If you want to make your own Drawdio without doing any soldering, read on…
This post will describe how to make a Drawdio like the one I made.
What you’ll need
- Screw terminal block (2 rows x 8 ways)
- BC549 transistor
- BC559 transistor
- 2.2nF capacitors (2-off)
- 10k resistor (brown, black, orange)
- Piezo sounder (not a buzzer!)
- 2AA battery holder
- AA batteries (2-off)
- pencil (HB’s don’t work very well, 2Bs or 4Bs are better)
- small amount of kitchen foil
- drawing pin
- some wire
- screwdriver for the terminal block
- wire cutters/strippers. You can get away with scissors if you’re careful :)
Start off cutting your terminal block to 2 rows of 8 screws. Bend the legs of your transistors like this and screw them into the bottom row of your terminal block. The BC558 goes on the left with the flat side uppermost. The BC548 goes on the right with the rounded side uppermost:
On the top row:
- The red wire from the battery holder goes to the left-most screw (number 1)
- The black wire from the battery holder goes to the right-most screw (number 6)
- 10k resistor between the 3rd and 4th screws
- the piezo sounder also goes between 3 and 4
- 2n2 capacitor between 2 and 4
- 2n2 capacitor between 3 and 5 It’s a bit of a fiddle getting more than one wire in the screw holes, but persevere – it’s doable!
Finally, to prepare the pencil – take two lengths of wire. One length goes from screw 5, the other end you need to wrap around a drawing pin and push into the pencil at the top. The other length you need to strip a longer length of insulation off (about 5 cm), wrap around the pencil where you hold it, and then cover it with aluminium foil to make a good contact for your hand. The other end of this piece of wire goes to screw 2.
Right, it’s done – put the batteries in, hold them pencil and touch the lead to your other hand. You should be rewarded with a squeaky noise :) Draw a blob on the paper, stick your finger on it and then draw lines radiating out from it. Get someone else to hold hands and then they can do the drawing. The possibilities are endless – have fun!