This amplified speaker is from a Radio Electronics from September 1988. The power integrated circuit is from that time and the other components are still common today.
This circuit was found in a 1967 EEE. The transistors are from the time and can be tested...
Found in an old neon lamp applications manual, this circuit directly triggers an SCR. R and C...
This circuit was obtained from an English documentation from 1995. The operational amplifier has...