This high impedance circuit was found in 1967 documentation by Ferranti. The original operational amplifier is from that time. The circuit can be implemented with modern equivalents.
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...