Tygosar Mousey The Junkbot! Install the LM control chip. It scoots very quickly across the floor, thanks to lively little DC motors. It uses a small integrated slide switch to control a high-side power MOSFET that can deliver continuous currents up to around 16 A at 4. Figure motor and battery placement.

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Determine if the mouse has enough space inside. Screws may be hiding under little nylon feet or tape strips on the bottom. Step 2: Perform a mouse autopsy. Next Prev Remove all of the mechanics and electronics from inside the mouse. Unhook the mouse cable from its plug-type connector, pop out the scroll wheel if it has one , and pry out the PCB.

Use a Dremel or other rotary tool with a cut-off wheel or grinding head to remove everything from the inside of the mouse case except the screw post that attaches the bottom of the case to the top.

Plastic dust is nasty stuff, so work on newspaper and wear safety goggles and a dust mask. Step 3: Add the power switch. Next Prev The last piece of prep work is adding the power switch, a large toggle placed rear topside so it looks like a tail. Find an appropriate mousey-tail location, then drill a hole in the case big enough for the switch.

If the switch has a threaded bushing and two nuts, take one nut off, insert the bushing through the hole, and then tighten the nut back down onto the outside of the case. In some cases, a plastic screw post interferes with the tail. If so, cut out the post and reconnect the top and bottom halves with tape or glue. If you want to create a more critter-like look for your Mousey, you can add a length of plastic tubing or other material over the toggle to create a tail.

Step 4: Figure motor and battery placement. Next Prev Figure the arrangement of the bigger components and cut openings for the motors. Mouse shapes vary, so use your judgment here. The two motors should be perpendicular to the centerline of the body. Leave enough space behind the motors for the battery. The shaft angles coming from the body should support the bot and set the proper speed. Step 5: Installing the bump switch and adding tires.

Look on the mouse PCB for a tiny plastic box that clicks when you press it down. Desolder it. Tape a long strip of hard plastic in place, so that it covers the tiny switch button and runs along the front of the mouse like a wide bumper.

When you press the plastic, you should hear an itty-bitty click. Now you can add some tires to your motor drive shafts. Find a rubber band with the same width as the sprockets on the drive shafts if your motors have sprockets on them. Cut to length, wrap, and glue the rubber band onto the shaft.

You can make the wheels thicker by continuing to wrap the band. Rubber or plastic tubing make good tires, too, as does corrugated tubing from a Lego Mindstorms kit. If one signal is lower than the other, the chip boosts that signal to equalize the one output.

In our case, the inputs are light values rather than audio. If we hook this output to two DC motors, we have a little brain that reads input from two light sensors, compares them, and boosts the power on the dimmer side.

This creates a robot that follows a light source, auto-correcting itself as it moves. This makes Mousey scuttle away from light after any collision, adding to its lifelike behavior. The mouse works either way, this arrangement just improves sensitivity of the IR sensors. The breadboard images Steps DO NOT yet reflect this fix, so make sure to follow the circuit diagram when installing these two parts. These emitters can work as both transmitters and receivers.

On most mice, the emitters are clear plastic boxes with a tiny dome protruding from one face, while the photodetectors are solid black. We want the clear emitters. Find the clear emitters and desolder them from the PCB. You are now the proud owner of a pair of robot eyeballs! Step 8: Give Mousey eyestalks. Next Prev Our IR emitters only have two stubby little pins on them.

We need to determine which pin is positive and which is negative. When connected correctly, you should get a reading of about 1V, with the red probe indicating the anode or positive pin. If you have red and black, cut two of each color. Solid core is better than stranded in this case, because it makes stiffer stalks. When the wires are soldered in place, twist them together and strip some of the jacket off of the other ends.

Step 9: Install the op-amp chip and main control circuit. Install the LM chip across the trench on your breadboard. With all ICs, pins are numbered counter-clockwise around, starting at the little dimple. Connect tie-points for Pins 1 and 8 together with a piece of hook-up wire. Connect the red wires together by plugging them into a node about five or six rows left of the chip. Translate accordingly for different breadboard layouts. Plug the negative lead of an LED the shorter end into the node with the two red eyestalk wires, and the positive lead into a new node on the opposite side of the trench.

Step Next Prev To create the runaway circuit, we need the bump switch you already pulled, a 5V DPDT relay, a transistor, and a simple timer made of a capacitor and resistor. When the capacitor has discharged, the transistor switches motor control back to the light-following circuit.

The resistance and capacitance determine the rate and amount of current discharged. You can play with different values until you find the runaway behavior you want. Try resistors in the 1k- to 20k-ohm range, and cap in the to microfarad range. The higher the value, the longer the discharge time.

We used a 10k-ohm resistor and a microfarad capacitor, which gave about 8 seconds of fast backing up. Plug in the relay about six nodes to the right of the LM, or although the relay actually has only eight pins.

Cross a wire from Pin 8 to Pin 11 and another from Pin 6 to Pin 9. These wires will reverse the motor connections when the relay is engaged.

On electrolytic caps, the cathode is usually marked with a stripe. Step Next Prev Plug in one end of the higher-ohm resistor to connect with the capacitor anode, and jump the other end over the trench to a new node on the other side.

Plug one hook-up wire into the bottom resistor and capacitor node, somewhere between the two, and a second wire up to the positive power bus. Bend the tips of the wires so they can touch, but keep them separated. These wires will act as the bump switch when you touch them together.

Connect Pin 9 to the negative bus. This connects the relay and transistor to power. Next Prev Now that we have a light-hungry robot brain, we need to install it in our mouse body so that it can feed cue Night of the Living Dead sound effects.

Before soldering, test fit the parts, starting with the battery, motors, and bump switch. Position the other components around these. As you arrange, check that the case still closes. That way, you can replace it when Mousey gets that run-down feeling. Make sure all of your wires are as short as possible throughout the build and keep making sure the top fits! Step Install the relay. This will connect to Pin 4 of the IC and power negative ground. Solder a 2" black negative wire onto the bottom-left pin Pin 9 on BB , and then a 3" red wire onto the bottom-right Pin 8 on BB.

Affix the relay into the case, in dead bug mode. Allow it to dry if gluing before soldering anything else. Step Connect the bump switch components. Next Prev With the relay close to the front, we can chain together the timer resistor, capacitor, and bump switch without needing additional wires. Using your multimeter on the 3-pin bump switch, determine which side pin connects with the middle pin when you click it, and clip off the other unneeded pin. Solder a 2" red lead to the middle switch pin, then glue the switch into the the body, through the hole you cut earlier.

Step Power the motors. Step Install the LM control chip. Next Prev Bend Pins 1 and 8 of the op-amp chip down and solder them together. Find the black wires from the transistor, relay, and capacitor, strip the ends, and solder them all together side-by-side. Solder a 1" black wire to Pin 4 of the op-amp, and the other end to the negative wire junction. Solder the red wire from the relay to Pin 6 of the chip. Then glue the chip into the mouse case in dead bug mode.

Next Prev The buttons on most computer mice are separate, semi-attached pieces of plastic. On the inside, trim the two red wires so that they just overlap against the underside of the lid. Solder them together. Connect the booster by soldering the free end of the resistor to the middle pole of the toggle power switch and the LED cathode to the junction of the two red eyestalk wires.



Mezijinn And when the critter crashes into anything, it backs away and speeds off in another direction. Troubleshooting a wayward mousebot. Install the op-amp chip and main control circuit. Newsletter Stay inspired, keep making.


Super Awesome Sylvia’s Mousey the Junkbot


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