"I See Dead Pumpkins"

October 11, 2004

There's no better Halloween prop than a carved pumpkin. But Mark didn't like the idea of leaving burning candles unattended in his squash, so he built a battery-powered light source instead. For a realistic effect, he used a timer circuit that produces a pseudo-random timer pattern that makes two ultra-bright orange LEDs flicker, simulating a flame. The power source is four batteries at 1.5V or two 9V batteries wired in parallel for more current and longer glowing time.

"Scary Pumpkin" Parts List
Amt Part Description Allied Part #
1 Quad 2 input NAND Schmitt MC 14093BCP 568-3021
1 LM7805 voltage regulator +5V dc 288-0001
4 1N4148 diode 263-1538
2 Orange ultra bright 5 mm LED 505-9712
4 2N2222 transistors NPN 248-1004
1 Switch on-off 855-1099
1 Enclosure plastic 3 x 2.5 x 1.5 736-7404
4 Capacitor ceramic 104, 0.1 F 881-3486
1 Capacitor electrolytic 100F 852-7029
4 Trimmer Potentiometers 754-2719
Additional parts required: 18-2 stranded power wire (5 ft), 9V battery and straps, plastic drywall anchor screw, assorted resistors

For Mark McCuller's instructions on how to create your own "scary pumpkin," click here.

To view a schematic drawing of McCuller's "scary pumpkin," click here.

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