Found in a Philips publication from the 1970s, this circuit uses a DO040, which is difficult to obtain today. The circuit is powered by 12 V on pins indicated in the diagram.
Found in Popular Electronics from the 90s, this circuit can be used as a warning shield for...
This circuit is from a Popular Electronics from the 90s. The circuit requires extreme care in use, as...
This circuit was found in a 90s Popular Electronics. The frequency is determined by R3 and C1 that...