This low power bass booster is from the 1977 National Semiconductor Audio Handbook. The circuit is powered by 6 to 9 V voltages and the feedback determines the enhanced bass range.
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....