AC to DC Converter with Automatic Battery Cut-Off Circuitย
Overview:
The Smart AC to DC Auto Cut-Off Power System is an efficient electronic project designed to convert high-voltage AC into regulated DC and automatically disconnect the load when a predefined voltage level is reached.
The system uses an LM358 Operational Amplifier as a comparator to monitor voltage levels and a MOSFET for switching operations. A regulated power supply using a 7805 voltage regulator ensures stable operation of the control circuit.
When the voltage exceeds the set threshold, the system automatically cuts off the output, preventing overcharging or damage. This design ensures safe, reliable, and efficient power management for various applications.
Key Features:
Converts 220V AC to regulated DC output.
Automatic voltage cut-off functionality.
Adjustable cut-off level using potentiometer.
Fast response using LM358 comparator circuit.
MOSFET-based efficient switching system.
Stable 5V control supply using 7805 regulator.
Low-cost and easy to implement design.
Main Components:
Step-down Transformerย (converts 220V AC to low-voltage AC.)
Bridge Rectifierย
Filter Capacitorย
7805 Voltage Regulatorย
LM358 OP-Ampย
Potentiometerย
MOSFETย
Resistors & Capacitorsย
Battery / Loadย
Working Principle:
The system starts by stepping down the 220V AC supply using a transformer. The AC signal is then converted into DC using a bridge rectifier and filtered using a capacitor.
A 7805 voltage regulator provides a stable 5V supply to the control circuit. The LM358 operational amplifier works as a comparator, where it compares the input voltage with a reference voltage set by the potentiometer.
When the input voltage exceeds the preset threshold, the LM358 output becomes HIGH. This signal drives the MOSFET, which turns OFF the load or charging path, effectively cutting off the power.
When the voltage drops below the threshold, the output becomes LOW, and the MOSFET turns ON again, restoring the connection. This ensures automatic and continuous protection.
Applications:
Battery charging systems with auto cut-off.
Over-voltage protection circuits.
Solar charging systems (basic implementation).
Power supply protection units.
DIY electronics and automation projects.