In addition to producing a pulse sequence on the LEDs, this 1986 circuit also produces a tone sequence. The LM556 circuit consists of a double 555. The supply can be made with voltages from 6 to 9 V.
In addition to producing a pulse sequence on the LEDs, this 1986 circuit also produces a tone sequence. The LM556 circuit consists of a double 555. The supply can be made with voltages from 6 to 9 V.