This circuit was found in a 73 magazine for radio amateurs of the 90s. The circuit uses two types of indicators, the diodes are for general use. The power supply is 5 V.
Two operational are used on this triangular-rectangular oscillator suggested by Motorola in its...
This circuit from a Popular Electronics from the 90's can generate signals from 0.03 Hz to 3 kHz...
With 8 to 30 V power supply, the output power depends on both the voltage and the load. The...