Voltage Regulator Failed

[danny_galaga]

29 minutes ago, facthunter said:

They don't use just a simple relay. It includes windings reacting to the voltage as well as Current flow, all spring tension adjusted, and it  modulates  by opening and closing the Points . Some times a  resistor is also across the Point  to minimize the current change. A cut out was used as well to prevent reverse current on shut down. Later Diodes do the same thing. They need cooling.  Nev

I used to be an auto electrician 😉

[Geoff_H]

Another technique is the same as inverter technology.   It uses switching using Mosfets.  If you use resistance for control a large amount of heat will be produced.  In essence the .Mosfet will switch on and when the output reaches the desired voltage the Mosfet will switch off.  It does this as often as the time for the outlet voltage to drop to a predetermined value.  On and off will be very quick at low power and very long at high voltage. Efficiency low at low power settings.