Functions:
Basically it just goes forward until its whiskers detect a collision. If the left whisker is activated, then the right wheel reverses for about 0.5 seconds thus turning the robot away from the obstacle and then it continues straight forwards (this also happens with the right whisker/left wheel).

Specifications:
- Powered by 4*'C'cells, via 7805 regulator.
- Two hacked RC servos providing torque to wheels.
- Two NE555N timer chips in monostable mode triggered by the microswitches on the whiskers.
- Motors directly driven by two piggy-backed 74HCT245 driver chips.
- About 15 or 20cm per second.
- All circuits built on stripboard.

Parts used:
The Electronics and Motors:
2 * NE555N timer IC.
2 * 74HCT245 octal tri-state driver IC.
1 * 7805 voltage regulator (5V).
4 * 6k8 0.25W 5% resistor.
2 * 47uF (micro farad) 25V Electrolytic Capacitor.
1 * Dual gang 100k Linear Pot.
1 * 100nF (nano-farad) Ceramic Plate Capacitor.
2 * 'Hacked' Radio Controlled servos.
1 * PP3 9V battery with clip.

The Chassis:
2 * composite sheets
many * 200mm cable ties.
many * pair of M3 machine screws and nuts.

Problems Encountered:
- Can *theoretically* get stuck when approaching a flat object perpendicularly (head on). This does not tend to happen in real life because of the fact that it very rarely approaches *absolutely* head on.
- Whiskers cannot detect objects below and above their line of height.
- *Really* poor name(!)

Plans for Extension:
- Phototropism (+ve and -ve; you can actually see the LDR's in the photo)

Email: jbp@cheerful.com