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When testing a circuit, a source of voltage that is variable and has over voltage shutdown is veiy useful. In this circuit, Rl is adjusted to 1 to 2 V below the eventual shutdown threshold. R2 sets the trip voltage. When this voltage is reached, the circuit shuts the voltage to the circuit under test down. To reset, reduce Rl below trip threshold and depress reset switch SI. Over voltage Protection Circuit Diagram

This circuit protects your television as well as other electrical appliances from over-voltage. It uses operational amplifier µA741 (IC1) as a comparator. The unregulated power supply is connected to resistor R3 and preset VR1 through resistor R2. Zener diode ZD1 provides reference voltage of 5.1V to the inverting input (pin 2) of IC1.  Over-Voltage Protector Circuit Diagram The non-inverting input (pin 3) of IC1 senses voltage fluctuation in the mains. Preset VR1 is adjusted such that for mains supply below 240V AC, the voltage at the non-inverting terminal of IC1 is less than 5.1V. Hence the output of IC1 is zero and transistor T1 is in non-conducting state. At the same time transistor T2 conducts to energise relay RL1 to connect the mains to the load. When AC mains is beyond 240V, the voltage at pin 3 of IC1 goes above 5.1V. The high output of IC1 drives transistor T1 and transistor T2 stops conducting to de-energise the relay. Hence the appliance turns off. Preset VR2 is used f...

Using the FPF270X adjustable over-current protection IC can be designed a very simple adjustable current-limiting electronic project .FPF270X provide full protection to systems and loads from excess current conditions.Minimum current limit is adjustable from 0.4A to 2.0A.The input voltage range is 2.8V to 36V. Loads can be activated or deactivated with a low-voltage logic compatible ON pin. Fault conditions can be monitored using the error flag pin and/or the power-good pin. All devices clamp the load current so that it cannot exceed an externally programmed current level. An over temperature feature provides further device protection in case of excessive levels of power dissipation. FPF2700 responds to an overload condition that lasts longer than a fixed blanking period by turning off the load, followed by a retry after the auto-restart time.The FPF270X has an adjustable 0.4A to 2.0A minimum current limit set through an external resistor, RSET, connected between ISET and GND.A 4.7 F t...

A simple motorcycle battery over discharge protector circuit is explained in the following post. The circuit will prevent the battery from over discharging by the motorcycle headlamp whenever the mo-bike alternator is not enabled or is idling in the neutral mode in which case the battery is normally subjected to excess loads via the headlamp bulb. Motorcycle batteries are normally a lot smaller with their sizes and ratings compared to the vehicle and the usage. The main use of the battery present in mo-bikes is for enabling electronic start through a press of the given start button. However this small sized battery also has to undergo further stresses while operating excess loads such as the horn, the indicator lights, the tail light and the brake light. Even though the above loads mostly tend to depend on the motorcycles battery power, these do not affect the battery charge level significantly. The one that truly affects the battery is the motorcycle headlamp, which when switched O...