A project log for Bite-Sized Breadboards: Light Sensor

A short and fun interactive breadboard project. Cover the light sensor and the LED "eyes" light up!

Alpenglow IndustriesAlpenglow Industries 09/13/2020 at 00:400 Comments

Help, my circuit isn't working!  I know, it can be very frustrating.  Take a deep breath and start double-checking - there is always a reason and you CAN fix it!

If the eyes don't come on:

  1. Make sure the LEDs are pointing in the right direction.  It can be very hard to see which side is the flat side - make sure this is pointing "down", or toward row 2.
  2. Make sure the transistor is pointing in the right direction.  When looked at from above, it should look like a backwards "D".  The flat side of the "D" should be on the right.
  3. Make sure the battery is installed properly, + side up.
  4. If you're using a separate battery holder (not the blue adafruit board), make sure it's fully pushed into the breadboard.
  5. Make sure the switch is switched to the ON position.
  6. Make sure all components are in the right holes.
  7. Make sure all components are pushed all the way in.
  8. If you're outside or in a very bright room, it can be hard to block enough light with just your finger on the photocell.  Try going into a darker or shady space, or holding it against your body with your hands wrapped around it to keep light out.

If the eyes are always on:

  1. It's probably that you're in a dark space!  Try shining a light directly on the photocell, or try taking the circuit outside.  If the lights go off, you're set!  
  2. If the lights still stay on - go through the list above.

Help!  I bent a leg on a jumper or component and now can't get it into the hole.

  1. This happens!  First try straightening it out with your fingers.  Be gentle with the components (resistors, photocell, transistor), their legs are a little delicate and you should be able to straighten them easily.  For the orange jumeprs, be a little more forceful, you can try pinching your fingers together and pulling them down the length of the pin to straighten it.
  2. If that doesn't work, ask someone to borrow a pair of pliers!  This will definitely do the trick.