2. Debugging

In the technology world, and especially in computer systems, we use the word 'debugging' to describe the process of finding errors and fixing them.

In case your LED didn't light up, we need to debug it and figure out what went wrong.

Power properly connected?
If we do not get any output (no LED light), first thing to check is if we have power, as in + to + and - to -.
LED properly connected?
As we mentioned before, LEDs have polarity, so we need to double-check that the positive lead (long leg) and the negative lead (short leg) are connected correctly.
Next up, if both the battery and the LED are OK, we are checking the resistor. If by mistake you used a different resistor, perhaps:
  • a much smaller resistor did not limit enough the flow of electricity and you burned your LED (when that happens, dispose it!)
  • a much larger resistor limited too much the flow of electricity so not enough power to light up the LED
The most common error in circuits that we build on breadboards are bad connections. As we said before, circuits are closed loops, so if one connection fails, we do not have a loop. You should also know that breadboards are used for temporary circuits and testing and of course are not 100% reliable. Apart from looking very carefully, the best way to check the connections, is by using a multimeter.