This circuit was taken from Maxim documentation from the 1990s. It can be implemented on the basis of modern operational amplifiers. Power supply doesn't have to be symmetrical.
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...