Curso De Electronica

PROJECTS: MOUSEBOT

MOUSEY THE JUNKBOT
www.makezine.com/02/mousebot

By Gareth Branwyn

With a few spare parts, you can turn an old computer mouse into an amusing little robot. >>

Set up: p.99 Make it: p.100 Use it: p.109
Photography by Kirk von Rohr 96
Make: Volume 02

THE FINE ART OF MAKING “FRANKENMICE”
This project turns an analog computer mouse into a robot that’ll delightfriends and wow workmates down on the cube farm. Mousey’s behavior is fittingly mouselike. It scoots quickly across the floor, thanks to lively little motors. And when the critter crashes into anything, it speeds off in the opposite direction. The robot’s “brains” are an ingenious hack based on an audio operational amplifier (op-amp), an 8-pin chip that’s normally used to drive answering machinespeakers and other lo-fi equipment. Following Randy Sargent’s pioneering design (see page 102), Mousey repurposes this chip to boost light-sensor input to motor-powerable levels. The result is simple, fast-reacting analog circuitry that fits inside a mouse case.
Gareth Branwyn writes about the intersection of technology and culture for Wired and other publications, and is a member of MAKE's AdvisoryBoard. He is also "Cyborg-in-Chief" of Streettech.com.

Make:

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PROJECTS: MOUSEBOT

www.makezine.com/02/mousebot

INSIDE MOUSEY

How a mild-mannered computer mouse becomes a fast, freewheeling photon-hog.
Analog (non-optical) mice pick up movements of the ball with two axles that turn gear-like wheels. The teeth rotate between IR emitters and receptors that capture the flickeringshadows to read horizontal and vertical directions and speeds. Reverse-biasing the diode emitters turns them into Mousey’s “eyes.”

Mousey’s bumper (from one of its buttons) empties a capacitor-full of current across a relay, temporarily crossing the motors’ voltages and throwing Mousey into reverse.

Randy Sargent’s Herbie (below) was the first LM386-based bot. It finished last in the 1996Robothon’s line-following race, but went on to spawn many descendent designs.

The eyes’ light difference is amplified and tapped into the circuit between the two motors, wired in series. As one motor draws less power, the other uses more, steering the bot.

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Make: Volume 02

Illustration by Timmy Kucynda

SET UP.

Visit makezine.com/02/mousebot for source list.
J H C E N L K B F AM D O

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First, you’ll need an analog (non-optical) mouse to cannibalize for its case and several parts inside. If you don’t have an old mouse or two gathering dust, ask friends and colleagues. Otherwise, you can buy a new, super-cheap model such as the Kensington ValueMouse, which costs $10 and has enough space to fit all of your components inside. The bigger and more symmetricalthe mouse, the easier the build will be. “Handed” mice with asymmetrical, curved bodies present problems.
MATERIALS: Mouse case [A] 2 Light sensors From mouse SPST touch switch From mouse Double-pole, double-throw (DPDT) 5-volt relay [B] From analog modem, or Solarbotics #RE1 LM386 audio operational amplifier (op-amp) [C] From answering machine, speakerphone, intercom, etc., or Solarbotics #LM3862 Small 4.5 VDC motors [D] From motorized toys, or Solarbotics #RM1A / Mabuchi FF-030-PN 2N3904 or PN2222 NPN-type transistor [F] Solarbotics #TR3904/ TR2222 Light-emitting diode (LED) [G] 2 Spools of 22 to 24-gauge stranded hook-up wire [H] Ideally, 1 black and 1 red 4 Pieces of 22-gauge, solid-core hook-up wire [I] Ideally, 2 red and 2 black, 6½" long 9V battery [J] 9V battery snap [K] 1k to20k resistor [L] SPST toggle switch [E] Solarbotics #SWT2

The other components can be scavenged, or purchased from an electronics retailer. For the motors and other specialty parts, we recommend Dave Hrynkiw’s Solarbotics (solarbotics.com) as an excellent source. Where available, we’ve listed Solarbotics parts numbers for components, and they now offer a complete mousey kit for about $20...