Furby Hijack

Step 4 Add Bump Sensors

Make bump sensors. This step is necessary if your furby will be driving around like mine. These bump sensors will keep the furby from driving endlessly into a wall.

buy some papermate mechanical pencils (as in picture #1)
snap the tip off of one.
yank out the spring (picture #2)
Solder an insulated electrical wire to one end.

get some pipette tips (this is what I used but any number of things could be used) as in picture #3

Get a thin (should fit inside the spring) stiff metal rod. I used a thin metal rod from a broken umbrella I found on the street. Solder an insulated electrical wire to one end (picture #4).

Stick the nonsoldered rod end through the pipette so that about half an inch protrudes (picture #5)

Stick the pipette/rod into the spring and bend the metal rod so that its tip touches the spring around it, and glue the pipette/rod base the the base of the spring (picture #6).

You're done. NOTE: this is a 'normally closed' bump sensor, so your PIC program should be waiting for a 0 on its IO pin to signify a bump (unlike the tongue and belly touch sensors of the furby which signify a touch by a 1 on the PIC IO pin).