We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and has 8 digits. Changes can be made using a prescaler to reach higher frequencies.
In this amplifier, the supply voltage is 35 V and the input resistance is 2k2. Equivalent...
This high speed laser diode driver was found in a 1980s documentation. Power FETs can be replaced...
This instrumentation amplifier with differential inputs was found in documentation from the 90s....