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                                           This is the circuit diagram of 5V DC regulated power supply which featured with short circuit protection system. There are 2 kind of output that are regulated 5V DC with short circuit protection and without circuit protection. The main circuit is protected from any damage due to short-circuit in the additional power supply circuit by cutting off the derived supply voltage. The derived supply voltage restores automatically when shorting is removed. An indicator LED is utilized to show whether short-circuit exists or not. Power Supply Block: This circuit works just like the ordinary DC power supply adapter, in the main power supply circuit, 230V AC from main home electric source is stepped down by transformer X1 (230V AC primary to 0-9V, 3...

The most simple polarity protection tehnique is to connect a series diode to the power line input. The diode conducts only when the power supply protection is correct. But the incovenient is that at higher current levels, the voltage drops and power loss of the diode affects the power level adversely. This polarity protection circuit is dimensioned for 12 V power supplies and avoids the voltage and power loss problem. By correct polarity, the current flowing to the D1 and the relay coil causes the relay contacts to activate. The NO contact closes powering the electronic device. The NC contact opens and the current supplying the relay coil is reduced to a low level just enough to maintain relay activation. source [link]

This is a simple Over - Under-Voltage Protection Of Electrical Appliances. This circuit protects refrigerators as well as other appliances from over and under-voltage. Operational amplifier IC LM324 (IC2) is used here as a comparator. IC LM324 consists of four operational amplifiers, of which only two operational amplifiers (N1 and N2) are used in the circuit. Over - Under-Voltage Protection Of Electrical Appliances Circuit Diagram The unregulated power supply is connected to the series combination of resistors R1 and R2 and potmeter VR1. The same supply is also connected to a 6.8V zener diode (ZD1) through resistor R3.Preset VR1 is adjusted such that for the normal supply of 180V to 240V, the voltage at the non-inverting terminal (pin 3) of operational amplifier N1 is less than 6.8V. Hence the output of the operational amplifier is zero and transistor T1 remains off. The relay, which is connected to the collector of transistor T1, also remains de energised. As the AC supply to the ele...

This is an electronic fuse that protects the load against short circuit. Project Description Relays must be chosen with a voltage value equals to the input voltage. Don’t omit using the 100uF capacitor with appropriate voltage value with respect to the input voltage. If you can’t provide, you can use C106 instead of BRX46. You can adjust the current with using 10K potentiometer. If you will use the fuse with very high currents, lower the 0R6 5W resistor value (ex. 0R47, 0R33, 0R22 or 0R1). Watt value of the resistor should be increased also.

This is the circuit diagram of 5V Regulated Power Supply circuit, featured with over voltage protection. The circuit is based regulator chip 7805; Thyristor SCR 2N1595 and Dioda Zener 1N3997 for overvoltage protection circuit. The 5V regulated power supply is apply 74LS series integrated circuits which has to be really precise and tolerant of voltage transients. These IC’s are simply damaged by brief voltage spikes. A fuse will blow when its electric current rating is exceeded, but requires several hundred milliseconds to respond. This circuit will react in a few microseconds, triggered when the output voltage exceeds the limit of the zener diode. This circuit uses the crowbar process, where a thyristor is employed and short circuits the supply, causing the fuse to blow. This can take spot in just a few microseconds or less, and so provides a lot greater protection than an ordinary fuse. If the output voltage exceed 5.6V, then the zener diode will conduct, switching on the thyristor ...

This is a very interesting Protection speakers Stereo Circuit Diagram , it makes the protection of speakers in case of a short or overload in the output. This scheme now includes two audio channels (stereo), it uses relays to cut the speakers circuit sound output. In equipment sound power, is common to burn transistors or output modules, this can cause damage to the speakers home voltage equipment is sent to the output, this circuit just protects the speakers of this tension.  Protection speakers Stereo Circuit Diagram