This circuit uses an HA2400 consisting of 4 digitally controlled operational amplifiers. The circuit is from a Radio Electronics magazine from March 1980. The power supply must be symmetrical.
This circuit was taken from old American documentation. The transistors used make it possible to...
This oscillator uses a general-purpose transistor that can have BC548, BF494 or 2N2222 equivalents and...
This circuit of a 73 American magazine from the 1990s can generate multiple frequency signals from the...