Found in an 1868 Mullard documentation this circuit has a dynamic range of 10 Hz to 25,000 Hz. Modern equivalent transistors can be used.
This increased voltage regulator is from a 1980 publication, but it can be mounted using a BD136...
This circuit activates a garage door by the car headlights car or a lantern. The circuit is from a...
This circuit was found in an Electronics Now from the 90's. The integrated regulator circuit and...