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Old 16th March 2013, 02:37 PM   #11
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Grufti,

yah I know about the + one -- in order to test NOT using the ES9023 charge-pump we'd need also a NEG one, so is there a mirror to the 5205 3.6v in "negative"?
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Old 16th March 2013, 03:10 PM   #12
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The voltage at the NEG pin is -3.4V {like it was at the Vreg pin}, this with a +3.6V source to the DAC. Now it may be that someone else will get different figure; I have 100K to ground on Vreg. pin#6
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Old 16th March 2013, 05:19 PM   #13
grufti is offline grufti  United States
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The Linear Technology LT3032 Series - Dual 150mA Positive/Negative Low Noise Low Dropout Linear Regulator comes in a adjustable version. It should probably be set to -3.3V / -3.4V rather than -3.6V because that seems to be what the charge pump generates.

Digikey # LT3032IDE#PBF-ND


The LT3032 package is not exactly easy to solder, but there is also the LT 1964.

The Linear Technology LT1964 is available in a more convenient package, adjustable and significantly cheaper. It is marginally noisier, but possibly still "better" than the internally generated negative supply.

Digikey # LT1964ES5-BYP#TRMPBFCT-ND

I hope this helps.
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Old 16th March 2013, 06:43 PM   #14
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Helps a LOT! First to experiment with whatever I have or will get fast. Now remember the NEG 3.4 was with 100K to ground off ES9023 PIN#6, which not many people would do. [Heavily modded HiFIMEDIY UAE23]

A regulator that is POS AND NEG in one package -- hey whata find! If this works we might come up with a way to "NUL" the DAC or offset...tune V balance around 0...hopefully not see DC at the outs, or, not much. Just thinking aloud, who knows it will work at all?

C9 on the beta board, I think polarity may need reversing? Or use Non-polar C? that is ES9023 "NEG".
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Old 16th March 2013, 07:34 PM   #15
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Quote:
Originally Posted by enjoybiking View Post
C9 on the beta board, I think polarity may need reversing? Or use Non-polar C? that is ES9023 "NEG".
Polarity of C9 is indeed reversed . Already mentioned it to some, but not all. So thats a good remark. Thanks

I am out for about one week since we are currently refurbishing some rooms. My lab will be quite nice soon

Btw.: Mic5205 is pin compatible with LT1761 but the bypass C needs to connect BYP to GND while its between BYP and OUT for the LT1761.

I am looking forward to the test results regarding "disabled" charge pump and external NEG supply. Downside would be the board layout with the dual supply which would probably be worse with respect to proper ground layout

Best regards, Daniel
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Old 16th March 2013, 08:52 PM   #16
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NEG is just one of those questions. I may just tack a -5 regulator on my +/- 15V regulator board and fly the wire over {from loaded -voltage divider, maybe a 100R POT set mid-range?} and tack a non-polar SMD cap on the NEG pin to ground. {and somewhere a sense wire for my meter}. This weekend is no good for me though; I have other obligations.

a NEGATIVE supply could come from PCB edge: 3 terminal screw lug instead of 2. Frankly, one other option is +/- 15 and +/- 5 on another PSU board or down one side of the existing art? The FAB we used? I'm pretty sure THEY do not slot or drill for break-away. {I know one that WILL} Existing board is 6x7CM and FAB charges same rate as 10x10. I KNOW that would be a lot of work. I am NOT arm-twisting. TO220 regulators get pretty cheap {NJM7915FA example USD $0.64Ea. 100+ 170uV noise, insulated TAB}, fast low-Vf diodes... a nul-adj with safety R? {for -3.??V}. or "balance" a +/- combo regulator? I can do it on perf-board too.

The next wave of LT1761 3.3V {for OSCILLATORs} arrived, I have 825x on hand.
I have a bag of Micrel 5205 3.6, but not enough for all beta boards.

I have To-92 -5 regulators and some multi-turn POTS coming for a NEG-pin test. I guess that means I have to dig out my scope. I HAVE NJM7905FA regulators here.
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Old 19th March 2013, 06:32 AM   #17
diyskat is offline diyskat  Australia
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I've just measured the NEG (pin#11) pin on my unmodded UAE23 at 25C and it shows -3.4V idle and 3.39V at max volume with 160Ohm headphones plugged in directly. The VREG pin shows 1.31V. I did this measurement to add to enjoybiking's one as I expected the AVCC (pin#5) to be 3.3V but it seems like the unmodified UAE23 v1.2 actually uses an adjustable LT1763 and feeds 3.6V. My version, unlike enjoybiking's one, does not have the 100+K on pin #6 to ground yet.
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Old 19th March 2013, 02:45 PM   #18
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That's FUNNY!! So if only one regulator, they are running the TE7022 at 3.6? Well, everything on the board. That star shaped intersection at center of board on back is at 3.6 then? Was the Vreg reading negative or +? Man I must be losing it? I'll retake the VREG reading soon, everything is put away for company *<:~) The NEG reading makes sense, that's good. I will not have any bench time for a bit yet -- at which time I will mock up the supplies... I have 36Vct transformers and +/- 15 boards... I can hang a -5 REG off that and try say a 100 ohm POT from that to ground [preset to mid range], tune it for -3.4 unloaded then apply to es9023 NEG. See if it varies. I will probably have a cap at the POT wiper too, nothing big.
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Old 20th March 2013, 06:09 AM   #19
diyskat is offline diyskat  Australia
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The Vreg pin measured positive 1.31V.
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Old 24th March 2013, 09:38 PM   #20
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100 of each FET graded and taped to paper each with specs -- that took a while! 3hrs with a few small breaks. I can take care of the 2x USA Beta guys now!! One is prepaid, the other {S} we'll calculate your order now and ship.
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