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 1965 Philips circuit uses old company transistors like the BFY51 and BFY50. The circuit is...
This circuit with an operational amplifier was found in the magazine Radio Electronics of...
This trigger produces an output pulse when zeroing the input signal. The circuit is from a...