What is the purpose of connecting a diode across a DC-operated relay coil?

The purpose of connecting a diode across a DC-operated relay coil is to reduce inductive kick. When the relay coil is energized, it creates a magnetic field. However, when the coil is de-energized, the collapsing magnetic field generates a back electromotive force (EMF) or voltage spike, known as inductive kick, which can potentially damage electronic components or create electrical interference in the circuit.

By placing a diode in parallel with the relay coil, the diode allows the current generated by this back EMF to flow through the diode itself instead of causing a voltage spike. This current provides a path for the energy to dissipate safely, effectively clamping the voltage to a level that won't harm other components in the circuit. The result is not only protection for sensitive electronics but also enhanced reliability in the relay's operation.

Other options like eliminating relay chatter or increasing magnetic pull do not address the fundamental issue of voltage spikes caused by inductive kick. Maintaining a constant DC drop across the relay is unrelated to the diode's function in this scenario. Thus, reducing inductive kick is the primary and correct purpose of connecting a diode across a DC-operated relay coil.