Electronic Keys & LocksLights and Display Board Circuits

Low-drop A.C. Switch for 12 V Halogen Lights Schematic Circuit Diagram

Challenges with Relays in Alternating Voltage Switching

Relays, due to their inertia, power consumption, contact wear, and size limitations, are not ideal for switching alternating voltages. Additionally, they are unsuitable for deployment in phase control circuits. Replacing them with triacs may pose challenges due to the forward voltage drop across these devices, necessitating careful consideration in their application.

Enhancing Light Bulb Performance with Halogen Technology

Halogen light bulbs utilize a halogen gas to enhance both light output and rated life, distinguishing them as a subtype of incandescent lamps. Renowned for their moderately high efficiency, quality of light, and extended rated life compared to regular incandescent lamps, halogen light bulbs offer improved performance and durability in various lighting applications.

Low-drop a.c. switch for 12 V halogen lights Schematic diagram

Enhancing Efficiency with Anti-Series-Connected SIPMOS Transistors

To overcome the need for a control voltage in anti-series-connected SIPMOS transistors, the circuit utilizes the inverse diodes of the transistors, as demonstrated in the diagram. This innovative approach resolves the control voltage requirement, making the system more efficient and practical.

Capacitor Charging and Load Handling

In the off state, when the optoisolator does not conduct, C1 charges during the negative half period through D3 and one of the inverse SIPMOS diodes. Depending on the load termination, the capacitor charges during the positive half period via D4 and the inverse diode of either T2 or T1. When the optoisolator conducts, connecting the voltage across C1 to the gates of T1 and T2 through R1, the circuit is activated. Diode D5 prevents excessive gate voltage. During the on state, C1 continues to charge through D3 and one of the SIPMOS transistors during the negative half periods.

Handling Inductive Load Switching

To suppress current peaks caused by inductive load switching, D2, along with D1 and D4, plays a crucial role. This configuration ensures smooth operation even in the presence of inductive loads.

Switching Capacities and Heat Dissipation Considerations

The circuit is designed to handle alternating voltages up to 45 V. Without a heat sink for the SIPMOS transistors, the maximum current should not exceed 3 A. For higher currents or regular switching of large inductive loads, employing a small heatsink becomes essential to maintain optimal performance and prevent overheating.



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