Random Flashing LED

Here is a random flashing LED circuit which is economical at just 1 mA while using a minimum number of parts. With two spare gates available in the 4093 (a 2-input Schmitt trigger NAND), a single IC could separately control two random flashing LEDs. A particular advantage of this design is that both the minimum and maximum periods of the flashes may be adjusted, and in this way the degree of randomness itself.