This circuit was found in a Popular Electronics from the 90s. The transistors are general purpose, and the gain depends on the ratio between R2 and R1.
This short-range experimental transmitter emits a signal with many harmonics, without modulation. It can...
The LM380 is not a modern component and in some cases not easy to find. But if you have one you...
This is the analog part of the previous circuit with the pressure sensor for the altimeter. The...