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|
|2||Orange ultra bright 5 mm LED||505-9712|
|4||2N2222 transistors NPN||248-1004|
|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|
|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.