How to apply a voltage regulator of 12 volts

As a power source of certain circuits on operational amplifiers , low power sources of several volts (12-15) are more often used. To date, the most widely used voltage stabilizer 12 volts, performed using three-lead integrated units. Their purpose is to obtain at the output a different voltage and an electric current. The main components are integrated chips of domestic production KR142EN8B and their import analogues of the series MC78xx and MS79xx or simply 78xx and 79xx.

Domestic and foreign types of stabilizers

The Russian integrated unit KR142EN8B (abbreviated 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 - positive output current, odd number (79) - negative output voltage. The last two digits (12 or 05) indicate the magnitude of the output current strength. For example: 7912 - microcircuit - voltage regulator 12V with negative polarity, 7805 - chip - similar unit, only 5 volts and with positive polarity.

The three-output stabilizer, as its name suggests, has three outputs that provide connection to an external electrical circuit: input, output and common. A common pin is used to connect to the power supply housing (ground). The input and common terminals are used to supply the input voltage, and the output is output at the outputs "output" and "common."

The voltage regulator of 12 volts will work normally if the input current at the maximum permissible load exceeds the output voltage by at least 2.5 volts. The maximum input source should not exceed thirty volts. In addition, take into account that the increased input voltage gives a power gain, the 12V stabilizer starts to heat up at the same time. Accordingly, to prevent breakage, it is necessary to use a heat sink radiator.

A standard power supply is assembled from an electrolytic capacitor with a capacity of up to 10000 μF, a full-wave bridge rectifier made of diodes having a reverse voltage of 50 volts and a forward current of 3 A, a fuse (0.5 A). The voltage regulator itself is 12 volts - 7912 or 7812 (KREN8B).

Using a similar unit to operate the assembled device, it is required to locate the electronic components so that the length between the mounting connections is the smallest and the removal of the radiator is the largest. For cooling, it is best to take standard finned radiators with sufficient surface area, or metal plates.

Sources that use a voltage stabilizer of 12 volts in their composition allow their use for power supplies of various types of devices and units executed with the use of TTL integral logic circuits, including devices for automotive equipment.