Symmetrical power supply for power audio amplifiers + – volts with transformer, rectificators and filter capacitors
Power amplifiers that supply a reasonable potency request a power supply super dimensioned in agreement with the circuit. Most of the amplifying circuits requests a supply of the symmetrical type +-V. The schematic of the supply it not presents a traditional assembly of symmetrical supply regulated with transformer, rectificators and great filter capacitors.
The diodes for the circuit should be dimensioned in agreement with the amplifier to be used. The electrolytic capacitors should be of at least 10000µF for a good quality to be had in the audio, but in the plate he/she has space to place A good filtrate of the supply it is what guarantees the excellent quality of the wave in systems hi-fi. Audiophiles get to use a total of 4 capacitors of 22000µF, totaling 88000µF.
The resistors R1 and R2 are components of safety, because they discharge the great capacitors when the amplifier is turned off. C3 and C4 are capacitor’s bypass, and the nets RC R3/c5 and R4/c6 they reduce the inductance it sponges of the great electrolytic, that improves the acting of the supply in the discharges frequencies and the acting of the amplifier in the complex loads. The blue led indicates the operation of the supply and it should be placed in the panel of the amplifier. For safety of the circuit fuse should be used in the line of 220v in the supply and in the connection of the supply with the circuit of the amplifier.
The circuit of the supply can be placed in the same box where the potency amplifier be set up.
Transformer for the circuit of the supply
O value of the final tension, that it will feed the circuit, it can be calculated through the following formula:
Vf = (1,4 x Saw) 51; 0,5
Vf = final tension (DC)
I saw = tension of the exit of the transformer (AC)
In that way, if your transformer possesses exit (secondary) of 20+20 VAC, the final value of the tension that will feed the circuit it will be of approximately +/-28 VDC.
The choice of the ideal transformer for your amplifier will depend on the maxim tension of feeding of the circuit and of the necessary current.
Attention: that if you use a supply that supplies higher tension than the circuit of the amplifier needs the potency transistors or the circuit values of feeding tension, then if you use the minimum value he/she will have less potency, it will use a smaller heat-sink and capacitors with tension of smaller and cheaper work.
The potency of the transformer used in the supply
The potency of the transformer usually comes expresses in VA, is that the product between the tensions of the secondary and the current capacity. Being like this, a transformer that he/she has secondary of 25+25V and supply 4A total, he/she has a potency of 100VA (25×4). A recommendation for the amplifier in circuits of amplifiers well elaborated, as with integrated circuits, for potency of the transformer to consider 1,5 VA for each Watt supplied by the amplifier for each rolling up of the secondary.
Example: Transformer of 2x22Vef for an amplifier of 75 watts the potency of the transformer should be of 225VA.
Which transformer to use torodal or nucleus E+i.
When well built any one it can be used, the advantage of the torodal is that are more efficient, smaller and lighter than the transformers with nucleus E+I. they Also emit less EMI (interference electromagnetic). The disadvantage is that the transformer torodal is more expensive.
Where to get the transformer and the capacitor’s for assembly of the supply
They exist several suppliers of those types of electronic components that sell for the internet and they dispatch to every Country.
Suggestion of printed circuit board for assembly of the supply
Printed circuit board suggestion of assembly side of the components
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