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#221 | |
diyAudio Member
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Quote:
I still need boards. Happy New Year. |
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#222 |
diyAudio Member
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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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dobedobedo... |
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#223 |
diyAudio Donor
diyAudio Member
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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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#224 |
diyAudio Member
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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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#225 |
diyAudio Member
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dobedobedo... |
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#226 |
diyAudio Member
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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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#227 |
diyAudio Member
Join Date: Dec 2003
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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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#228 |
diyAudio Member
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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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#229 |
diyAudio Donor
diyAudio Member
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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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#230 | |
diyAudio Member
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