An apparatus includes a circuit to receive power and data over a communication medium, where the circuit is to separate the power and the data. An electronic switch couples the power output by the circuit to a downhole electrical component for use in a well. According to other implementations, an electro-hydraulic actuator includes an outer housing defining a first hydraulic chamber and a second hydraulic chamber, where a seal for one of the hydraulic chambers is achieved without use of an elastomeric seal.