Found in a 1967 Electronics World, this preamplifier uses an integrated circuit from that time, difficult to obtain today. The maximum frequency is 15 kHz.
Based on an Analog Devices LTC1540, this circuit consumes only 50 uA, serving to monitor the...
This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34...
We found this digital timer circuit in a 1994 publication. The power is supplied by 12 V, which is the...