Hall sensor compass (CB22345E)

We found this circuit in an English documentation from 1995. The Hall sensor used is from the time and the operational amplifier could be the 741.

Divider by 4 320 000 (CB12304E)
This circuit, obtained from ancient English documentation, produces a pulse every 24 hours when a 50...
Pulse Counter (CB18676E)
This digital pulse counter offers an LED indication. Its maximum frequency is of the order of 5...
Sine to Square Converter (CB4131E)
This circuit was found in an old RF documentation. The circuit cuts out the incoming sinusoidal...