Give your Hexbug a Real Brain!
Chapter 2 - What's Inside -
As observed earlier, the Hexbug has just three functions when turned on- Forward, Reverse turn upon bumping its antennae, and Reverse turn after a loud sound. ( There is no Pause, or Stop ) The microphone and the antennae on the PC board are easily observable, but what’s inside? If you gently try to move the legs, you find that the right legs are locked, but the left set can be moved. These are also the legs that stops moving when the bug makes its reverse-right turn. This indicates that some sort of a clutch must be driving this side. Opening the battery compartment reveals two L1142 batteries. These are alkaline batteries rated at 1.5v, 105mahr at a drain of .25ma., and indicate that the system runs at 3 volts and under. (Typically, the useful life of a standard alkaline battery is considered over when its voltage drops to .9 volts. After this, the voltage drops rapidly- .8 volts is the “gooey-ooze” stage. This means the system can run on a supply voltage as low as 1.8 volts.) A single screw near the antennae can be seen through the transparent shell. It is the only one, and holds the PC board to the chassis, and the front of the two halves together. At the back of the bug body, there is a small rectangular cut out with a tab in it. This holds the back halves of the chassis together.
But to learn more, we need to open the bug up...
The first step in opening the Bug, is to remove the transparent plastic shell. It is connected to the chassis by seven press fit pins. They can be freed, one at a time, by wedging an X-Acto knife or other sharp, thin edge into the crack between the chassis and shell posts. A little wiggling should pop each free. Removing the small screw near the antennae will allow the chassis to be opened. Do this carefully if you want to look inside- You do NOT want to dump out all the small gears and clutch parts!
Gear train, motor, clutch, battery and battery contacts
If you can curb your curiosity, and be satisfied with the pictures, don’t open it. Strap the two halves together with a piece of wire that held the Bug in its package.
Inside of Spiral-ramp clutch
There are four electrical connections between the chassis and the PC board. Two stiff battery contact wires pass through the chassis from the battery compartment and provide power to the PC board. These must be unsoldered first, using either a solder-sucker or de-soldering braid. (To prevent accidentally shorting the batteries during unsoldering, take them out, and insulate the top contact from the battery with a small piece of paper, Not plastic- the heat of unsoldering could melt it. Re-install the batteries. This will make re-assembly easier by preventing the contact wires from shifting/falling out after they are unsoldered.)
The last two connections are the red and blue flexible wires from the motor. These are more easily removed after the PC board is removed.
With the two halves of the chassis strapped together, remove the small screw, and gently pry/wiggle the board off the central post. Apply the soldering iron to the motor wire connections on the top side and lift the board as the chassis pulls away. Repeat this for the other wire, and then replace the screw to hold things together. (And so the screw doesn’t get lost!)
Next, the antennae need to be salvaged. The antennae are very well designed. They are actually two pieces- the outer spring wire, and a partially insulated center post. Unsolder the spring wire first using either the solder-sucker or de-soldering braid, and then the post. Note that there is a right and left antenna. This will be important when re-assembling them on a new circuit board.
Now we have a robot bug chassis ready for a new brain!
1]The micro-robotic Hexbug is the result of collaboration between Ignition (Plano, TX; www.ignition.com), an industrial design and development firm, and Innovation First Inc. (Greenville, TX; www.innovationfirst.com), a product engineering company. RadioShack is the exclusive North American retailer of the Hexbug. Bandai, the leading toy manufacturer in Japan, also recently signed a deal for global distribution rights, with plans for other products to follow. “We had a rough idea for this product, but Ignition brought it to life,” says Joel Carter, VP of marketing at Innovation First. “They transformed our concept into a viable market-ready product and helped us to create an entirely new product category.”