This circuit was found in a Hands On Electronics from the 90s. It is intended to supply old tape players to batteries with a voltage of 7.5 V from the 12 V of a car battery or source.
This source for devices for automotive use was found in a 1985 documentation. The power...
We found this circuit in an old Popular Electronics. It is possible to light a common neon lamp...
This circuit has an opposite action to the previous one, triggering when light falls on the...