Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today. Observe the supply voltage range.
Found in an old Radio Electronics, this circuit uses common components today. The resistors of the IC...
Found in a 1965 General Electric circuit manual, this circuit uses SCRs from that time. Modern...
The modified Hartley oscillator, seen in figure 2, can generate signals ranging from 3 MHz to 10...