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.
This circuit is from the Radio Electronics magazine of May 1984. With it, it is possible to...
A VCO or voltage-controlled oscillator, which uses only two of the LM3900 amplifiers, is shown in the...
This is one of the many versions of amplifiers with LM386. This was achieved in an old publication (1981). The...