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.
In the circuit of the figure, when pressing S1 the sound varies according to the value of R2 and...
This 6-transistor Japanese radio from the 1960s used germanium transistors and had an output power...
November 2016 - Texas Instruments' new ISO773x triple channel digital isolators with 5,000 V...