0-30 Vdc Stabilized Power Supply

[AndyB78]

Hello all,

I have built and used this for a while. But my voltage ripple is not what it should be (I think it should be like a couple mV). Without a load the ripple it's about 70mV at a few hundred kHz. With a 12V and 1.65Amps light bulb the ripple is about 200-250mV at 50Hz.

As a modification from the original schematic, recently I have included 2 x 2N3055 in parallel with 0.33 ohms in their emitors and the filter capacitor is a 6800uF Nichicon.

Also the short circuit protection might not work correctly as after a few shorts the 2N2219A got burnt. But it could also be due to the fact that initially I had only 1 x 2N3055 on a very puny heat sink that melted my case with only a load of a few watts and apparently "provided" a short circuit between the pins of the 2N3055. After that I have mounted the pair of 2N3055 on a serious heat sink with proper isolation and now it holds easily the 3Amps with the 3055 tranzistors barely getting a few degrees hotter.

I probably should add that besides the power supply itself, the same transformer secondary powers in parallel (I had no room for a second transformer) a very simple LM317 auxiliary power supply for the panel voltmeter and a 12V fan.

Can anyone tell me what am I doing wrong regarding the ripple?

Thanks!

 

[AndyB78]

Hello,

I was wondering if this kind of ripple is something normal for this power supply. The information for this supply mentions a ripple under 0.001%.

Without load I get some 20mVpp (about 0.16%) and almost 4mVrms (0.03%) at 12V. 



With a significant load (some 12V * 1.6 amps light bulb) the ripple increases 3 times peak-peak and even more RMS: 

 

[yogi12]

Hi, what modifications I should do to have output 0-24V and 0-1 A? 

Thanks for help.

 

[simon munyua]

I plan to build this project:
0-30 Vdc Stabilized Power Supply With Current Control 0.002-3 A
http://www.electronics-lab.com/projects/power/003/index.html

My question is that I must supply this circuit exactly with 24VAC, or I can differ? So in what AC input voltage intervallum can I use this circuit?

Thank you,
Sala

any changes in the voltages mean changes in the circuit where you will need to change the capacitors and resistors to fit your new descriptions and requirements. I believe the values of resistors etc were calculated with consideration of 24V and not any other voltages. Thanks

 

[paul .a larner]

I am starting to build this,the kit came with tl081 opamps,i have some LF357n and some ua748cp opamps,what would be best to use?,thanks in advance.