0-30V Stabilized Power Supply

[audioguru2]

I have posted the latest schematic and parts list many times.
There is a thread about it but I am busy now and will find it later today.

 

[redwire]

Here is the latest  parts list I have.  Not sure if it matches Audioguru's list,  but if it doesn't that's what this forum is all about.

PS_Parts_List_10-11-09.pdf

 

[mendimano1]

Thanx Redwire i will veate litle bit more for any post fom audioguru beafore i start building the power supply, tell me if this part list that you have posted goes with this schematics, and if you could tell me some other tips and sugestions since im planing to build an 5 amps version. Regards ;D

 

[mendimano1]

P.S  this schematics ;D

View attachment 40641

 

[redwire]

Yes, it goes with the sketch you posted.    For the 5A version I would recommend the following:

1.    30VAC  7.2A  or higher  stepdown transformer
2.    R7 = 0.27, 10W resistor
3.    C1= 20,000 uf, 63V
4.    Q4, Q5 & Q6  (at least 3 paralleled ) NPN transistors on huge heatsinks.

Actually pretty minor changes since most of these parts are located off the PCB because of their size .  The basic PCB doesn't change much except to ensure the tracks are wide enough to handle the 5A.

 

[mendimano1]

Thanx again Redwire, since i have two capacitors of 10.000 mF 63 Volts can i conect them paralel and use them

 

[Jure_S]

Hi!

Does anyone have a gerber file or board file for original 0-30v Stabilized Power Supply described here http://www.electronics-lab.com/projects/power/003/index.html?

Thanks

 

[Hero999]

No I don't think anyone does and if they did, you'd need to be sure that it's for the latest version and that you can get hold of all the components with exactly the same footprint.

 

[mendimano1]

I think tat is a great idea from jure, if any one havs the gerber file of pcb from the original version we colud modified for the latest version, so im caling to anyone if havs the gerber file to post it, regards

 

[audioguru2]

The original project used many parts that are too small so they got too hot.

 

[nand1]

Cann I use an  C1 = 4700

 

[Hero999]

Cann I use an  C1 = 4700

 

[audioguru2]

Many of the parts in the original project are too small so they over-heat, especially the tiny 2N2219 transistor that is used for Q2. Even the transformer is too small so it also over-heats.
The transformer voltage is too low so the project will never produce 30V at 3A.
The opamps have a max allowed supply voltage of 36V but it is 38V or more in this project with the transformer voltage too low.

I think the main filter capacitor should be 12,000uF.

 

[Hero999]

Assuming. a 30V transformer, a regulator drop out of 6.4V (going from what you said), a rectifier loss of 2V and an output voltage of 30V with a 3A load, I calculate the minimum filter capacitance to be 6521

 

[audioguru2]

The 0.47 ohm current-sensing resistor has a voltage drop of 1.41V at 3A.
The transistors and U2 opamp have a range of voltage drop at 3A.

Also, the value of the main filter capacitor has a wide range.

 

[nand1]

i have a 25V 8,33A Transformator

25*1,41 = 35,25V ???

Changes:
C1 = to 4700

 

[Hero999]

You need a 30V transformer.

C1 needs to be at least 6800μF, preferably 10,000μF for 30V@3A out.

 

[audioguru2]

The original circuit uses opamps that have a max allowed supply voltage of only 36V and two of them also use the -5.6V negative supply. The 30VAC transformer will be 31VAC without a load and will produce an unregulated +42.4V supply. Therefore two opamps will have a total of 48V as their supply.

3A rectifier diodes will get too hot (they don't need to be 600V).
Q2 must be an NPN but a BD140 is a PNP. Use a BD139 instead on a medium size heatsink.
use two output tranaiators, each with a 0.33 ohm emitter resistor.
many of the resistors are too small and will get to hot.

That is why we modified the circuit to make it work properly and to make it reliable.

 

[nand1]

ok i hope i can find the MC34071 OPAMP

i will use max  30V@2A

how much Volt i can get with a 24V Transformer ?



i change the OPAMP to MC34071 if i can find it.
an change the 2n2219 to BD139 on a heatsink

I build 4 Supplys in a Box i can put all the BD139 on a Heatsink

will it work fine after changing Parts i hope the ripple is not to big

can i use the shematic on the main side ?

how shematic i have to use.. i have used this

 

[audioguru2]

We modified the circuit so that MC34071 or TLE2141 opamps can be used with a 28VAC or 30VAC transformer. If you use them in the original circuit then they will have a total supply voltage of 39.6V and will be fine since their max allowed supply is 44V.

But there are many other things wrong with the original circuit.
With your 25VAC transformer, 4700uf capacitor and a 2A load, the max output will be about 25VDC with a lot of ripple, maybe 23VDC with no ripple.