This is a very simple little tool that I've nonetheless found incredibly useful for breadboard prototyping! It's a little stick with two pins, spaced the standard 0.1"/2.54mm, marked + and -, with LEDs in opposite polarities. When current flows from + to -, the green LED lights up. When it flows the other way, the red LED lights up. Nifty!
Handy for all kinds of quick-and-dirty testing! I use these to double-check that I've hooked up the power rails on our breadboards correctly, as indicators for microcontroller projects (no need to worry about adding a resistor!), to test reverse voltage protection circuits, and more.
It can take up to around 12V in either direction (but will light up with as low as 3.3V).
Now also available in a double-sided version!
Nov. 23, 2013, 4:41 a.m.
Why two resistors? isn't one enough. Such waste :)
Nov. 23, 2013, 5:54 a.m.
I don't think it's possible to create this functionality with two LEDs and one resistor, although I'd be thrilled to learn that I'm wrong!
Oct. 13, 2013, 7:52 p.m.
Not a question, but a suggestion: It would be fantastic if you combined this with the breadstick to make a polarity-indicating breadboard power bus jumper. It would be like a breadstick with sauce... maybe you could call it marinara? Price it around $3.00, and I think they'd sell like [food reference removed].
Oct. 13, 2013, 8:38 p.m.
Aug. 19, 2013, 3:02 a.m.
Will this die after long-term use with a battery providing 14V or so?
Aug. 19, 2013, 4:41 a.m.
Probably-- it would exceed the power rating of the resistors.
I bought the polarity stick, and I like it. I previously burned out a LCD by mixing up power and ground wires in wiring up my breadboard power rails. This stick will hopefully prevent this in the future.
Two minor improvements come to mind, if the creator ever plans for a new version:
1) I find when I'm attaching stuff to the breadboard, that the height of the stick gets in the way. It would be nice if a separate version were offered that had right angle pins so the board doesn't stick up, but lies flat.
2) If it doesn't add too much to the cost, having the +/- on the reverse side of the pcb would come in handy at times when I have the board reversed. It would be even more useful if the board had two sets of LEDs on each side of the PCB, so that I don't have to turn the board around to see the lights.
Oct. 15, 2013
Oct. 15, 2013
This may not be the worlds greatest tool, but if it stops you from accidentally releasing the magic blue smoke or spending hours tracking down a wiring issue late at night, it has more than paid for itself in my book. I probably should have ordered more than one.
Sept. 22, 2013
Many uses, checking polarities, power indicator, breadboard blinky LED indicator. It's more convenient than discrete LED and resistor. By far. Glad I got this on a whim. I'm always using LEDs. No more digging around for resistors. No more wondering if I have power. Nicely done. Only problem? I only bought one. :)
Aug. 6, 2013