This transistorized stage has a high gain, being adjusted by VR1. The circuit can be used as an excellent audio preamp. We found this circuit in a 1996 English publication.
In the figure we have the circuit of a simple humidity sensor with the 4011. The circuit was found...
We found this receiver for the 144 MHz band in a European publication from the 1970s. The circuit...
We found this circuit in an ancient American documentation. It can be adapted to operate in other...