Carpet Monster by Joseph Birr-Pixton

An experiment in walking, falling and gaits. 

Well, it just walks forward!! So far a few emergent behaviors
have been seen, such as making it's way around obstacles and
scaring my cats!!

- Powered by 9V PP3 battery, via 7805 regulator.
- Two semi-hacked RC servos providing torque to legs.
- An NE555N timer chip and a 4017B logic chip providing motor
  firing pattern.
- Motors directly driven by two piggy-backed 74HCT245 driver chips.
- About 5 or 10cm per second, very much variable with surface.
- Legs and chassis made with two coat hangers; soldered with
  standard 40/60 solder at joints.

Parts used:
        The Electronics and Motors: 
1 * NE555N timer IC. 
1 * 4017 CMOS Logic 1 of 10 counter IC. 
2 * 74HCT245 octal tri-state driver IC. 
1 * 7805 voltage regulator (5V). 
2 * 3K3 0.25W 5% resistor. 
1 * 47uF (micro farad) 25V Electrolytic Capacitor. 
1 * 100nF (nano-farad) Ceramic Plate Capacitor. 
2 * Radio Controlled servos OR 50 rpm gear boxed motors. 
1 * PP3 9V battery with clip. 
        The Chassis: 
Two all metal coat hangers. 
5 * 200mm cable ties. 
4 * pair of M3 machine screws and nuts.  

Problems Encountered:
- The legs fall off if it falls off a surface.
- The leg stoppers kept on falling off. This was fixed by
  soldering a cross brace behind each of them. You can see
  this in the far front leg in the picture.
- The rubber end caps to provide grip just aren't grippy
  enough. This could be remedied with flat feet or softer
  rubber feet.

Time to build:
Three hours in total

10 or about $15

Website URL:

Includes a guide to making your very own carpet monster!


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