This circuit is from a Popular Electronics from the 90s, consisting of a repeater relay for remote control of TV, which today can be done by Wi-Fi or other simpler resources.
This circuit uses a ceramic transducer to emit ultrasound whose frequency depends on C2. The...
We found this Nicad cell charging circuit in an English publication from the 1970s. The circuit can...
This small transistor radio was published in Radio Electronics magazine in November 1957. The...