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Old 2nd January 2021, 03:53 AM   #221
1883 is offline 1883
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No good, they emailed me with $14.00 per board because of 4 layers
I still need boards.
Happy New Year.
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Old 2nd January 2021, 09:45 AM   #222
myleftear is online now myleftear  Switzerland
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PCBShopper – A Price Comparison Site for Printed Circuit Boards is a price comparator (for pcb-production), recommended by great Mark Johnson...
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Old 2nd January 2021, 06:28 PM   #223
Mark Johnson is offline Mark Johnson  United States
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Here's my invoice from May 2020. I bought 20 boards and paid USD 3.50 per board, including seven day express shipping to California USA. 1 ounce copper, no gold.

I found this PCB fab using the pcbshopper dot com comparison site.


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Old 2nd January 2021, 09:33 PM   #224
1883 is offline 1883
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Default Gerber zip

The file I downloaded this:

Gerber File: TZPTR7_A_VRDN_regulator_rev_A.zip

Not **** A _VRDN_regulator_rev_A_Y50 that you posted.

Where do I get the correct Gerber file?
Thank You.
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Old 2nd January 2021, 10:59 PM   #225
myleftear is online now myleftear  Switzerland
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Where do I get the correct Gerber file?
Post #1, last item?
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Old 3rd January 2021, 03:21 AM   #226
RickRay is online now RickRay  United States
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Since there is very little noise on the output of the VRDN, would it make sense to add a 5volt regulator off the output to provide for a digital power line? Would this mess up the output impedance of the VRDN, does it make sense?
I'm currently using a low noise DC2DC converter to get my +-5Volts I need.
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Old 3rd January 2021, 03:40 AM   #227
Extreme_Boky is offline Extreme_Boky
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This is possible of course, but would you really want to mix the analog and digital grounds via a (common) power supply returns? If it's a DAC you are talking about and its USB stage has an isolated input/ground, then this approach will simply not work because the grounds, once isolated, will be commoned together at the power supply.

However, if you use a SECOND VRDN as pre-regs, purely for a dedicated LT3045 / LT3094 voltage regs (for example), positioned very close to where they are needed...
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Old Yesterday, 04:30 PM   #228
RickRay is online now RickRay  United States
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Has anyone measured what the noise floor is with the VRDN board. I'm not concerned about the board, I'm using it and it is AWESOME. I'm trying to sort out a measuring set-up including an LNA to measure low level noise. I'd like to verify my test set-up.
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Old Yesterday, 04:50 PM   #229
Mark Johnson is offline Mark Johnson  United States
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I haven't calibrated an LNA myself but I have read a few posts on diyAudio over the past few years, written by people who were doing that very thing. They seem to prefer using the Johnson-Nyquist "thermal noise" of a 1% metal film resistor, since this noise is (a) determined by basic physics and not by good/bad circuit design; and also (b) accurately known in advance.

Most of them choose a 1K resistor to do their calibration, which gives a noise voltage density of 4.07 nanovolts per root Hertz, as shown in the Wikipedia article excerpted below.


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Old Yesterday, 05:20 PM   #230
RickRay is online now RickRay  United States
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Quote:
Originally Posted by Mark Johnson View Post
I haven't calibrated an LNA myself but I have read a few posts on diyAudio over the past few years, written by people who were doing that very thing. They seem to prefer using the Johnson-Nyquist "thermal noise" of a 1% metal film resistor, since this noise is (a) determined by basic physics and not by good/bad circuit design; and also (b) accurately known in advance.

Most of them choose a 1K resistor to do their calibration, which gives a noise voltage density of 4.07 nanovolts per root Hertz, as shown in the Wikipedia article excerpted below.


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I will look into the calibration of the LNA. At this point, I'm trying to see if my entire test set-up is in the ball park. I'm feeding the AC from one rail into the LNA, then into and ADC, Focusrite Solo, and using either REW or ARTA to view the RTA. I'm getting a noise floor of about 108dB with both programs. Just wondering if I'm in the ballpark.
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