The phrase "a separate circuit" is correct and usable in written English.
It can be used in contexts related to electrical engineering, electronics, or discussions about systems that operate independently from one another.
Example: "To ensure safety, we need to install a separate circuit for the new appliances in the kitchen."
Alternatives: "an independent circuit" or "a distinct circuit".
In Italy, a separate circuit for air-conditioning costs as much as $400.
On a personal computer, the sound card is usually a separate circuit board that is plugged into the motherboard.
In 1832 Painted Post was set off as a separate circuit containing (as of 1837) Little Flatts, Painted Post, "Addison Village", West Addison, Erwin Centre, Campbell and Tioga.
The card is usually located on the computer motherboard or is a separate circuit board, but is sometimes built into the computer display unit.
The polymer conductance is controlled by voltage pulses between the source and gate electrodes in FET geometry, while the conductance state is read out by a separate circuit between source and drain.
As a dense-medium system requires the use of a separate circuit for the recovery of the dense medium, a flowsheet showing the key streams and unit operations for a dense-medium cyclone circuit has been provided.
But a third, separate circuit "won't get the media coverage they think they're going to get".
Each subpixel is controlled with a separate transistor circuit, which makes the circuits complex.
Waddell's team found that yet another neural circuit goes into action when the fly remembers the taste of water, a separate hardwired circuit distinct from the circuitry of the "Ah, water!" neurons.
An experienced cook, Meck believes, has a separate neural circuit set up for each task.
Dynamite, the usual explosive, is fired by electric blasting caps, energized from a separate firing circuit with locked switches.
