A Photo Multiplier Tube is an AEC component
About[]
A Photo Multiplier Tube (PMT) is an AEc component of the phototimer circuit. The PMT uses a fluorescent screen to convert impinging x-rays into light. The light then strikes a photocathode which induces an electrical current from the light energy. Other case, the induced electrical current can be used to charge an electromagnet which pulls the main exposure switch open and terminates the exposure.
Reference[]