This analog volt-ammeter was found in an Electronics World of 1968. It makes use of a 0-1 mA analog milliammeter. Accuracy depends on the components.
This well-known siren configuration using complementary transistors is from a 1980s documentation. The...
This circuit was found in a Popular Electronics from the 90s. Transistors are general purpose...
This generator is more complete than the previous one, being able to generate pulses as indicated...