0-30 Vdc Stabilized Power Supply

[noworries2004]

HI
Does anyone have a copy of the PCB layout please?

 

[kye]

wow

 

[dracu_n_dulap]

Hello
Could you please tell me what's the value of the trimmers? because in the pdf schematic of the final version they have no value. Those are the only parts that i have left to buy, and i can't wait to get this psu working.

 

[audioguru2]

The final schematic has the value of the calibration trimpots. It is a PNG file type, not a PDF.
It is this one:

View attachment 40582

 

[mendimano1]

im posting the pcb and layout in acordence with audiogurrus schematic, im caling every one on noticing me about mistakes and any sugestions

layoutpcb.rar

 

[Erivanst]

Hi everyone, specially Audioguru.

I

 

[audioguru2]

Hi everyone, specially Audioguru.

IView attachment 40934

 

[Erivanst]

The TL081 opamp used for U2 in the original project has a problem called "Opamp Phase Inversion". If its input went too close to its negative power supply voltage (within about 3V) then its output suddenly goes high.

The new opamps do not have the phase inversion problem so Q1 is not needed.

Audioguru, thank you for your prompt response. I

 

[ZzsozZ]

Hi I am in need of your help. How do I parallel two 2N3055 power transistor? Is it looks like E-E, B-B, C-C are connected?

 

[audioguru2]

Hi I am in need of your help. How do I parallel two 2N3055 power transistor? Is it looks like E-E, B-B, C-C are connected?

The two output transistors each must have a 0.33 ohm/2W resistor in series with its emitter to allow the transistors to equally share the current. The other ends of the emitter resistors are joined at the output of the project.
They are shown on the latest schematic and described in the latest parts list. You should not make the project without having these important documents.

 

[bugmenot1]

Hi AudioGuru, this fine adjustment for corrent is correct?

 

[bugmenot1]

attached

View attachment 40935

 

[audioguru2]

I would never use a separate fine pot. It would always be in the wrong position.
Instead I would use a big knob for accurate leverage.

 

[mendimano1]

Big knob? can you explain audigur a litle bit the meaning of big knob ;D (sorry), and does this mean for bouth current and voltage

 

[audioguru2]

Big knob? can you explain audigur a litle bit the meaning of big knob ;D (sorry), and does this mean for bouth current and voltage?

A big knob has a large diameter so your hand can turn it easily a lot or a tiny amount. Because you can turn it a tiny amount then a fine tuning pot is not needed.

 

[msr2009]

Hello everyone!

I'm going to make this very nice power supply, mainly after lot of modifications to improve its quality!

I was thinking if is possible to use a 15+15 VAC xformer... but with a relay to switch beetween 15Vac or 30Vac to feed the AC input and keep it away from excessive heat...

The idea is to place a comparator on central pin of P1, if U is less than 5V (15V at out) relay remains OFF and feeds power supply with 15VAC at the bridge... if greather than 5V (15V at out) then the relay turns on and feeds the bridge with 30VAC.

What you guys think about it ?

Will the power supply works with 15VAC ? (maybe use lower value for 10V 1W zener?)

thanks!

 

[audioguru2]

With an input voltage that is much lower than the design needs, you must analyse each and every part value to see if the voltages and currents are too low. The negative supply voltage will probably be too low and will need to have its current increased to increase its voltage which will cause its parts to be hotter when the supply voltage is normal.

 

[huazhongwei]

I think 24V AC is a standard Voltage Output of common transformers, that's why this circuit was designed for this voltage. A few volts up or down(maybe +-5V) aren't going to produce any fault but it is recommended that you use a 24V AC transformer.
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[audioguru2]

I think 24V AC is a standard Voltage Output of common transformers, that's why this circuit was designed for this voltage. A few volts up or down(maybe +-5V) aren't going to produce any fault but it is recommended that you use a 24V AC transformer.

But the output of the project with a transformer that is only 24VAC is only about 25V at 3A, not 30V.
The opamps in the original project have a supply voltage that is higher than their max allowed voltage.

28V and 30V transformer are common in Canada and the US. Maybe also in europe.
44V opamps are also common.

 

[stang1]

Hey,

couldn't you replace the 2n3055 with an MJ2955? This would reduce the dropout voltage ... like this:

http://www.elektronik-kompendium.de/public/schaerer/kdarl2.htm

What do you think?