We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the power supply which can consist of 4 batteries or a 9V battery. The basic circuit uses two-color LEDs.
The basis of this circuit is a National Semiconductor operational amplifier that functions as a...
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...
Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic...