I was at Abott's party store in Littleton, NH a couple days ago and saw a foam skull. Upon first glance it looked like your basic Halloween prop, until I saw the LEDs in its eyes. I immediately knew this would be the prop of a lifetime... with the sort of technology it was hiding in its cranium, the skull might be able to:
a) Scare the daylights outa the neighborhood kids
b) Dispense fortunes when it detected questions directed at it
c) Do the dishes, walk the dog and fetch me a beer
d) All of the above
With visions of sugarplums dancing in my head, I reached down with hands trembling in anticipation and flicked the "ON" switch.
Its eyes lit up.
they didn't even blink.
I was utterly devestated.
It was then and there that I decided to remedy this great injustice. I purchased the skull and began brainstorming.
Ten Redbulls later I hit upon an idea...
What if the skull could talk...
what if his eyes lit up while he talked...
so I set to work...
Step 1: Gathering Materials & Disassembling
note: double all amounts for stereo setup
1x foam skull with led eyes ($12.99)
1x 8ohm speaker (scavenged)
1x TIP31 npn transistor ($1.59 at radioshack, :( )
1x 1/8th inch mono phone jack (6 for $3.99 at radioshack :( )
1x stereo to mono 1/8th inch adapter ($2.99)
lots of thin wire (scavenged from a previously mutilated usb cable)
The first step is to remove the four screws holding the base on and snip the wires to the leds, leaving a stripable amount attached to both the LEDS and the battery box
Step 2: Build Circuit
Their are two essential, traceable circuits in the overall diagram they should go as follows
positive terminal of battery box unit goes to LEDs (in series)
negative terminals of LEDs go to transistor's Collector pin
transistor's Emitter pin goes to battery box unit's negative terminal
Positive terminal of phono jack goes to speaker and transistor's Base
Negative terminal of phono jack goes to speaker and transistor's Emitter