For the upcoming Nashville Mini Maker Faire, NashMicro is hosting a booth where they will be allowing participants to build “sonic screwdrivers”. The screwdrivers will be part of a joint exhibit between NashMicro and the LeanKit TARDIS. If you can’t be at the Faire, here’s how you can build your own sonic screwdriver at home using just a few cheap parts.
Prepare the Dowel
Saw a 1/8″ W x 5/8″ H slot in one end of the dowel to hold the battery. The easiest and safest way to do this is to drill a 1/2″ hole in a piece of scrap 2″x4″ to hold the dowel and then push this through a table saw.
Drill a 1/16″ hole at a 45 deg angle in both sides of the dowel. The holes should enter the slot near the middle of the height of the slot.
Insert the LED
Insert the leads of the LED into the two holes drilled into the sides of the dowel. Note which side you inserted the anode (+, long) side.
Insert the Battery
Slide the battery into the slot with the positive side facing the anode lead from the LED. Push it down and force the wires inside the slot to separate.
The LED should now begin flashing. If it doesn’t then try turning the battery around.
Some will notice that I did not use a resistor to limit current to the LED. The internal resistance of my flashing LEDs was sufficient with these batteries that they worked fine for over 3 days w/o any heat generated. You could probably extend the life to a couple weeks by soldering a 56 Ohm resistor to one of the leads.
Wrap the Battery in Tape
Add a couple wraps of electrical tape to hold everything together.
Add Your own Special Touches
A wooden dowel isn’t very attractive. Go crazy and add some paint, stickers, draw on it with markers. Make it your own!