Project Logs

Collapse

• Open Source rules!

  Radu Motisan • 08/05/2017 at 21:54 • 0 comments

  Hi just finished fixing a list of about 15 issues on github. This resulted in a new firmware version update and a new hardware iteration - minor with just a few values of some resistors changed. One of these was particularly interesting.

  As discussed with @Ted Huntington via the comments the other day, the high voltage inverter in these units jumps from 3.3V input to a configurable output voltage that is now set to 380V to fit the SBM-20 Geiger tube. To achieve this long jump, some components are critical to the design, such as the MPSA42 transistor and the 2.2mH inductor. For the latter, some of those building this circuit were having some issues, not being able to obtain the target voltage, or in some cases needing to change (lower) the inductor frequency to get the last push to the target. I did my best to indicate the right sources for the inductors, but in some cases this was not enough.

  So what happened with the github issues? Well Wolferl1 pointed out some issues with the values I've been using. And indeed, he was right. I changed those right away, and this brought some immediate improvements, such as lower PWM duty cycle to the high voltage inverter, and lower power consumption:

  But the lower duty cycle gives more margin to the inductor working interval, lowering the criticality of this component. His suggestions went further like using a 47M resistor in the high voltage divider circuit used for feedback, but I decided to go with more common components.

  Yet, another example of team work, making this product better. Open source rules!

• Going for CE-rtifications

  Radu Motisan • 08/05/2017 at 11:12 • 0 comments

  This project addresses mostly DIY enthusiasts and IOT fans, however I felt it reached a point where it is mature. That's because it got everything one HW product could possible want: multiple iterations, community support, community new features and new code and a high number of units distributed across the globe.

  It was time to add one missing thing to complete the work and that is certifications. First I wanted was CE, offering extra trust to what this product is. So I started researching ways of accomplishing the CE tests with minimum costs. I was able to identify a company, discussions went well, I send them the payment and the documentation and things started to move.

  What they did was a large number of tests to verify literally everything, from drop tests to EM interferences.

  In the end I got the "TEST PASS" label, together with hundreds of pages of reports, documenting every technical aspect of the device and of the test, probably more then I knew about the device I designed. The company I used was BCTC in Shenzhen, and I am very happy with their professionalism and promptitude.

  Mission accomplished.

• KIT1 iterations

  Radu Motisan • 05/11/2017 at 16:33 • 4 comments

  Developing the KIT1 raised several problems in hardware and software, and those were solved with multiple PCB iterations.

  These are just of the few that were built. Initially, v1.0 used a ferrite transformer for the High Voltage inverter needed to boost the 3V Vcc up to 400V required by the Geiger tube. Making such a transformer was a difficult task, that would limit the production capabilities. The secondary needed about 400 turns of very thin wire:

  This was the most important change in the 1.1 versions, replacing the ferrite transformer with a simple inductor readily available in electronics shops. A voltage multiplier would compensate for the lower voltage of the new inverter, so we would still reach the 400V target needed by the Geiger tube. The switching transistor is blocked with a second PNP transistor to collapse the magnetic field on the coil faster, and generate higher voltage spikes. More on the development of a compact high voltage inverter here. This approach was used in the uRADMonitor model A as well, just with SMD components.

  Version 1.1.103 is not visible in the first picture, but you can see it below. 103 was supplied after the successful indieGogo campaign in 2016, both as a solderable KITs and a readily assembled units.

  1.1.104 brings an extension port, used to connect additional sensors. The Repository on GITHUB offers default code with a driver for the Bosch BME280 sensor included by default.

  1.2.105 is a new kind of beast. The board has been reworked, the speaker and central button were moved, the PCB under the tube has a milling layer to avoid any interferences on the radiation detection capabilities, and the ISP connector went from the redundant 10pin variant to the 6pin standard.

  The extension port outputs voltage, I2C and UART connections to the microcontroller. You can use it for virtually any kind of sensor using these protocols, like PM2.5 sensors, UV sensors and so on.

  The GitHUB code comes with a dynamic ID allocation system, that means the units can join the uradmonitor network automatically.

