This is of a dual regulated that provides +12V and -12V from the AC mains. A regulator like this is a very essential tool on the work bench of an electronic hobbyist.
Transformer T1 steps down the AC mains voltage and diodes D1, D2, D3 and D4 does the job of rectification. Capacitors C1 and C2 does of filtering.C3, C4, C7and C8 are decoupling capacitors. IC 7812 and 7912 are used for the purpose of voltage regulation in which the former is a positive 12V regulator and later is a negative 12V regulator. The output of 7812 will be +12V and that of 7912 will be -12V.
IC regulator 78xx
IC regulator 79xx
Note:
- Use Transformer 15-0-15 V, 1A secondary step-down transformer.
- Capacitor C1,C2,C5 and C6 must be rated 50V or more.
IC regulator 78xx (7812) Description
The LM78XX series of three terminal regulators is available with several fixed output voltages making them useful in a wide range of applications. One of these is local on card regulation, eliminating the distribution problems associated with single point regulation.
Maximum Ratings
- Input Voltage (VO = 5V, 12V and 15V) : 35V
- Operating Temperature Range (TA) : 0°C to +70°C
- Maximum Junction Temperature : 150°C
- Storage Temperature Range −65°C to +150°C
- Lead Temperature (Soldering, 10 sec.)
IC regulator 79xx (7912) Description
The LM79XX series of three-terminal negative regulators are available with several fixed output voltages, making them useful in a wide range of applications. Each type employs internal current limiting, thermal shutdown and safe operating area protection, making it essentially indestructible.
Maximum Ratings
- Input Voltage (VO = -5V, to 15V) : 35V
- Operating Temperature Range (TA) : 0°C to +70°C
- Maximum Junction Temperature : 150°C
- Storage Temperature Range −65°C to +150°C
- Lead Temperature (Soldering, 10 sec.)
