This circuit is from an Electronics World of 1968. The transistors are of the time and the power is supplied with a voltage of 40 V. The circuit is high fidelity.
We found this circuit in a 2002 documentation. The circuit must be powered by a symmetrical source...
This circuit is from a 1988 American magazine, but it is still up to date due to the components it uses. It...
In this circuit of a 1991 publication, we can use the 2N2646 unijunction transistor and the sensor...