Help to understand and build regulated power supply

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Uylum

Member
Joined 2013
#1
ive got some toroidal 24v 200va dual windings

ive got 20 of them could not throw them away..
i have some elektronic knowledge.
i want to build power suply for an amplifier.


ive been looking at

13.8V 20A linear power supply


i like the design but i vant higher voltage. up to 40v

can someone help me with this?




and can i put transformers in parallel and series for higher voltage and va?





 
#2
> 24v 200va dual windings

24V AC to rectifier and capacitor will peak at about 35V DC. Two such schemes makes +/-35V DC. This is good for almost 70 Watts Sine in 8 Ohms. So one channel at 8 Ohms solid or 4 Ohms mildly saggy (maybe 110 Watts).
 
#8
Not sure what you mean by 'voltage divider', but a couple resistors, a zener, small electrolytic, and a pair of lowly 1N4148's (just to keep the inputs within the '741s power supply range) should be all you'd need to add. And a long list of op amps aren't that keen on supply voltages higher than 36V, including most of the popular ones.

The bigger issue (for me, at least) is 'are you planning to use this very tightly regulated, high-current supply for the main rails of an audio power amp?'

Because we usually don't regulate the high-current rails that supply the output stage -- just too much loss in efficiency.

Cheers
 
#12
One other item I don't think we've covered is .. Are you planning Class A/B or something different? Because if your plan is Class A, the power draw is constant -- virtually nothing to be gained by regulating.

Others may (probably will!) disagree. But if you're willing to expend that much energy as heat, why not just go with Class A?

Cheers
 
#14
Most regulator IC's need a few volts higher supply, roughly 5v anymore and the IC dies after a while even with a big heatsink. With 28v out of the tfmr unloaded, call it 25v loaded you'd need to loose about 6v which you could do with a resistor before the regulator, not ideal.

The best way to find out is to build a circuit and test it, make a few mistakes, blow a few components up, you'll learn more that way.

Andy.
 
#15
If the lm741 is +-22v does it have to be between -22 and +22

or is it 44v difference

loks like im geting 0v to 28 -2v for diodes
going to start with lm741
got moast of the parts now.

does opamps have similar gain or do i have to change resistors for input if i change opamp to one with higher voltage tolerance?
 
#16
Number of channels (#) 1
Total supply voltage (Max) (+5V=5, +/-5V=10) 44
Total supply voltage (Min) (+5V=5, +/-5V=10) 10
Rail-to-rail No
GBW (Typ) (MHz) 1
Slew rate (Typ) (V/us) 0.5
Vos (offset voltage @ 25 C) (Max) (mV) 3
Iq per channel (Typ) (mA) 1.7
Vn at 1 kHz (Typ) (nV/rtHz) 30

But dont use it as its grossly been superseded by many better op amps.
 
#17
Forget that regulated power supply, is very poorly matched to your current raw voltages and in any case 13.8V for a power amp is ludicrous, plus power waste and heat will be horrendous.

Forget your preconceived ideas about regulated supplies on **Power** amplifiers, besides thers a reason 741 won´t work there, it does never ever expect such HUGE voltage.

Straight design and build an amplifier which is happy with +/- 35V supplies, period.

Putting a ton of transformers in parallel is useless if you will later waste power as heat, LOTS of it.

Again: forget that regulated power supply which is designed for car transmitters and such and in any case uses a WAY lower AC voltage transformer.
 
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