Before wasting your time, have a look at how it works.
If you are still interested, let me explain what I did. There are many implementations of a useless machine, some of them are pure mechanical machines which I love, most of them use two switches, some of them use a 555 timer ... and God know how many others.
The Digispark is a development board based on an Attiny85 microcontroller (http://digistump.com/products/1) it is an Arduino like hardware and software implementation. It is cheap and easy to embed in your projects. I decided to use this board instead of the more popular 2 switches, mainly because you have full control of the servo movement; you can decide the speed and the direction at will.
- Digispark development board (any other Arduino will work as well using the regular servo library)
- DPDT switch, although I only use half of it
- 180 degrees servo, I’m using HiTech HS-422
- Lego structure, although any other will do
- 5v power supply
Step 1: Most useless lego tower. Part 2.
I don't have the Digispark part for Fritzing, I'll just list the connections.
Arduino Motor Color
---------- ------- --------------
5V 5V Red
Gnd Gnd Black
pin 3 Signal Yellow
Arduino Switch Color Connector
---------- --------- -------- --------------
pin 0 Signal red mid
pin 2 SW Gnd black any end connector
The digispark has only one pin for ground, if you need more than one you'll have to use a regular pin (2 in this case) and set it to 0 (ground) in the setup section.