Hi, this is Wayne again with a topic “Weekend Projects – Vampire Flashlight”.
Hi I’m Sam Freeman, with make the Joule thief circuit is very popular project in the maker community. It can take a high brightness LED that would normally require three volts or greater and turn it on with only a single double a battery and a handful of components. Plus it can do this for the double-a, that’s so drained. Most people would call it bed yep. This little flashlight is a voltage vampire. This is a moderately difficult build, but it should only take a few hours to complete check out the project page for detailed, build instructions and a lot more information on how it works. We’Ll give you a clue: it’s not science fiction.
You will need the following parts to build this project, many of which can be picked up at your local RadioShack and others. You may already have in your stash of components. You’Ll also need these very basic tools for assembling the circuit, we’re going to be soldering directly to the battery cases built-in terminals. These are mounted and relatively thin plastic that can easily melt which will result in killing the battery pack to be safe, we’ll remove them from the case to tin the terminals once the tend clip the wires and carefully reinstall them.
In the case, next we’ll install the momentary, switch or button that will activate the light tin. One of the leads on the switch next strip, one end of the black wire and solder it to the lead. Diagonally opposite thread: the black wire through the holes. In the case and fit the button in place touch the tip of your soldering iron to the switch lead at the battery negative terminal just long enough to make the connection and then immediately remove the iron. Next, we’ll grab a length of clear and colored magnetic wire and twist the ends together now we’ll wind, the wires around the toroid ten times make sure the coils are evenly spaced and that the wires do not cross each other. When you’re done, one pair of wires should protrude from the top of the coil and one from the bottom next clamp one side of the wires and seal the whole assembly with a few coats of nail varnish well want to run current in opposite directions around the Toroid so untwist the wire pairs and swap the colored wires from each side, then twist the new pairs together to make sure they don’t get mismatched.
It’S a good idea to test the circuit on a breadboard to verify that it’s working prior to soldering. If the circuit is dead head on over to the project page for some troubleshooting tips and tricks to build the final circuit begin by wrapping the leg of the 1 kilo, ohm resistor around a scrap of wire to form a small loop. Next bend the middle leg of the NPN transistor 90 degrees up from the flat side of its body and solder, its resistance other leg. Next secure the pair with some heat, shrink, tubing and cut off the excess leads leaving just the loop attached, but the flat side of the transistor against the backside of the LED as shown and wrap the outer transistor legs around the LED pins on each side and Solder them in place, then snip the excess leads from the LED and transistor legs.
Next, we’ll trim and sand off the enamel on the wires protruding from the toroid twist. One sides wires together and then solder them slip. These soldered wires into the center of the positive terminal on the battery case and carefully solder them to the terminal, then trim the excess wire on the other side of the toroid slide. Some heat shrink tubing over the remaining colored wire Sanvi enamel off of the end and solder it to the resistor loop slide, the tubing up over the solder joint and apply some heat to shrink.
It run the black wire from the battery case through the negative side of the LED assembly and the bare copper wire through the positive side of it, pull the wires out to cinch the LED assembly tight against the toroid once everything’s in place strip and sound the Wires and solder them to the assembly trim the excess wires, install the battery and you’re done. Although this was a bit of a tricky soldering project you’ll be happy with the results. It’S not only a good demonstration of the clever Joule thief circuit, but it’s also a very good use for all those dead batteries and it’s the perfect little flashlight for finding your way around. Whenever the lights go out, you .