Mousebot is a simple bot that uses two "eyes" to sense light and then turns towards the light. A single large "whisker" is mounted on the front of the mouse to detect collisions. A collision with a wall will cause the mouse to reverse and turn then take off in another direction. This project is pretty cheap, if you have a mouse to use the other parts can be obtained for less than ten dollars.
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Step 1: Gather Materials and Tools
1 Ball Mouse
2 Small DC Motors
1 Toggle Switch
1 DPDT 5v Relay (Aromat DS2YE-S-DC5V works)
1 LM386 op-amp
1 2N3904 or PN2222 NPN Transistor
1 LED (any color)
1 1K Resistor
1 10K Resistor
1 100uF Electrolytic Capacitor
1 Audio Cassette Tape (you know, from the 80s...)
1 CD-ROM or Floppy Disk (for the bumper)
1 9V Battery Snap
1 9V Battery
2 or 3 Wide Rubber Bands
22 or 24 Gauge Wire (some stranded and some solid core)
Desoldering tool of choice
Superglue or epoxy
Hot glue gun and glue
Step 2: Scavenge some parts
Open up the mouse and locate the components that we'll be harvesting, the momentary switch and the infrared emitters (the clear ones).
Remove the PCB and desolder the push switch and both IR emitters.
Step 3: Prepare the case
Now use the Dremel to cut openings for the bump switch in the front of the mouse and motors on the sides.
The best Dremel bit to use for this is the short cylindrical type, it will cut a good right angle if the Dremel is held vertically.
Step 4: Make the wheels
Cut the rubber band and superglue it to the rim then wrap it around three times, adding superglue every half turn or so to keep it together. Cut off the leftover rubber.
Now glue another rubber band back to the one that you just wrapped. Complete one revolution and cut off the extra. Make sure to add enough glue to keep the outside rubber band on. Repeat the same process for the other wheel
Step 5: Layout the design and install the relay
Once we know where everything will go its time to get to the real work. Set down the relay and solder wires in an X connecting pins 8 to 11 and 6 to 9. (see pin labels on second image)
Then connect pins 1 and 8 with a wire along the side and add stranded wire to leads 8 and 9.
Solder the collector of the transistor (right pin looking at the flat side) to pin 16 and clip the lead short. Then connect the wire we soldered to pin 9 to the emitter (left pin looking at the flat side) leaving a little bit of slack.
Now glue the relay into the case. I have added two clipped leads to act as positive and negative voltage rails which will get rid of some clutter in the motor area. Use your razor knife to strip the shielding from the wire connecting pin 9 and the emitter and solder it to the - voltage rail. Then connect pin 8 to the + voltage rail.
Step 6: Install the bump switch
Connect the resistor on the switch to the base (middle pin) of the transistor and the wire from the ground side of the capacitor to the - voltage rail. Then connect the middle pin to the + voltage rail. To make your joints a bit more secure you can use heat shrink tubing to insulate the connections and bend the capacitor to the side to free up a little bit more space.
Step 7: Build mousebots brain
Now place the 386 into position and connect pin 4 to the - rail, pin 6 to the + rail and add stranded wire to pins 2, 3 and 5.
We are almost ready to connect the motors so solder some stranded wire to pins 4 and 13 of the relay. At this point your Mousebot should look something like the third picture on this page.
Step 8: Construct Mousebots top half
To create mousebots eyestalks twist two pieces of solid core wire together and solder the IR emitter to the leads on one end. Place the LED in the middle hole and connect the + lead to the 1k resistor.
Next use the diode check feature of your multimeter to find the - leads of the IR emitters and connect them to the - lead of the LED.
Step 9: Glue down the components
Step 10: Finish up making connections
Locate the wire coming from IC pin 2 (green) to the + lead of the left eyestalk and IC pin 3 (blue) to the + lead of the right eyestalk. Then wire the 1k resistor to the + voltage rail.
Hook up the battery by soldering the black wire on the battery cap to the negative voltage rail. Connect the red wire on the battery cap to the switch and then connect the switch back to the + voltage rail.
Replace the cover of the mouse and then cut a thin strip of your bumper material (CD) with the hacksaw. Attach the strip with epoxy or hot glue on one side so that wherever you apply pressure the button clicks. Once you have the strip attached give yourself a pat on the back, you're done.
Flip the switch and enjoy.