Voltage regulators are used for lowering the input voltage to the desired output volgage.
Different types include:
The simplest and best known regulators are the 78xx and 79xx series, where xx is the desired output voltage. They have three pins: input, output and ground. 7805 will get you 5V on the output pin, as long as you supply an input voltage of at least 3V higher. 79xx Series are for negative output voltages, but they work the same. These “building blocks” are great for making a simple and stable powersupply. Transformer, bridge rectifier, capacitor, 78xx and voila, instant powersupply.
Important: always place a 100nF capacitor between the output pin and the ground pin. Other wise the regulator could start oscilating.
Output voltages: 05, 06, 09, 12, 15, 24
Input voltage: at least 3V higher than output voltages, max 30V.
Current: max 1A
Variants:
Basicly the same as the 78xx regulator, but ajustable. It also has three pins: input, output, ajust. A voltage devider (2 resistors) is connected to the output pin and ground to create a reference voltage. This reference voltage is connected to the ajust pin. The regulator will adjust the output voltage, until the reference voltage is 1.25V. By altering one of the resistors of the voltage devider, you can adjust the output voltage.
Output voltage: min 1.5V, max 37V
Input voltage: ???
Current: max 1.5A
Variants: