kevin gilmore

goldenreference low voltage power supply

250 posts in this topic

10V reference on 13.5 v leaves only 3.5 v on the current source.  not sure that would give the lowest noise.

but you would have to try it

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Posted (edited)

oh 13.5v is for some out of date DAC boards. my main focus and the main project is the electrostatics amp. never deal with such high voltage gear. pretty anxious.

by the way, do we choose zeners by this rule?

LT1021-10: 9.1v zener

LT1021-7: 7.5v zener

LT1021-5: 5.1v zener

Edited by mtoc

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can't use lt1021-5 in 2 wire mode.

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Posted (edited)

I was creating a Mouser parts order to go with the GRLV6 board that was in the recent group buy thread and I was hoping someone could check through it for me. It doesn't have all the terminal blocks etc but I think it has most of what is needed to populate the board. Please let me know if you see something wrong with it.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?State=EDIT&ProjectGUID=093d8820-8d94-4ded-98e3-f79c119a070b

It's missing the voltage reference since I couldn't find the LT1021-10 on Mouser. Would it be fine to substitute this TI voltage reference to make it more complete? http://www.mouser.com/Search/ProductDetail.aspx?R=REF102BPvirtualkey59500000virtualkey595-REF102BP

edit: also, hello everyone it's been a long time

Edited by kpeezy

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The REF102 is series only and you need shunt. I had the same issue and used the lowest noise grade LM4040 instead of just ordering the LT1021 from digikey, but the LT1021 is still better. I just did it out of convenience.

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Posted (edited)

Thanks, I'm going to get the LT1021-10 and just leave that component out of the mouser project list.

Edited by kpeezy

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R7 1.5K, R8 3K, R9 3K, R10 1.5K  will give me 30 Vdc correct?  I assume no other parts need to change.

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Sounds right. What transformer are you using? Also, what voltage tantalums (10uf/47uf)?

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Avel Lindberg Y23 80 VA 30+30 volts.  Is 35 volts ok for the tantalums?  or do I need to go to 50?

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35V would be fine, 25V also. I am looking at a Spice model I got from Kerry which seems to oscillate once you change the gain to something other than the stock 1.5K/1.5K. I'm sure it is something in the model (a device model). I know luvdunhill has one as well, and he told me the same regarding the tantalums (25V sufficient for most outputs).

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ok thanks...

Does anyone have a 30V +/- working?

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I was building a single plus up for 35V out, but not done yet. Spice models are notorious for doing this kind of stuff, particularly when the user is a novice (re: idiot), so I wouldn't worry about anything I said above having any basis in reality. Should work fine.

Is yours for an ssdynahi?

Edited by Pars

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It's for my original 2 channel Dynahi.  The PSU in it has been running since 2007 and Kevin suggested my electrolytics are dying anyway.  I will be building two more for the ss version.  I almost built those first but I felt like finishing the original 2 channel one once and for all.  I re-cased it this past summer

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The schottkys are optional right?   625-SB3H100-E3

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Yes, those are some of the parts I added for myself. Like I said, I added lots of optional parts in that BOM. Just use the original BOM and you'll be fine with changes for R8/R9.

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6 hours ago, sbelyo said:

ok thanks...

Does anyone have a 30V +/- working?

been built several builds,they all working fine 

epQx52I.jpg

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The only instability I would be worried about that isn't proven is lots of capacitance on the output. So, if your are connecting the PSU to a board with say 1000uF rail capacitance - I might start to worry.

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15 hours ago, Pars said:

Yes, those are some of the parts I added for myself. Like I said, I added lots of optional parts in that BOM. Just use the original BOM and you'll be fine with changes for R8/R9.

cool, thanks

1 hour ago, luvdunhill said:

The only instability I would be worried about that isn't proven is lots of capacitance on the output. So, if your are connecting the PSU to a board with say 1000uF rail capacitance - I might start to worry.

I'll check what size caps are on the amp boards

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This would have been real handy when I was making my order yesterday instead of me digging everything up by hand. :lol:

 

Also, somebody mentioned Arrow the other day, and I got about half my parts for cheaper from them including the voltage ref. The free ground shipping helped a lot too in making a split order between them and mouser.

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Sorry man...  I meant to do it earlier but it was too cold in the basement that night.  I'll have to check Arrow out

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I think that luvdunhill and I were mentioning Arrow. I used them for the semis on the GRLV. I just got a 15% off code from them today, valid for the next 5 days
15-GDKP-DS


Sent from my iPhone using Tapatalk

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Most of the semis were the same price for me. Some stuff like the small fets were cheaper but out of stock. Similar situation on a number of CF60's in the right values. I remember I got a better deal on the main power caps, the tantalums, LED's, opamps, sockets and the voltage refs were cheaper than digikey,

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Hmmm.

Built up a GRLV Plus board set for 35Vdc. Testing with a variac at ~20Vac in or so, output is around 20Vdc. However, D1 is not lit, and Q1 Vce is 0V. I've gone thru and checked that I have PNPs/NPNs in the right places, right parts, caps in correctly, etc. Changed out Q1/Q3/Q14, same problem. LED is in right as well. Scratching my head right now.

Q14 Vbe 0.65Vdc

grlv_plus.jpg

 

EDIT: why that would be the opamp locking up Dave...

Raised the voltage on the variac and things snapped right into place. 35.112Vdc out, from what I could measure unshielded on my HP3468, around 48uV of AC noise on output. DC out very stable. 36Vct split bobbin putting out 44Vac unloaded so will need to use a different transformer. Never put it up to line on the transformer, but nothing running hot. Dropping around 14Vdc c-e on the pass transistor at 40Vac input.

Edited by Pars

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