser into said syringe :)


  6. Can anyone tell me how I could use a logic probe to test laptop motherboards? I would like to use a logic probe to test mosfets, voltage regulators and controllers like maxim/isl chipsets.

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