My take on regulators

[Cauhtemoc]

I was experimenting with different regulators in Spice, and I came up with two versions. The first one is based on the POOGE regulator. The design is somewhat different, some values have been changed, and I use two transistors as a voltage reference. They are much quieter than zener diodes, and the small reference means that it can work well even at very low voltages. The parts for this regulator costs around $3, which is about the same as the original POOGE regulator.

Schematic is attached, I used transistors instead of diodes to simplify things.

[Cauhtemoc]

The second regulator is a cross between the POOGE and Walt Jung's super regulator. I use two transistors as a reference here as well, but I replaced the op amp with discrete components. I did not know how this would affect the performance, I mainly did this to lower the cost. The entire regulator can now be built for around $5.

[Cauhtemoc]

Attached is a simulation comparing the performance of various regulators. Green is an LM317, blue is an LT1085, red is the POOGE regulator found on ALW's website (here), cyan is my POOGE regulator, pink is the Sulzer regulator (with NE5534), dark green is the latest version of Walt Jung's super regulator (with preregulator and AD825), and orange is my super regulator.

Note that my POOGE regulator outperforms the Sulzer regulator and even rivals the Jung regulator at higher frequencies. Because of the low cost you can easily run two of them in series, this would lower the noise floor to below -200 dB. My super regulator performs around 60 dB better than my POOGE regulator, and running two of them in series would lower the noise floor to well below -300 dB.

Note that they are only simulations however, and as such they should be taken with a grain of salt. If anyone wants to build these be my guest.

[chalkandtalk]

These look great.

I'd like to build a reg2 to power a monica DAC. At the moment I'm using some 317's to drop 19V SMPS input to 12V out.

However, how do I work out R1,2,3, and 4?

cheers

Aidan

[Nordic]

Any broad voltage and current limit numbers?

[martin clark]

you can easily run two of them in series, this would lower the noise floor to below -200 dB. My super regulator performs around 60 dB better than my POOGE regulator, and running two of them in series would lower the noise floor to well below -300 dB.

If only life were that easy!

Unfortunately it isn't; you'll find that in real life you'll struggle to get below -120 to -130dB. All sorts of reasons why, all of them parasitic terms.

[Cauhtemoc]

Originally posted by chalkandtalk
However, how do I work out R1,2,3, and 4?

Output voltage is Vref * (R1/R2 + 1).

Vref should be about 1.34V assuming a voltage drop of 0.67V over each transistor. Try to keep the parallel resistance of R1 and R2 below 1k. Set R3 to the parallel resistance of R1 and R2, and R4 to series resistance of R1 and R2.

Originally posted by Nordic
Any broad voltage and current limit numbers?

That depends on the pass transistor. I chose a BD139 in the schematic above, but almost anything will work. The same applies to the small signal transistors. I chose 2N5087 and 2N5089 as they are common, but almost anything will work here as well. BC550 and BC560 might be easier to get ahold of in Europe.

[awpagan]

Or another very simple but effect circuit
by John Lindsay Hood


allan

[Nordic]

Any alternatives for 2n5087 & 9 ?

Does not seem to be a common item... not in RS catalog, or any of my local stock lists...

[SY]

Originally posted by awpagan
Or another very simple but effect circuit
by John Lindsay Hood

Something is missing there. This circuit will not regulate.