Power supplies are devices that produce AC or DC power. This grouping includes current sources, DC power supplies, AC-DC adapters, DC-DC converters, AC power sources, and DC-AC inverters.
Programmable logic controllers (PLCs) are the control hubs for a wide variety of automated systems and processes. They use a wide variety of inputs and outputs and provide network capability.
Signal transformers transfer information from one circuit to another by electromagnetic induction. They are used to increase or decrease the voltage from one side of a power transformer to the other.