INTRODUCTION
Here is a very unique little kit that’s great for kids. The WEB1 is a little robot made completely out of electronic parts and wire. It’s pretty easy to build, and once it’s adjusted properly, it will entertain for hours. It has little pager motors in it that vibrate and propel it on its little wire feet. How fast it goes is adjustable by bending its feet and also by a pot that controls motor speed. When it approaches an obstacle such as a wall, it turns to avoid it. It does this with a second little pager motor.
WEB1 CIRCUIT DESCRIPTION
This is a fairly simple circuit, and easy to follow even for a beginning kit builder. The kit uses a 555 timer U1 to pulse the two pager motors. The 555 timer does not directly drive the motors, but instead turns them on through transistors Q1 and Q3. This is done because although the motors don’t draw much current on average, they do when they initially start spinning. The 555 objects to these big current spikes, so the transistors take the beating instead. Normally only one motor is running and the WEB1 moves in a straight line. In this state, U1 is pulsing Q3 which drives the motor attached to pad P1. This motor’s speed is adjustable via R2. When the WEB1 gets close to an obstacle, infrared light emitted from D1 bounces off the object and into the infrared phototransistor Q2. Then Q2 switches on and turns on transistor Q1 which drives the motor attached to pad P4. This motor causes the WEB1 to turn aside from the obstacle. The sensitivity of phototransistor Q2 is adjustable through R5. Without this adjustment, sometimes room lights would turn Q2 on and make the WEB1 turn all the time. Okay, let’s get building.
WEB1• 4
