With an 18 V input, this regulator was found in Philips documentation from the 60's. The transistors are from that time. The power transistor must have a heatsink.
This circuit converts a high impedance signal into low impedance. The circuit has unit gain and...
This project came out in an article of mine (Newton C. Braga) in the Popular Electronics magazine of...
This variable oscillator with crystal was found in a Popular Electronics of the 90s. The circuit uses...