HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
<<  <  Page 2/2
78RPM
User Rank
Platinum
Re: Fascinating. Can improve accuracy
78RPM   4/18/2014 9:13:24 PM
NO RATINGS
Good idea, armorris. We could use devices using far less current and much lower voltage.  Your comments inspire me to suggest that we could use an FPGA which could draw a couple of nanoamps in sleep mode while providing all the op amps we need and all the peripheral eeprom or SD card data storage we might require when active.  We could store a graph of data over a long time period using very little power.

armorris
User Rank
Platinum
Re: Fascinating. Can improve accuracy
armorris   4/18/2014 4:54:15 PM
The author did a nice machining job on the mechanical parts, and the documentation was good, but as 78RPM pointed out, the circuit relies too heavily on the positive and the negative voltages being exactly the same. As 78RPM mentioned, a "rail splitter" circuit  would solve that problem. Then, you could just run the circuit on one 9 volt battery. A rail splitter would consist of a second opamp and two identical-value resistors. The output of that additional opamp would be a virtual ground. Even if the two resistors (say 10K) are not identical, their ratio would not change and the error could be reliably nulled out.

You could make those resistors 100K and use an MCP607 ultra-low current dual opamp, which draws less than 25uA per opamp, and make a 9 volt battery last a really long time.

78RPM
User Rank
Platinum
Fascinating. Can improve accuracy
78RPM   4/18/2014 3:18:24 PM
NO RATINGS
This is a fascinating project that could be a good science fair experiment measuring the effect on cloud temperature between summer and winter of carbon emissions using long-term readings. One could hook the output to an Arduino or Raspberry Pi and keep a log of readings on an SD card. One could also calibrate an analog panel meter using a custom decal (e.g., DecalPRO) with direct voltage or intensity units.

One problem with using two batteries for positive and negative supplies is that they get imbalanced over time. A better solution would be to use a rail splitter buffer opamp to create a virtual ground exactly half way between positive and negative points.  TI offers a variety of these. The outputs of this, +,-, and VGND provides the supply voltages to your circuit.

<<  <  Page 2/2


Partner Zone
Latest Analysis
Samsung's Galaxy line of smartphones used to fare quite well in the repairability department, but last year's flagship S5 model took a tumble, scoring a meh-inducing 5/10. Will the newly redesigned S6 lead us back into star-studded territory, or will we sink further into the depths of a repairability black hole?
Fifteen European research centers have launched EuroCPS to help European companies develop innovative products for the Internet of Things.
Get your Allman Brothers albums ready. The iconic Volkswagen Microbus may be poised for a comeback, and this time it could be electric.
In 2003, the world contained just over 500 million Internet-connected devices. By 2010, this figure had risen to 12.5 billion connected objects, almost six devices per individual with access to the Internet. Now, as we move into 2015, the number of connected 'things' is expected to reach 25 billion, ultimately edging toward 50 billion by the end of the decade.
NASA engineer Brian Trease studied abroad in Japan as a high school student and used to fold fast-food wrappers into cranes using origami techniques he learned in library books. Inspired by this, he began to imagine that origami could be applied to building spacecraft components, particularly solar panels that could one day send solar power from space to be used on earth.
More:Blogs|News
Design News Webinar Series
3/31/2015 11:00 a.m. California / 2:00 p.m. New York
2/25/2015 11:00 a.m. California / 2:00 p.m. New York
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
5/7/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Apr 20 - 24, Taking the Internet of Things to the Cloud
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Last Archived Class
Sponsored by Proto Labs
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service