This circuit reproduces the dial noise in a small speaker. The transistor can be a general-purpose type. We found it in an 80's Electronic Design.
This power supply was found in the September 1989 issue of Radio Electronics magazine. The 2N3055...
I found this simple circuit from an English magazine from 1984. The circuit can be easily...
This voltage regulator for automotive use was found in a Radio Electronics from the 80s. The Q3...