As someone who likes to take apart electronic things, I frequently pull stuff like LED's, motors, knobs, and switches out of old junk with plans to reuse them later. This instructable is not only an example of that reuse, but also the creation of a tool that allows me to test these parts quickly and easily.
By using a buck converter, I have a power supply that displays the voltage and can be adjusted, instead of always having to test parts using batteries and swapping out different battery combinations to achieve different voltages. Now that I have this power supply, I just clip the leads on and turn the knob! The Etch A Sketch is just fancy packaging.
Step 1: Materials
-an old Pocket Etch a Sketch
-a wall wart. (use the highest voltage you can find, this will be the highest voltage your power supply can reach)
-hot glue gun
-a sacrificial dremel bit
- 2 alligator clips
- an on/off switch
-a few inches of extra wire
-a sheet of plastic or other appropriate backing material
-rubber feet (optional)
-a patient girlfriend who trusts you enough to hold stuff while you solder it (optional but recommended)
Step 2: Cutting
The first step in the process is to separate the surprisingly fragile red plastic from the very sturdy black plastic. Use the cutting wheel on the Dremel to carefully cut into the black. Go shallow on the first pass, checking to make sure you haven't pierced the inner compartment where the powdered aluminum is. It will be insanely messy if you do, and you'll know immediately. Another reason to be careful during this part is because the red plastic is pretty fragile and you don't want to crack it. Just take it slow and easy. Do save that compartment of aluminum powder though, you can do some fun things with it! (Hint: Thermite)
Step 3: Mess Up Your Wall Wart
Snip the adaptor tip off your perfectly good wall wart and strip the positive and negative wires. Screw one of the wires into either the positive or negative inputs of the buck converter. Leave the other wire for now. This will connect to the power switch later on.
Here I used an adjustable wall wart, which is completely unnecessary since for this project you will want to leave it on the highest setting, as the knobs will be what allows you to adjust it. I suggest using the highest voltage you can find. This one just happened to be the only one I had that would allow higher than 9v.
Step 4: Modify the Potentiometer
The way you adjust the voltage on the buck converter is by using a screwdriver to turn the tiny screw on the potentiometer. Since I planned on using the Etch A Sketch knob, I needed to reposition the pot. Desolder the 3 pins and separate it from the main board. Then use the Dremel to file an old Dremel bit into a point that resembles a screwdriver. Make sure your point is able to fit inside your tiny potentiometer screw. Then use some hot glue to fasten this piece onto your knob. Pass the knob through the hole in the plastic and fit the pointy end into the slot in the screw. Use hot glue to hold everything in place. Then solder 3 long wires connecting the potentiometer back to the board. Alternatively, if you just happened to have a potentiometer that was the same diameter as an Etch A Sketch knob, and had a long enough rod on it, you could pass it right through the hole and fit it directly to the white knob. I was not that lucky.
Step 5: The On/Off Button
I used a button from a cheap dollar store lamp as the on/off button. By hot gluing the button into place inside the enclosure, I could attach the white knob to the outside. It took a little adjustment to make it fit exactly right, but after a few minutes I was able to click the button by pressing the Etch A Sketch knob. Solder one end of the button to the free wire you left on the wall wart. Solder the other end of the button to some wire and screw the other end to the only remaining power input connection of the buck converter. Your power button should now be fully functional!
Step 6: Running the Wires
Here you can see how all the wires are connected. The plastic was notched anywhere a wire needed to make its way out. The black wires coming in from the left are from the wall wart. One goes through the power switch so you can press the knob to turn the unit on and off then returns to the buck converter as a white wire. The voltage controls are the black, red, and blue wire twisted around each other. The black and red poking out to the right lead to the alligator clips, which have been stripped on one end.
Be sure to run your wires around the outside edges if you want a nice clean look. The tricky part is getting the buck converter to sit in the middle. You may need to adjust positioning of some wires or glue them in place.
Step 7: Get Feet!
I used some rubber feet from an old printer to give the buck converter enough height to press against the front plastic. Then I cut a scrap sheet of cardboard to fit the back opening of the red plastic. I covered the cardboard with shiny black plastic and put everything back together.
Step 8: It Works!
Test your completed unit and hopefully everything powers on! If not, check all your solder joints and wiring to make sure nothing's loose. Check out the video of mine working.
If you liked this, please vote for me in the Reuse and Before and After Contests! I'd also love to see your versions of this project so please share any if you have them. If you've got any suggestions for improvements I'd love to hear those too! Thanks for reading!