Porto-Arc rectifier
3/4-rear view of “selenium*” rectifier lamphouse power supply for the RCA Arc 400 carbon-arc 16mm movie projector, showing the AC input, pilot light, and DC output.
*That's what the specification plate says; a peek through the grille with a flashlight reveals this unit was retrofitted with a pair of high-current silicon diodes mounted in heat sinks along with a large electrolytic capacitor to smooth the DC output.
Porto-Arc rectifier
3/4-rear view of “selenium*” rectifier lamphouse power supply for the RCA Arc 400 carbon-arc 16mm movie projector, showing the AC input, pilot light, and DC output.
*That's what the specification plate says; a peek through the grille with a flashlight reveals this unit was retrofitted with a pair of high-current silicon diodes mounted in heat sinks along with a large electrolytic capacitor to smooth the DC output.