I meant for you to subtract the signal from a positive voltage.
It's a 30Hz square wave sitting on top of about 8 volts driven by photocurrent from thermal IR. I need to be able to dynamically adjust against that background.
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Verdris's ContentThere have been 20 items by Verdris (Search limited from 07-May 23) #50779 Building a "valley detector"Posted by Verdris on 24 June 2013 - 11:25 PM in General Discussion
It's a 30Hz square wave sitting on top of about 8 volts driven by photocurrent from thermal IR. I need to be able to dynamically adjust against that background. #50782 Building a "valley detector"Posted by Verdris on 25 June 2013 - 12:00 AM in General Discussion
And amplify the difference. The big picture is to dynamically remove the background, as it's not a constant 8V, but varies from 0-10V. #50800 Building a "valley detector"Posted by Verdris on 25 June 2013 - 04:14 PM in General Discussion
Currently, the idea is to extract the background with LabView and feed it via analog output to a differential amplifier. It's not strictly available on its own, since the entire signal comes from a single sensor. #50846 Building a "valley detector"Posted by Verdris on 26 June 2013 - 07:41 PM in General Discussion
Might give this a try. Thanks!
Edit: gave it a try. It worked, but not as well as our current filtering idea which is the LabView-provided minimum for the differential amp. #50770 Building a "valley detector"Posted by Verdris on 24 June 2013 - 09:24 PM in General Discussion [color=rgb(102,102,102);font-family:'Lucida Grande', Lucida, Verdana, sans-serif;font-size:13px;background-color:rgb(245,245,245);]Does anyone know a good op-amp implementation of a "Valley Detector", which I assume would be what one calls the opposite of a peak detector? I need to find the baseline of a signal so I can reject it. I want to do an op-amp circuit instead of with a DAQ so I can do it in real time.[/color] #50774 Building a "valley detector"Posted by Verdris on 24 June 2013 - 10:42 PM in General Discussion
I could be wrong, but I think Inversion is not a valid technique here since all signals are nonzero and positive. This isn't an AC signal. #50303 System.ArgumentException when using GPIO Pin 9Posted by Verdris on 05 June 2013 - 06:08 PM in Netduino Plus 2 (and Netduino Plus 1) From the schematics, it looks like pin 9 is also shared by the SPI bus that the Ethernet encoder sits on. Maybe that's why it's not so happy being declared as an interrupt? #50554 OT: Why no Long Jumper Wires?Posted by Verdris on 17 June 2013 - 03:33 PM in General Discussion Long wires are basically antennae for mains frequency noise. Also, they're great inductive reactance devices and breadboarding makes every connection good candidates for memristors, which screw up the inductive properties of your circuit. That's just the inherent problem with breadboarding. Whenever possible, use short wires and small circuits. #53475 VS2013 support?Posted by Verdris on 23 October 2013 - 06:46 PM in Visual Studio On October 31, VS2013 will be released. It's currently out as an RC, and I'm downloading/installing it now.
Is there any news on VS2013 support for the Netduino? #50333 Dear Trolls/Anti-AgentsPosted by Verdris on 06 June 2013 - 10:27 PM in General Discussion
Maybe they can throw some funding towards developing a mini powered by the STM32F! #50223 IC or transistor to act as relay switchPosted by Verdris on 03 June 2013 - 07:06 PM in General Discussion
Couldn't you hard reset your PC by holding the power button until it turns off, waiting 10 seconds, then turning it on again? Or do you need to automate this? #50302 Power supply specifies minimum output voltage?Posted by Verdris on 05 June 2013 - 05:56 PM in General Discussion I've got a Rosewill PS and the datasheet specifies that the 3.3V bus has a minimum output current of 1A. I've never seen a minimum current output specified before. Does this mean that the PS will push a minimum of 1A, regardless of the current needed by the load? #58291 For slow digital circuits, do I need ground between each wire?Posted by Verdris on 20 May 2014 - 06:06 PM in General Discussion I'm designing a pass-through circuit for a project at work, and I'm running in to space issues. I have a block of thirteen digital signals and I'm wondering if I need a ground wire between each. The ribbon from my circuit to the next board is maybe 6 inches, and the signals are 0-5V logic that change states maybe once per minute. Seriously slow. #58325 For slow digital circuits, do I need ground between each wire?Posted by Verdris on 21 May 2014 - 03:13 PM in General Discussion
Thanks for the reply. The grounds aren't carrying power, they're strictly logic reference. I've got many other power grounds. #51315 Thinking Of Begining To Use NetduinoPosted by Verdris on 10 July 2013 - 07:32 PM in General Discussion It sounds like a Raspberry Pi would be more suitable. #51314 Air quality sensorPosted by Verdris on 10 July 2013 - 07:20 PM in General Discussion I'd do two identical water temperature sensors, one in the tank and one somehow in the bowl. If the readings differ significantly for a while after someone has left the bathroom, they probably didn't flush. #50673 VinPosted by Verdris on 20 June 2013 - 09:08 PM in Netduino Plus 2 (and Netduino Plus 1) It's the same as the barrel jack. You can use either for unregulated 7.5-9v input power. Both go to the regulators that power the board. #50676 Mocking Inputs?Posted by Verdris on 20 June 2013 - 10:22 PM in General Discussion I, too, would be interested in this. #50558 Alternative to NFC tags?Posted by Verdris on 17 June 2013 - 03:37 PM in General Discussion Hi all,
I had a fun idea that would add a little flair to a project I'm working on. I do instrument development for a climate research group and I'm building a networked array of instruments (using Netduino!) that communicate with various wireless protocols (WiFi, cellular networks, etc). That's easy enough, but what I want to do is write an android app to allow our field engineers to be able to use NFC communication to receive real-time data from the instruments to their phones and tablets. Previously I was just using QR codes to let the engineers connect to the webserver and automatically navigate to the relevant instrument's page, but in the case of a network failure I want the instruments to still be serviceable.
I like the idea of NFC, but I can't output data over an NFC tag without an NFC programmer of some sort. I found this:
http://www.nxp.com/d...N532_C1_SDS.pdf
I'm wondering if anyone has enough information on NFC to tell me if I can use Netduino to interface with this to produce a constant stream of NFC data that I can recover with a smartphone.
Or would Bluetooth be better? #50848 Has anyone used/have code for SHT21 Humidity Sensor?Posted by Verdris on 26 June 2013 - 08:16 PM in Netduino Plus 2 (and Netduino Plus 1) Programming this to work with the Netduino will probably take you less time than waiting for someone else's code. I've used SHT21s before and they're incredibly simple. However, don't query them more than once per second as they're prone to self-heating.
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