Page 196 - Robot Builder's Bonanza

SPECIALTY TOYS FOR ROBOT HACKING 165

Figure 16-4 You can combine LEGO
pieces with homemade plastic parts for
such things as making mounts for radio
control servo motors.

beam to a bracket for a servo motor (see Figure 16-4), and use it as a mounting bracket for a
cardboard- based prototype.

Specialty Toys for Robot Hacking

Some toys and kits are just made for hardware hacking (retrofitting, remodeling) into robots.
Some are already robots, but you may design them to be controlled manually instead of inter-
facing to control electronics. Here are just a couple of ways you can use inexpensive toys to
make homebrew robots.

TAMIYA
Tamiya is a manufacturer of a wide range of radio- controlled models. They also sell a good
selection of gearboxes in kit form that you can use for your robot creations. One of the most
useful for starter bots is the Twin Motor Gearbox (item number 70097), which consists of two
small motors and independent drive trains. You can connect the long output shafts to wheels,
legs, or tracks. This gearbox is used for the My First Robot lessons; refer to Appendix A,
“RBB Online Support.”

One big disadvantage of the Twin Motor Gearbox is that the DC motors it uses are quite
inefficient. Under heavy load or stall (powered but stopped) conditions, the motors can draw
G over 2 amps each. That’s a lot for this size motor. (Amps and other terms are covered in more
detail in Chapter 22, “Using DC Motors.”
The Twin Motor Gearbox is acceptable when controlled by switch or relay, but when using
transistor control you should replace the DC motors it uses with more efficient versions. Pololu
and several other online retailers offer these replacements; cost is under $3 per motor.

Other Tamiya kits include single motors with selectable gear ratios, basic walking and roll-
ing robots, wheels, and more.

OWIKIT AND MOVITS
The OWIKIT and MOVITS robots are precision- made miniature robots in kit form. A variety
of models are available, including manual (switch) and microprocessor- based versions. The
robots can be used as is, or they can be modified for use with your own electronic systems.
For example, the OWIKIT Robot Arm Trainer (model OWI- 007) is normally operated by
pressing switches on a wired control pad. With just a bit of work, you can connect the wires

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