Solar Powered Wireless Detector by Mark Dixon

Step 4 The Hack

On this example you can see that the manufacturer has kindly given us a circuit board showing the polarity of the output led. Positive is marked with a +. Unscrew or detach the retaining screw and inspect the way that the LED is fitted. In this case the LED needed to be de-soldered from the board. If there is no polarity marking on your example, you should be able to find a small flat on one side of the LED body, indicating the negative or cathode side. It is useful to take a quick reference snap with a camera or mobile phone so that if a any wires from the batteries to the solar-cell become detached, you have a record of where to solder them back on. I have found as a general rule taking snaps of products as part of any hack process forms a useful tool for future reference anyway.