Editing
Talk:DreamTeam/Brainduino
(section)
Jump to navigation
Jump to search
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
==December 14 2016== what is value of c33? 50 pF or 1 nF ? determines high-cut frequency either 160 Hz (1 nF) or 3200 Hz (50 pF) Op amps ... OPA2111 - what gain? expecting ~ 100 ? what values for R27, R23, R24 ? (also R28, R25, R26) R27 should be 2K ohms R23, R24 -> 100K ohms cf instrumentation amp (figure 9 of http://www.ti.com/lit/ds/symlink/opa2111.pdf) 1 + (R23 + R24) / R27 ... so 1 + (200 K / 2 K) = 101 so if input signal is on order of 100 microvolts then output of first amp will be 10.100 millivolts (really more like -50 to +50 microvolts -> -5 to +5 millivolts) AD8422 R5 and R6 are 200 ohms G = 1 + (19.8 kΩ/RG) = 1 + 99 = 100 ??? also see fig. 56 on page 20 of http://www.analog.com/media/en/technical-documentation/data-sheets/AD8422.pdf now consider if input to AD8422 is on order of 10 millivolts output will be 1.000 volts (or if no offset voltage and input is actually ~ -5 to +5 millivolts, then output will be -0.5 to +0.5 volts) (however, there is a +2.5 Volt DC offset impinging on the AD2177 part of the instrumentation amp setup ... we think this is ok to say ... But is option A grounded -- no offset -- or 2.5 volts ? where might DC offset voltage come into play? 2nd Stage AD8422 Instrumentation amp with gain resistor 2(10 kΩ + RREF)/(20 kΩ + RREF) http://www.analog.com/media/en/technical-documentation/data-sheets/AD8422.pdf In figure 56, you will see that an op amp is used to input to the VREF pin. 3rd stage Low-cut (aka high-pass ) filter and DC offset to 3rd Stage OP2177ARMZ ( IC1B Ch1 and IC1A Ch2 ) 4th Stage IC3D>IC3C Ch1, and IC3A>IC3B, Potentially considered a two-pole high-cut(aka low-pass) Next week: verify 101 x gain, 100 x gain, DC offset !
Summary:
Please note that all contributions to Noisebridge are considered to be released under the Creative Commons Attribution-NonCommercial-ShareAlike (see
Noisebridge:Copyrights
for details). If you do not want your writing to be edited mercilessly and redistributed at will, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource.
Do not submit copyrighted work without permission!
To protect the wiki against automated edit spam, we kindly ask you to solve the following CAPTCHA:
Cancel
Editing help
(opens in new window)
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Log in
Request account
Namespaces
Page
Discussion
English
Views
Read
Edit
Add topic
View history
More
Search
Dig in!
Noisebridge
- Status: MOVED
- Donate
- ABOUT
- Accessibility
- Vision
- Blog
Manual
MANUAL
Visitors
Participation
Community Standards
Channels
Operations
Events
EVENTS
Guilds
GUILDS
- Meta
- Electronics
- Fabrication
- Games
- Music
- Library
- Neuro
- Philosophy
- Funding
- Art
- Crypto
- Documentation/Wiki
Wiki
Recent Changes
Random Page
Help
Categories
(Edit)
Tools
What links here
Related changes
Special pages
Page information