Servo - September 2009

Tune in each month for a heads-up on where to get all of your “robotics resources” for the best prices!

Simple Brains —

Going Back to the Basics

Microcontrollers like the BASIC STAMP, BasicX, Arduino, AVR, PIC, and all the others make short work of just about any robotics task. So, it may seem daft to even consider designing and building a robot with “old-fashioned” retro electronics — you know, circuits designed around the 555 timer IC, or (heaven forbid!) a rag-tag collection of op-amps, flip-flops, and shift registers, or (perish the thought!) all discrete components using only transistors, resistors, and capacitors.

Such circuits take longer to build, and in some cases, are more expensive than a microcontroller

chip that can provide the same functionality. So, why even think about doing it? For an education in electronics, of course!

The circuit diagram of the typical microcontroller-based robot is laughably simple: power input with a voltage regulator (if that), maybe a couple of bypass and filtering capacitors, a few other odds and ends, and that’s it. Microcontrollers are more about the software that operates them, rather than the electronic components that hang off them. As a result, hobbyists and students who have been exposed only to microcontrollers tend to have

an incomplete understanding of electronics — theory and practice.

A small desktop robot powered by a basic analog or digital brain is a good way to teach yourself the basics of electronics. Circuits are reasonably inexpensive to build, and if you use solderless breadboards (recommended) you can make quick and easy improvements. With these points in mind, let’s take a look at going back to robot basics with simple brains — botronics sans microcontroller.

Finding Suitable Circuit Designs

Ramsey Electronics offers a wide variety of hobby kits for learning about and experimenting with electronics.

When I came of electronics building age, the transistor was fairly new and exciting (some of my first kits were tube-based, even!). Now, hardly any new circuit design for robots uses a transistor; unless it’s a power transistor for operating a motor. Most newly published circuit designs will — by preference of the author and realities of the marketplace — use a microcontroller.

So, you have to go into the archives to find the good non-microcontroller circuits. Fortunately, thanks to the Internet, CD-ROM publishing, and something called the public library, locating good circuit designs to serve as robot brains isn’t hard to do.