0-30 Vdc Stabilized Power Supply

[ante]

Xenobius,

Welcome to this community!

Have you checked all connections and components for correct orientation and values?

Ante ::)

[Xenobius]

Thanks buddy and yes ALL IS perfect

I even put 3 fuses in it!

1. 3A with mains
2. 4A with secondry of transformer
3. 3A quick blow with output (incase of short circuit)

[ante]

Xenobius,

No, all is not perfect. We wouldn

[FireFly]

Could some one tell me if TI's 44V TLE214x op-amps would also be a good substitute for the TL081. I haven't got a complete handle on what all the specs mean yet. Thanks.

Datasheet:
http://focus.ti.com/lit/ds/symlink/tle2141a.pdf

[audioguru]

FireFly,
Yes, the 44V rated TLE2141CP is a good substitute for the TL081 in this project.

[Xenobius]

Xenobius,

No, all is not perfect. We wouldn

[Xenobius]

Ok People I fixed it :D

So take this as a tip:
IF IT varies the voltage from 23v to 35v ONLY, you got the Emitter and Collector of the 2N3055 Mixed UP lol..

Cheers!! when I arrive home I will post some pictures if the administrator lets me (until I arrive home I hope the administrator will already have posted if I can post pics or not)

10x

[audioguru]

Xenobius,
Good. I'm glad that you spotted and fixed your problem.
So the 2N3055's emitter-base junction was avalanching like a zener diode, in series with the base-collector junction. No matter what voltage the output of U2 was providing, the output could not follow it down.

Now you can remove those fuses which reduce the supply's performance:
1) Remove the fuse at the transformer's secondary, since its resistance limits the huge momentary current through the rectifiers when they charge C1, when the supply is loaded.
2) Remove the output fuse, since its resistance spoils the supply's regulation, when the supply is loaded. This supply has an adjustable current-limit so the fuse is not necessary.

Xenobius, could you please measure the voltage across R1/C1 without any load, and again set to 30V with a 3A load?

[FireFly]

And one more substitution please: 2N2219

I can't seem to locate these in a form easily attachable to a heat sink. Can someone suggest another model(s) suitable for this circuit that would be easier to find in a "heat sink form" such as TO-220?

Thanks again (for the umteenth time!)

[ante]

Xenbius,

Congratulations, Now everything is perfect. Can I ask you how the PSU performs, what is the maximum current @ 30Volts without voltagedrop?

Ante ::)

[audioguru]

Firefly,
Use a TIP29 or TIP31 to replace the 2N2219. Their TO220 case can be bolted to a good heatsink.
Since their current gain is less, change R15 to 100 ohms.

[Xenobius]

Hi all this is my PSU from inside.

How can I check the max current without a load?

thanks :)

[ante]

Xenobius,

First I have to say; It look very nice and tidy built, good job!
You can

[Xenobius]

Hehe thanks buddy for the compliments :D and sorry for the 50w resistor :p because I don't have one.

Here is another picture of it so even the people who are going to build it will have an idea of the layout :) (sorry for the dirt on the table but I was just drilling a PCB lol)

[ante]

Xenobius,

Exterior as well as interior it is a very nicely put together project. What about my suggestion for your next project?

Ante ::)

[Xenobius]

Right now I have 2 projects in mind the modification of that PSU to make it for 5Amps 30Volts and the Dummy Load.

Could you help me with both mate?

thanks

[ante]

Xenobius,

The mod has it

[Xenobius]

ok thanks for the dummy load .. I will work on it as soon as I start/finish the 5Amp PSU mate :D

thanks for now

[FireFly]

I'm aware that the filter cap is recommended to be much larger uF wise but I'm wondering about the voltage rating. The original part list called for a 50V cap. I may have found some large-enough, 250V caps. Would using caps with much higher voltage ratings do anything good or bad to this power supply? Should they perform as well as the same size cap rated at 50V? There must be some kind of trade off. Perhaps physical size or cost?

[FireFly]

Sorry. My last post should have said 450v caps rather than 250V caps.

[FireFly]

Sorry about my 2 previous posts. Please ignore my stupidity. I'm going back to bed now!

[ante]

Sweet Dreams ;D

Ante ::)

[audioguru]

To All,
See the other post about fixing this project before simply modifying it for 5A output.

[MonSSter]

Hi! ... i'm new on this forum so i have some maybe allreday answered questions... sorry ;)


i'm wondering if someone has made a 5Amp modification and use the LM338 insted of LM317? is there a new PCB for that or something? Tell me what u changed...

I'm also thinking to do a dual power supply. that's two adjustable power sources. Can I build two PCB's and then use transformer whit "double secondary connectors".. i hope u know what I mean... and use it like that whit no further modification...

Thank you!

[audioguru]

MonSSter,
Greetings, and welcome to our community.
We have discussed this project and have discovered some problems. We have another post that discusses how correct the problems and to increase its output to 5A. I have recently recommended changes that should allow this. There is a revised PCB layout there for my changes.The other post is here:
http://www.electronics-lab.com/forum/index.php?board=13;action=display;threadid=196

The circuit doesn't use a LM317 nor LM338 because they would not easily allow the circuit to do important functions:
1) Automatic change between voltage and current regulation.
2) 5A output at low output voltage. The LM317 and LM338 automatically fold-back their current limiting to protect themselves for their Safe Operating Area. The LM317 is guaranteed to give only 75mA, and the LM338 doesn't even have a guarantee, but is expected to give no more than 1A.
3) Voltage regulation down to 0V, and current regulation down to 2mA.

You have a good idea for a dual supply. With 2 separate transformer windings, the circuits will be completely independant.