This circuit was found in a 1969 Mullard documentation. Used transistors can be replaced with modern equivalents. Output transistors may be BD135 and 136 with heatsinks.
This simple timer is from a 1998 publication. Other operational amplifiers can be used, and the...
Found in an Electronic Design from the 90's, this circuit uses an SCR according to the controlled power....
This circuit decodes signals received in SSB (Single Side Band) obtaining an audio signal for...