This circuit was found in documentation from the 1970s. However, it can be implemented with modern transistors such as 2N2222 for Q1 and BF494 for Q2. The crystal depends on the desired frequency.
This circuit was obtained in an English magazine of 1976 and can be assembled with equivalent...
This power source was found in an old Argentine publication from 1973. The transistor could be the...
This circuit can measure voltages from 0 to 10 V with a very high input resistance. The circuit is...