This circuit is from a 90s Radio Electronics. The resistors must be precision types and the transistor is a general-purpose type. The operational admits equivalent.
This circuit, from a documentation of the 90s, uses unusual operations today, but the...
This circuit is from a Radio Electronics from May 1994. In it we have the way to connect three 4017...
This circuit is from the 70's by A. Fanzeres. We kept the original text. It has already been said...