Published on: February 09, 2009
See this page http://web.media.mit.edu/~silver/drawdio/play.htm
I decided to build that pencil. I collected documents from Ladyada’s Drawdio page. The TLC 551 IC was not available in the electronics market in THRISSUR. Actually TLC 551 is a low voltage version of LM 555. So I decided to replace TLC 551 with LM 555.
After building the circuit, I fed it with 5V supply. Since it was LM 555 I fed 5V. If it were TLC 551 we can use a AAA battery to power the circuit.
But the transistor started to heat up. I think that the transistor (amplifier) circuit was designed to be powered from AAA battery. So the 5V might have made it to heat up.
There comes my hack. It’s not actually a hack. I found that we can easily replace the amplifier circuit and the speaker with a buzzer. I have redrawn the circuit with the buzzer. You can download the modified circuit.
This circuit succeeded for a 5V powered LM 555 circuit. But I don’t think it will work if you use a AAA battery to power the circuit and also replacing the LM 555 with TLC 551. If the circuit is powered by a AAA battery, the buzzer wont produce sound that is much audible. so in that case you will have to use the amplifier and the speaker circuit.
These are the two snapshots that has been modified from
Use this snaps together with the circuit diagram to build the DRAWDIO. See these snaps. These are test run done by me on the breadboard.