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About 12 Volt 30 Amp Circuit

2017-08-08 21:44  
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This article describes is about a 12-volt 30 Amp circuit. The circuit is relatively simple, it is easy to grasp. Here you'll read the following diagram combine text it! Input transformer is probably the most expensive part of the entire project. As an alternative, a pair of 12 Volt car battery can be used. Input voltage to the regulator must be at least a few volts higher than the output voltage (12 v), so that the regulator can maintain its output. If a transformer is used, then the rectifier diodes must be capable of passing a very high peak forward current, typically 100 amps. IC 7812 or less only by the output current of 1 amp, the rest being provided by the transistor outboard. As the circuit is designed to handle a large number of 30 amps, then six TIP2955 is connected in parallel to meet this demand. Dissipation in each power transistor is one sixth of the total load, but still need to have sufficient heat dissipation. Maximum load current will generate maximum dissipation, so a very large heat sink is required. In considering a heat sink, it may be a good idea to look for is not a fan or water cooled heat sink. If the power transistors should fail, then the regulator must provide full load current and would fail with catastrophic consequences. A 1 amp fuse in the regulators output prevents protection. This circuit is typical of Kirchhoff's current and voltage laws. In short, the currents into a node must be equal to the current left end, the voltage at a cycle must be equal to zero. For example, in the figure above, the input voltage is 24 volts. 4 volts is dropped R7 and 20 volts across the regulator input, 244-20 = 0. In the output: - the total load current 30 amps, regulators supply 0.866 and 4.855 amperes per six transistors, 30 = 6 * 4.855 0.866. 4.86 the contribution of each power transistor to the load. In the base current is about 138 mA / transistor. 35 is a DC current gain of the collector current of 6 amps is required. This is a good TIP2955 within the limits. Resistors R1, R6 include stable and prevent current manufacturing tolerances submerged DC current gain will be different for each transistor. 100 ohm resistor R7 and development 4 volts, the maximum load. Power consumption is therefore (4 ^ 2) / 200 or 160 mW. I recommend using 0.5 watts resistor to R7. Input current regulator is fed through the emitter resistor and the base of the power transistor emitter junction. Again using Kirchhoff's current law, 871 years of Ma Ying-jeou regulator input current from the base chain and the 40.3 mA flowing through the 100 ohm resistor. 871.18 = 40.3 830.88 years. Current regulator itself can not be larger than the input current. You can see that the regulatory bodies attracted only about 5 mA, should run cold. If you want a thorough understanding of the principles of the circuit, I suggest you can go to find out the important components of the circuit: LM7812C  and TIP2955 . 

12 Volt 30 Amp PSU

 A simulated performance is shown below:


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