This preamplifier for phonographic capsules using FET was found in 90s American documentation. Consumption is very low. The power can be obtained from the amplifier circuit with which it works.
This circuit is from a 1980s Motorola documentation. The circuit can be made with modern...
This well-known circuit triggers a relay when light striking the phototransistor is cut off. The...
This circuit generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...