This crystal or galena radio is one of the many versions available on this website. This is from a documentation from the 70s. The coil is formed by 50 + 50 turns of wire 28 in a ferrite rod.
August 2017 - Mouser Electronics is supplying Vishay's new high-speed, high-sensitivity...
This circuit shows how to add a 1st regulator to a source that already has a step for this...
This circuit is from a Maxim manual and can be used to power shields from batteries. The circuit...