all about wiring diagram

This project provides the schematic & the parts list needed to construct a simple DC Power Supply from an input power supply of 7-20 V AC or 7-30V DC. This project will come in handy in case you use plenty of batteries for your basic electronics project.

Two DC voltage outputs are available; is a fixed regulated 5V for TTL use. The other output is variable from 5V upwards. The maximum output voltage depends on the input voltage. The specified maximum input DC voltage to the regulator is 35V. The maximum input voltage must be two volts higher than the regulated output voltage.

The DC Power Supply circuit is based around the 7805 voltage regulator. Its only three connections input, output & ground & it provides a fixed output. The last digits of the part number specify the output voltage, e g. 05, 06, 08, ten, 12,15, 18, or 24. The 7800 series provides up to one amp load current & has on-chip circuitry to close down the regulator if any attempt is made to operate it outside its safe operating area.It can be seen that theres in fact separate circuits in this power supply. 7805 is directly connected as a fixed 5V regulator. The second 7805 has a resistor divider network on the output. A variable 500 ohm potentiometer is used to vary the output voltage from a maximum of 5V up to the maximum DC voltage depending on the input voltage. It will be about 2V below the input DC voltage.

The capacitor across the output improves transient response. The giant capacitor across the input is a filter capacitor to help smooth out ripple in the rectified AC voltage. The larger the filter capacitor the lower the ripple.

For tiny applications the heat sinks wont be needed. The tab on the regulator will dissipate 2W at 25 o C in air. (This is equivalent, for example, to an input voltage of 9V, an output of 5V & drawing 500 m A.) However, as your projects get bigger they will draw more current from the power supply and the regulators will operate at a higher temperature and a heat sink will be needed. You can basically add voltage & current meters to it and put it in to an appropriate plastic case connected to a transformer.

Trouble Shooting Procedure

An LED has been put in to the output of the fixed 5V regulator to indicate that the circuit is working. Poor soldering is the most likely reason that the circuit does not work. Check that all the soldering is done properly. Check that all parts are in their correct position on the PCB. Other items to check are to make sure that the regulators, electrolytic capacitor & bridge rectifier are inserted in the correct orientation.

This audio energy amplifier undertaking is based on LM1875 amplifier module from National Semiconductor. It can deliver as so much as 30W of energy the utilization of an 8 ohm load & twin 30V DC power provides. It is designed to operate with most outdoor parts with current limit & thermal shutdown protection features . Other features include high achieve, fast slew charge, huge energy provide vary, giant output voltage swing & high present functionality.

Summary of the audio amply-fire options:

25V Power Supply

The schematic beneath shows how the +25V DC & -25V DC are acquired. In order to provide power provide for two stereo amplifiers, a power transformer score of 80VA with 240V/36V middle tapped secondary winding is used. The secondary output of the transformer is rectified by using 1N5401 diodes along side four electrolytic capacitors to smoother the ripple voltage. A fuse & a varistor are related at the major enter to give protection to the circuit once morest energy surge.

Audio Amplifier Module

The +25V & -25V DC power provide are related to the audio amplifier module thru a 2A fuse with the peripheral tools shown in the schematic under. The audio enter signal to be amplified is coupled to pin one among LM1875 throughout the resistor R1 and electrolytic capacitor E5.

The output sign at pin four of LM1875 can be utilized to immediately drive a eight ohm loudspeaker. Resistor R6 and capacitor C5 prevent-the capacitance developed on the lengthy speaker leads from riding the amplifier in to High Frequency Oscillation.

A heat-sink with a thermal resistance ranking of one.4 Cecilius/Watt or better should be used or else the amplifier module will-be cut-off from operation because of the heat in an effort to build up in the directionwork of the operation of the amplifier. Take note that the warmth sink tab on the IC module is internally related to the -25V power supply hence it must be remoted from the warmth sink by the use of an insulating washer. If this isn't finished, the negative rail shall be briefed to ground.