Design News has its latest “Gadget freak” how to up, build a fading LED for spooky projects – “Partial to things that go bump in the night, Bill built a circuit that slowly illuminates and fades a pair of red LEDs. It consists of two op amps, one producing a slow rising and falling voltage (3 – 6V) and the other functioning as a voltage comparator. In operation, a linear 3V ramping waveform is generated at pin 1 of the LM1458 IC and buffered with an emitter follower transistor stage. Make the rate adjustable by using a 100K potentiometer in place of the 47K resistor at pin 2. Install it in a skull as a Halloween prop or if spooky things aren’t your thing, use it as a fancy power indicator for a home appliance.” – Link.
Fading Eyes LED project