I always wanted to make a Jar Light to use it in our garden in summertime. Since white LEDs with high luminosity are available realizing that simple LED Light is very attractive.
To keep it simple I built the circuit on a breadboard. All the parts of the Jar Light are assembled with duct tape. Realizing the project takes about 20 minutes.
1. The circuit
The quite simple circuit is made with 2 white 18000mcd LEDs. As power source I use three rechargeable NiMH batteries with a capacity of 800mAh providing 3x1,2 = 3,6V.
In a further project the batteries might be recharged with a distinct Solar charger.
Considering the technical data of the LED and the possible voltages using rechargeable batteries, the design of the circuit is a compromise between high light output, low power dissipation and long lasting battery power. That´s why I used two LEDs, each with an 68 Ohm Resistor connected to 3,6V providing 2,9V and 10,33mA to each LED. The overall power dissipation is about 14,5mW. 800mAh batteries will last about 30 hours.
So let´s have a look at the stuff we need.
1 Mini breadboard (170 tie points and a peel and stick adhesive backing)
1 Mason Jar (diameter according to the dimensions of the mini breadboard)
1 Battery holder for three AAA batteries
1 Mercury tilt switch
2 Resistors 68 Ohm
2 LED 5mm white 18000mcd
1 piece of double sided duct tape
1 piece of wire (0,6mm diameter single solid core wire)
Step 1: Build the Circuit
1. Try to put the two LEDs in the centre of the breadboard to have them in the middle of the lid.
2. Put the two resistors between the tilt switch and the anode (long lead) of each LED.
Note that the tilt switch has to be orientated upside down to switch off the LEDs when the Jar stands upside down.
3. Connect the cathode of each LED to the negative pole of the battery.
4. Use a piece of wire to link the two cathodes.
5. Finally connect the battery to the breadboard.
Now put the batteries in the holder an test your circuit. To switch on the LEDs, turn the breadboard upside down.
Step 2: Assembling
1. Cut a piece of double sided duct tape and stick it on the downside of the battery holder.
2. Stick the breadboard on the cover of the battery holder.
3. Stick the battery holder on the lid of the Jar.
4. Put the lid on the Jar and let your new light glow !