[GreenKeys] AC/DC power sources

[Jeffrey D Angus]

AC/DC power supplies.
Also known as "transformerless" equipment.

A single diode and a filter capacitor will make a nice DC supply
voltage in the neighborhood of 120 to 150 VDC. Except that
the common or return of said power supply is connected to
one side of the AC line. Moderately safe _IF_ it happens to be
the neutral side.  Not so safe if the return side (exposed metal
parts) are on the hot side of the AC line.

This is why any decent shop working on vintage radio equipment
with a "hot chassis" is equipped with an isolation transformer
so it doesn't matter which side is which, and the chassis can be
safely connected to the safety ground while testing.

However, It needs to be said that 120 VDC, even if properly
isolated from the AC line (typically with a transformer type
supply,) still has the potential of a lethal shock hazard.

Jeff-1.0
wa6fwi