These photos should show how you can hack your own hexbug to add an LED.
The basic idea was to add a simple feature so the HEXBUGS can play in the dark. Unfortunately the power supply for the hexbug is only 1.5 Volts which really gives you only about 1.3 Volts when the motor is running and the lowest forward voltage of any of the LEDs I have handy is 1.8 Volts. To produce the necessary voltage, I considered a few different solutions but the easiest to implement was just adding another 1.5 Volt battery in series for just the led.
2) Solder two wire wrap wires in parallel with the motor so that the switch turns off the led as well.
3) Using a small knife cut two notches so that the case fits back together cleanly.
4) Solder the wires to the extra battery to get 3 Volts and attach them to the LED. Check polarity. Use CA Glue to attach the surface mount LED to the front of the robot.
5) The battery can be taped on to the back and adjusted for balance. In the future I may try to find smaller batteries that can fit inside the hexbug or blink the LEDs with a storage capacitor.
Here is the video of it in action.
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