Dual Power Supply Circuit, for Computer Use, Electronic Goods, Certification : ISI Certified

Listing ID #961514

The Dual Power Supply Circuit gives regulated Dual output of ±5V to ±15V and is available at a reasonable price of Rs 380/-. One often realizes the need for power supplies, which provide dual positive and negative output rails. This is particularly true with circuits, which contain operational amplifiers. Such devices require closely regulated supply rails of typically ±5V, ±9V, ±12V or ±15V. Integrated circuit voltage regulators are available in a range of output voltages and usually feature internal fold-back current limiting as well as thermal shut-down. A simple method of meeting such a requirement is shown in figure. Here two fixed voltage regulators of opposite polarity, are used in conjunction with a dual secondary transformer and single bridge rectifier. The current rating of the regulators should be greater than, or equal to, the maximum load current. Circuits which are solely based on operational amplifiers rarely require supply currents in excess of 100mA and thus 78XX/79XX series regulators will usually be adequate. The IC number and transformer rating for different output voltages are given in table.
About the Circuit :
As shown in the circuit diagram, AC input is given through transformer. The transformer rating depends on the output DC voltage as shown in the table. The AC output voltage obtained from the transformer, is rectified through bridge rectifier designed using four diodes D1 to D4. Capacitors C1 and C2 are used to filter the AC signal. The rectified filtered output is given to regulator IC1 and IC2. The output of IC1 and IC2 gives the fixed DC voltage depending on the voltage capability. This output is again filtered through capacitor C5 and C6. LED D5 and D6 glows, which indicates positive and negative output.