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  • RE: Rodeostat FeatherWing

    The Rodeostat FeatherWing does use slightly lower cost components than the Rodoestat in order to keep costs down. However, overall the accuracy of the Rodeostat FeatherWing is fairly comparable to the Rodeostat. The main differences are as follows.

    The Rodeostat FeatherWing has a more limited fixed voltage output range (+/- 1.65V) whereas the Rodeostat has a four voltage ranges which can selected via software(+/- 1, 2, 5, 10V).

    The Rodeostat FeatherWing comes in a single fixed current range, which is specified at time of purchase, whereas the current range for the Rodeostat can be selected via software (+/- 1, 10, 100, 1000) .

    Finally, the Rodeostat is a complete USB instrument which comes preprogrammed with firmware and can be controlled from the host PC using our python library or with Webapp software. In contrast the Rodeostat FeatherWing is designed to be used as an expansion board and only works when connected to a Feather development board, such as Adafruit's Feather M4 Express, PyBadge or PyGamer. You need to write your own firmware for controlling the Rodestat FeatherWing on the Feather development board.

    posted in Rodeostat
  • RE: Which analog section of the rodeostat that is performing the chronoamperometry

    There isn't a special section of the Rodeostat hardware which is specific to chronoamperometry vs some other test such as like say cyclic voltammetry as the same hardware is exactly the same for all tests. The tests are implemented in firmware on the teensy 3.2..

    posted in Rodeostat
  • RE: How to set curr_range to more than 1000uA?


    With the default hardware and hardware there are four current ranges +/- 1, 10, 100 and 1000 uA. So +/-1000uA is the maximum allowed current range. It is possible to change this but it requires a hardware modification and firmware modification. You won't be able to set higher than 1000uA without these changes. You would need to make these modifications yourself. There are some forum notes on increasing the current range here The firmware modifications can be enabled by uncommenting the the #define CURRENT_VARIANT_MILL_AMP and commenting the #define CURRENT_VARIANT_MICRO_AMP in the ps_hardware_variant_defs.h file You then need to reflash the firmware.

    posted in Rodeostat
  • RE: How to run different experiments on different channels using Multichannel Potentiostat


    It is not possible to run multiple experiments, such as constant and cyclic voltammetry, simultaneously with the multiplexed version of the Rodeostat. You can use up to 7 working electrodes, but you still only have 1 reference and 1 counter electrode. So the time course of the potential between the all of the working electrodes and the reference electrode will be the same during a test.

    posted in Rodeostat
  • RE: How to run SquareWave tests with Multichannel Potentiostat


    This is not currently possible with the current firmware to do the SquareWave test with the multiplexer. Enabling this will require some fairly extensive modifications to the device firmware.

    posted in Rodeostat
  • RE: troubleshooting new colorimeter


    You might try testing to see if the there is an issue with either the LED or the sensor board.

    First test the LED. Open up slider on top of the colorimeter and ensure that the sensor is exposed to light - ambient room light should be fine. Make sure there is light hitting the sensor. With the top open and light hitting the sensor start the colorimeter-basic program and try running the "Calibrate" routine. You should see the LED flash red, green, blue ,white in sequence. Note, you can increase the duration which each LED color is on by increasing the number of samples - say from 500 to 5000. If the LEDs are flashing all four colors in sequence then they are working.

    Next check to see if the sensor board is working. Again to do this again you will want to expose the colorimeter sensor to ambient light. In this case it might be easier to unscrew the top of the colorimeter and pull out the sensor board. It should be connected to the Arduino by the gray ribbon cable. It doesn't need to connected to the LED by the 4-connector cable for this test. Expose the sensor to room light and run "Calibrate" in the colorimete-basic program. Then partially obstruct the light hitting the sensor with your hand or a piece of paper and run the "Measure" routine. As less light is hitting the sensor you should see nonzero absorbance values for all color channels.

    posted in Colorimeter
  • RE: Measuring CV currents around +- 10nA


    I think the +/-1uA is probably pushing it. I think you would probably want something more like a +/-50 or 100nA range. It is possible to modify the Rodeostat to reduce the current range. We have made modified versions with +/-60nA and +/-100nA ragnes. There are some notes on how to do this in the "hardware/pcbs/teensy_shield/notes" sub-directory of the project repository See the file named "nano_amp_mods.txt". We made two versions the 2nd worked best. The changes were as follows:

    1. R5 = 6.04 MOhm, C19 = 10nF capacitor (100nF range)
      Digikey PN: 541-6.04MCCT-ND, and 311-1136-1-ND

    2. R6 = 10 MOhm, C20 = 100nF (60nF range)
      Digikey PN: 541-10MAZCT-ND and Digikey 311-1361-1-ND

    There is modified firmware available for these ranges you just need to enable the CURRENT_VARIANT_NANO_AMP #define in the in ps_hardware_variant_defs.h and comment out the CURRENT_VARIANT_MICRO_AMP #define. The ps_hardware_variant_defs.h is found in the firmware/libraries/potentiostat/ sub-directory.

    posted in Rodeostat
  • RE: OpenSource software recommendation?


    I think darktable would be a reasonable option

    You can find a list of supported cameras here

    There is some information of camera tethering here

    posted in Electrophoresis and Gel Imaging
  • RE: Problems with serialport AppImage on Linux (Rasperry Pi 3)


    The current AppImage binary is built for x86-64 whereas the rpi is ARM. So in order to get this to work you will need to rebuild the serialport-bridge AppImage from source for ARM. This can be done on the raspberry pi itself. The source code for the serialport-bridge can be found here You should be able to rebuild the package using "npm build". I have tried this, but I think it should work.

    posted in Announcements
  • RE: Bluetooth


    I've been working on firmware examples for the new featherwing. Right now all of the examples use circuitpython. I haven't put in an online repository yet. I will do this in over the next few days. I've been pretty pleased with how well circuitpython has worked for this - very easy and quick to program.

    Right now all of the firmware examples just stream the data back to the host PC over USB. I am also pretty excited about trying to make some standalone devices which use feathers such as the pygamer which have a display, battery connection/charging, SD card, etc. The rodeostat featherwing can be plugged directly into the connector on back. It seems super nice for making a battery powered portable device. The pybadge is also interesting I think both are still available from Digikey.

    We should have the featherwing PCBs available in about two or three weeks. There is some uncertainty on when we will receive the PCBs ... not surprisingly.

    posted in Rodeostat