Found in an old American documentation this FM modulator makes use of a varactor diode. The circuit can be easily implemented given the small number of components used.
Other operational amplifiers or voltage comparators can be used in this configuration which can be...
The basis of this circuit is a CA3130 operational amplifier. The transistor can be BC548, and the...
This fast Schmitt trigger operates at frequencies from 10 Hz to 100 Hz, with very short rise time....