IC 7812&7912 Dual Regulator Power Supply Circuit

IC 7812&7912 Dual Regulator Power Supply Circuit

Voltage Regulators low ability burning IC 78W alternation acclimated in our chart is now so bargain they are an economical another to simple regulators NPN-stabilizers. In addition, they action the allowances of bigger regulation, accepted absorbed / abbreviate ambit aegis to 1000 mA blow and calefaction bottomward if the electricity disperses too. Indeed, is not the alone way for these drives can be damaged polarity is incorrect or boundless ascribe voltage. Regulators Alternation 78W to affectionate of break 8V ascribe voltage of about 35V, while the blazon 24v bear 40V. Of course, of course, that regulators will not assignment with such an important ascribe cogwheel achievement as it would advance to boundless ability is dispersed. All controllers will bear the 78W alternation 1000mA accepted best accepted ascribe cogwheel voltage achievement of beneath than 7V. Otherwise, too broadcast power, thereby bringing the blaze extinguished.

Two transformers were acclimated to footfall voltage 230-250V AC ascribe power. It articles ability transformers 6-0-6V accessory terminals. This achievement is fed into the rectifier and clarify capacitor. Filtered IC6 that served 3-pin voltage regulator that provides a adapted achievement + 5V. It is acclimated to accredit the DPM system. It additionally comes as the arrangement voltage antecedent temperature accuracy.

Other articles transformers with a accommodation of 12-0-12V at its accessory terminals. The centermost was accustomed as a bubbler in the antecedent case. The added two accessory terminals are fed arch rectifier complete application diodes. Achievement recovered is filtered application a capacitor C5 and C6 for aliment and IC7 IC. In-8 IC7, which are 3-pin regulators accommodate achievement voltage of ± 8V. These two voltages are arresting generator. TO-8V ability antecedent is activated to the temperature of the network, and the advertence voltage. It is additionally all-important to +12 V and-12V food for the accomplishing of operational amplifiers. This can be calmly done application a 12V zener diodes. The achievement of arch rectifier is absorbed to the +12 V and-12V, respectively, application two zener diodes. In the zener achievement is fed to the terminals of the operational amplifier supply. For supply

for operational amplifiers charge not be actual able in acclimation + 12V, the use of Zener diodes be costly.

For the testing of cyberbanking apparatus voltage aloft 50 V is required. This can be accomplished through quadruple the alternation tension. It consists of four diodes and four electrolytic capacitors. Unreasonable Administration Accessory 12-0-12V is affiliated to quadruple string. Quadrupled achievement of the ambit is 68V to ground.

7812+2N3055 High Power Supply Regulator

Using a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps. The design is shown below:
Notes:
The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) 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 100amps or more. The 7812 IC will only pass 1 amp or less of the output current, the remainder being supplied by the outboard pass transistors. As the circuit is designed to handle loads of up to 30 amps, then six TIP2955 are wired in parallel to meet this demand. The dissipation in each power transistor is one sixth of the total load, but adequate heat sinking is still required. 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 either a fan or water cooled heat sink. In the event that the power transistors should fail, then the regulator would have to supply full load current and would fail with catastrophic results. A 1 amp fuse in the regulators output prevents a safeguard. The 400mohm load is for test purposes only and should not be included in the final circuit. A simulated performance is shown below:




Calculations:
This circuit is a fine example of Kirchoff's current and voltage laws. To summarise, the sum of the currents entering a junction, must equal the current leaving the junction, and the voltages around a loop must equal zero. For example, in the diagram above, the input voltage is 24 volts. 4 volts is dropped across R7 and 20 volts across the regulator input, 24 -4 -20 =0. At the output :- the total load current is 30 amps, the regulator supplies 0.866 A and the 6 transistors 4.855 Amp each , 30 = 6 * 4.855 + 0.866. Each power transistor contributes around 4.86 A to the load. The base current is about 138 mA per transistor. A DC current gain of 35 at a collector current of 6 amp is required. This is well within the limits of the TIP2955. Resistors R1 to R6 are included for stability and prevent current swamping as the manufacturing tolerances of dc current gain will be different for each transistor. Resistor R7 is 100 ohms and develops 4 Volts with maximun load. Power dissipation is hence (4^2)/200 or about 160 mW. I recommend using a 0.5 Watt resistor for R7. The input current to the regulator is fed via the emitter resistor and base emitter junctions of the power transistors. Once again using Kirchoff's current laws, the 871 mA regulator input current is derived from the base chain and the 40.3 mA flowing through the 100 Ohm resistor. 871.18 = 40.3 + 830. 88. The current from the regulator itself cannot be greater than the input current. As can be seen the regulator only draws about 5 mA and should run cold.

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