I like to have as many tools as close as I can right at my fingertips. In a previous instructable I showed how you can put a small air compressor right on your desktop. In this instructable I'm having a little fun and creating my own continuity tester within easy reach. I decided to have it respond with a tone as well as an LED. That's when I got the idea of making it into a Darth Vader continuity tester.
Step 1: Command Station
I utilize a centralized station in my work area I half/heartedly call my command station. It connects to two ATX power supplies so I have varying voltages from +3V to +24V with -12V and -5 volts as well as a variable supply for voltage. It has a built in voltmeter and amperage meter so all I have to do is pull the leads out and measure instead of wondering where my portable one was at that moment. However, while working with this setup, I realized I needed a continuity tester. I was always having to still find my multimeter, switch the leads to measure continuity then use it and put it back.
Step 2: Mold
The first thing I did was take an old candy holder shaped like Darth Vader's head. It comes apart into two pieces which works wonderfully in order to vacuum form.
Step 3: Vacuum formed shell
I vacuum formed a shell out of a 0.40 styrene sheet. It turned out pretty good by my standards (which are usually pretty low but this turned out better than expected). I cut out the Vader shell then cut out the eyes.
Step 4: Paint
Next come the black glossy spray paint.
Step 5: LEDs
I then took a styrene strip and cut it the length of the Vader shell. I measured where the eyes line up and cut two holes. I used two red LEDs with 220ohm resistors soldered in series.
Step 6: Lining up the eyes
I then glued it to styrene to the Vader shell. I made sure to solder about 6" of 22 gauge wire to each lead so I had some room to work with it and not run short.
Step 7: Attaching to primary board
I drilled a hole into my primary board to run the wires through. I tested the LEDs by connecting them to the 5V wires inside. The eyes looked perfect. I proceeded to use some black screws to attach the shell to the outside of my primary board.
Step 8: Noise
Next I needed to make sure I got a sound whenever I got continuity. So I used a Piezo buzzer. I wired one side of the buzzer to the Vader shell then a permanent +5V in series with the negative connection going out to be the second lead. So I end up with one continuity lead connecting to the buzzer and one connecting to the negative of my ATX power supply.
Step 9: Easy access tester
This type of continuity tester runs a little less than 3V through whatever circuit your testing. I'm planning on building and replacing the strict series circuit with a 555 timer tester, but haven't built it yet. Anyway, I like the way Vader's eyes light up whenever I complete a circuit. It's cool and worth the build just for that. It's also now very easy to pull the leads and test a circuit whenever I need to without having to find my portable and reconnect the leads to measure continuity. What can I say. . . I'm a little lazy when I'm at my work desk and like the easy way sometimes.