This circuit can be used to slowly illuminate and fade a pair of red LEDs. The 100K potentiometer connected between pin 2 and pin 7 establishes the frequency which varies from a slow fade over several seconds to a very fast pulse. I used a pair of huge 10mm, super bright 5000MCD, LEDs.
PARTS LIST: 1458 Dual Op-Amp, 22uf capacitor, 3 - 47,000 ohm resistors, 100,000 ohm resistor, 100 ohm resistor, 100,000 ohm potentiometer, 2N3904 transistor, 2 - LEDs.
NOTE: Jim Kadel at Haunt Master Products sells a ready to use, fading eyes unit for $11.00. If you make your own, it will cost more and it will take an hour or two. I'm just bull-headed and had to build my own.