As a power source for certain circuits, operational amplifiers often use low-power sources of several volts (12-15). To date, the most widely used voltage regulator is 12 volts, made using three-pin integral units. Their purpose is to obtain different voltages and electric currents at the output. The main components are integrated circuits of domestic production KR142EN8B and their imported analogues of the MC78xx and MC79xx series or just 78xx and 79xx.
Domestic and foreign types of stabilizersThe Russian integrated unit KR142EN8B (short name KREN8B) provides a normal output voltage of twelve volts.
Imported stabilizers of the above series have the following designations: the initial even number (78) shows the destination - the positive output current, the odd number (79) - the negative output voltage. The last two digits (12 or 05) indicate the magnitude of the output electric current. For example: 7912 - microcircuit - voltage regulator 12V with negative polarity, 7805 - microcircuit - similar unit, only 5 volts and with positive polarity.
The three-pin stabilizer, as its name indicates, has three outputs that provide connection to an external electrical circuit: input, output, and common. A common output is used to connect to the power supply housing (ground). The input and common outputs are used to supply the input voltage, and the working output is obtained on the outputs "output" and "common".
A voltage regulator of 12 volts will work normally if the input current at the maximum allowable load exceeds the output by at least 2.5 volts. In this case, the maximum input source should not exceed thirty volts. In addition, keep in mind that an increased input voltage gives a power gain, the 12V stabilizer starts to heat up. Accordingly, to prevent breakage, the use of a heat sink is necessary.
A standard power source is assembled from an electrolytic capacitor with a capacity of up to 10,000 μF, a half-wave bridge rectifier from diodes having a reverse voltage of 50 volts and a direct current of 3 A, a fuse (0.5 A). The voltage regulator itself is 12 volts - 7912 or 7812 (KREN8B).
Using such an assembly for the operation of the assembled device, it is necessary to arrange the electronic components so that the length between the mounting connections is the shortest and the removal of the radiator the largest. For cooling, it is best to take standard finned radiators with sufficient surface area, or metal plates.
Sources that use a 12-volt voltage regulator in their composition allow their use for powering various types of devices and units using TTL integrated logic circuits, including devices for automotive vehicles.