Case #73: Les Wears His Silicon On His Sleeve

By: 
February 27, 2006

Looking for cool way of wowing that special someone on Valentines Day/birthday/whatever? Build her a flashing heart made from LEDs driven by a programmable microcontroller. Les' gadget is simple to build and made from easily-obtainable parts. The unique thing about this design is the LEDs are in an X-Y matrix so each LED is addressable. This allows an unlimited combination of displayed patterns for the heart - not like some other designs out there! Source code and schematics are all available here and if you're not into hand wiring, even the PCB can be had for a small fee. Diamonds may be a girl's best friend but gadgets are forever.

Flashing Heart Parts List
Amt Part Description Allied Part #
1 9V Power Supply STA-9530A 928-9685
2 Ceramic Cap 27pF 881-5122
3 Ceramic Cap 100nF 507-0218
1 Crystal 12 MHz 895-0687
1 Diode 1N4148 263-1538
1 Eprom (optional) 24C16 652-0019
5 PNP Transistor BC557 431-0475
1 Rectifier 1N4002 266-0002
30 Red LED T-1 3/4 679-9981
1 Regulator 7805 263-0135
5 Resistor 2.2K .25W 832-0405
6 Resistor 120 ohms .25W 895-3139
Additional parts required: Atmel AT89C2051 MCU; Circuit board or perf board

For Les Grant's complete instructions to build your own Flashing Heart, click here .

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