Super Regulator, collecting the facts

[jackinnj]

I got an AP a long time ago -- it's being upgraded. I sold off a bunch of ham radio equipment to pay for it! I also have a Tek SG5010/AA5001 which went begging a couple years ago. It's almost, but not quite as good as the AP2022.

[janneman]

Originally Posted by jackinnj

When I get my analyzer I will measure the impedance "in situ" -- figure that you've got a strand of #20 awg wire 4" long.

I also received PA's super reg boards yesterday and will run them through their paces. He enables the flexibility to use both the LM329dz or TL431.

Would be interesting to see how your measurements compare with our originals.

jd

[jackinnj]

Just one measurement so far -- a Fairchild LM317 WITHOUT its adjust pin bypassed, using CCIR filter measures 295uV -- with the adjust pin bypassed with a 100u/25V Panasonic this goes to 29.3uV. These numbers seem roughly consistent with the charts in AA 2/95. I gave the LM317 the benefit of the same 100u/25V Panasonic on the output since the Super Reg benefits from same.

The AD825 Super Reg (again CCIR filter) with no pre-regulator is coming in at 3.3uV, and the battery pack itself 1.5uV, this is about the residual of the Tektronix AA5001. The super-reg is bootstrapped and I put C5 across the zener as shown in the 2000 article.

[peranders]

If you have the opportunity it would be interesting to see how much noise an AD797 will generate. It would also be interesting to see if the noise gets lower if you filter the LM329 more.

... also LM431, how good is it?

[jackinnj]

I have some AD797's around -- it appears that the authors ditched the part as it was prone to some non-linear behavior in this application. When I made some tests with my HP3581, the AD797 was definitely quietest.

fwiw, a small tantalum cap on the adjust pin (6.8uF) had about the same effect of knocking down the noise as a 100uF electrolytic for the LM317 -- but tantalum's have this unfortunate problem of going short when they die.

[peranders]

It's also better for the environment to avoid tanalum

[jackinnj]

PA sent me a couple of his boards to check out. I also got another set of Old Colony Boards -- I have yet to run the impedance tests on PA's, but here are some noise results I ran last night:

PA Regulator -- Gold IC socket for error amp -- LM329 Reference:

P-A SR AD825-- on Aries AD797 LT1028
No filter 15.14Uv 5.67uV 6.95uV
A-Weighted 2.38 1.03 1.00
CCIR-486 6.40 2.04 2.02
CCIR-2K(Avg) 3.03 0.941 0.921
22-22K 3.52 2.37 1.70

Jung-Didden SR
No filter 28.60 8.75 19.96
A-Weighted 4.52 1.63 1.06
CCIR-486 12.50 4.20 2.91
CCIR-2k(Avg) 5.91 2.07 1.43
22-22k 5.19 1.77 1.29

The voltage source was a battery, and everything is contained in an Oreo cookie tin. The socket on PA's boards raised the noise just a hair, so you would probably best just soldering in the IC of your choice. I was pleasantly surprised by the performance of the LT1028, but note that the wideband noise is higher -- there is no evidence of oscillation. LT1028's and AD797's are selling at around the same price these days.

I only had WIMA 100nF 100V -- which are a bit of a tight fit -- on the board. 63V polyesters would probably work better.

[peranders]

You come with very good news and I really appreciate your work. Thanks. It feels good also that my boards not only looks good (according to myself ) but it's interesting to see that my 4-layer board is a tiny bit better than the Jung/Didden design but if you want to be really sure the same active parts should have been used.

[Pano]

Hey guys - I have some "super regulator" questions, but it's not this same circuit. Just and op-amp looped around.
Can I thread crash, or put it somewhere else?

[jackinnj]

Put up the circuit -- there are lots of variants. If it doesn't fit the moderator can always move it.