Bathroom joule thief night light

thingiverse

This is a night light for when you stay in a hotel and get up in the middle of the night to find the bathroom pitch black! Turn on this light as you go to bed, place it in the bathroom, and adjust the brightness accordingly. Then, when you visit the bathroom at night, the light provides just enough illumination to see by without needing to turn on the main light and blind yourself. As this is a 'Joule Thief' circuit, the LED will burn for seven days straight with a new battery, so it should last for 14 nights. Parts list: Ferrite core small - (try to get as many turns on as possible) 2 meters of thin enamelled copper wire - (around 0.25mm) Single AA battery holder On/Off flashlight switch 20K potentiometer, (Linear) Potentiometer Knob - (or print a suitable one) Any NPN transistor - typical 2N222A 10mm red LED, (diffused works best) 1000 Ohm resistor Small length of wire 4 small screws To wrap the coil, fold the copper wire in half and thread it through the ferrite core, two cores at a time. This ensures that the coil is wrapped correctly. For instructions, refer to: https://www.youtube.com/watch?v=K53beWYdIpc Assembly: 1. Solder the transistor to the legs of the LED with Collector to +ve and Emitter to -ve. 2. Glue the LED/Transistor into housing 3. Fit the potentiometer. 4. Glue the Flashlight switch into housing 5. Fit the battery holder. 6. Trim wires to suit. 7. Solder the battery wires to the switch and -ve side of the LED. 8. Solder the common coil wires to the other side of the switch. 9. Solder one coil wire to +ve side of the LED 10. Solder the other coil wire to 1000Ohm Resistor 11. Solder the other end of 1000 Ohm Resistor to central connection on potentiometer. 12. Solder the wire between potentiometer and Base of transistor. 13. Test, if all OK, secure components with a bit of hot glue or epoxy. 14. Fit lid. Tip: Use blue tac to hold your components when soldering.