BATTERY SAVER CIRCUIT OVERVIEW
This circuit acts as an Under-Voltage Lockout (UVLO) with hysteresis. It prevents a battery from over-discharging by disconnecting the load at 8V and reconnecting it only after recharging back up to 9V.
Leave the potentiometers where they are set, and adjust the voltage down to 8V and up to 9V. Watch the output snap off at 8V and crisply snap back on at 9V..
1. FUNCTIONAL BLOCKS
• VOLTAGE REFERENCE: The 3V Zener diode at the bottom left creates a stable ~2.9V baseline for comparison.
• VOLTAGE DIVIDER: The 3.82 kOhm and 6.18 kOhm resistors on the left scale down the incoming battery voltage.
• COMPARATOR WITH HYSTERESIS: The central Op-Amp processes the thresholds. The 200 kOhm and 800 kOhm positive feedback loop shifts the trigger point to create the 1V gap between the 8V cutoff and 9V turn-on points.
• OUTPUT SWITCH: The N-Channel MOSFET on the right turns on/off to connect or isolate the 100 Ohm load.
2. KEY COMPONENTS
• OP-AMP: Configured as a comparator to handle switching logic.
• N-CHANNEL MOSFET: The main electronic switch handling the load current.
• ZENER DIODE (3V): Creates the static reference point for accuracy.
• FEEDBACK RESISTORS (200k / 800k): Defines the 8V/9V switching hysteresis.
• LOAD RESISTOR (100 Ohm): Represents the electronic device being powered.
• GREEN INDICATOR LED: Visually displays whether the load is active.
• RED INDICATOR LED: Visually displays whether the load is inactive.
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