  Community variants

  I already presented the advantages of the community support for this open source design in the previous logs. The KIT1 development took advantage of the creative effort of many makers out there.

  Here are some pictures showing a few of them:

  Chris and Frederik built a SMD variant, with a LIPO adapter to make the KIT1 fully portable. They also did a 3D printable enclosure:

  Otakar built his from scratch, using version 1.1.103 design files:

  Tino, did an amazing job building 3 units from scratch:

  Adrian used the excellent @oshpark services for his KIT1 unit which came out nicely:

  Here's an interesting, highly customised KIT1 version:

  Here's Horia and Fabio, good friends from the 4HV.org forum, with their fresh new KIT1, ready to take some of Fabio's X-RAY experiments:

  Malte built the new 1.2.105 on a beautiful orange PCB. Need to ask him where did he order it from. He also use a big fat inductor, that really can't go unnoticed:

  Here's another one from Nicolas, including a custom enclosure:

  Some simulations of the circuit and firmware some other guys were doing:

  Sulley's unit running on 2 AA batteries (like originally planned):

  And the masterpiece created by Akos, that you saw in one of the previous project logs:

  Here's another KIT1 built from scratch, most likely using toner transfer:

  Hori's LiPO solution:

  One beautiful 3D Printable enclosure, available on Thingiverse:

  @Kumar, Abhishek's unit, still hoping he will connect it to the Internet someday:

  And who said the KIT1 can't talk wireless? The design is made for the ENC28J60, but this clever maker found a solution to connect to it's wireless router via the waves:

  
  

  Tempted to build yours? I surely hope so! The latest design is available on Github. It will only take you a few hours to do a toner transfer PCB and have some fun soldering this versatile IOT device:

  You'll find the complete code there as well, or you can use this direct link. More information is available on...

  Read more »

• Open Source uRADMonitor KIT1

  Radu Motisan • 05/11/2017 at 15:05 • 0 comments

  Open Source means collaborative work, joined effort leading to extraordinary things. Recently we saw how a talented maker from Oradea, Romaniapushed his KIT1 #uradmonitor unit to the limit!
  
  He used a lot of his personal time to build and document something better than the original. In the end he asked for nothing except to get access to the entire KIT1 source code so it can be improved further by the community of makers. We got the message and decided to act.

  The server infrastructure

  uRADMonitor is Big Data. Hundreds of detectors worldwide are collecting measurements every minute, and the server deals with millions of entries in its database every day. The database holding KIT1 data was designed for efficiency: only the minimum data goes in. One reason for open sourcing was to allow customising the KIT1 units with additional sensors. We had to adapt the server backend in this regards, and now there’s an expandable list of parameters that can be uploaded.
  Then there’s the data accuracy which needs to be guaranteed to a reasonable degree by supervising and testing the hardware, something impossible with open, remote constructions. Making the server decide if the data is genuine or just some random useless bits was not an easy task.
  Last but not least, here comes the security. Initially, open source can be a source of vulnerabilities of the exposed system. We had to make sure the new open communication protocol is safe to use. We’ve implemented API Authorisation for all data uploads generated by the Open Source KIT1 units. Go to the dashboard, and create an account if you don’t have one already. You’ll need to use the user-id and the user-key listed there with your new uRADMonitor KIT1. If you go for the stock firmware, then you won’t need them.

  Please welcome the Open Source uRADMonitor KIT1

  With so many changes on the server backend, we had to improve the KIT1 circuit and PCB. We tried to add many of the suggestions received on the forum. From now on however, feel free to fork the original Github repository and do whatever you like with this open design. The new version is KIT1.2.105, and you can see the first design images below:
  
  
  The new design is more compact, so if you want to add a battery you’ll have more space. The arrangement of some components has been optimised and the regulator becomes the single SMD component on this otherwise exclusively through hole components PCB. As soon as we get the first of the new PCBs, we’ll add more pictures with them.

  Using the KIT1.2

  Once your KIT1.2 circuit is complete, download the firmware code from Github. In config.h add your user-id and user-key from the dashboard.
  
  Compile the code, and write the HEX to your board, using a 6 PIN ISP connector. For the fuse settings, if you followed the original design, you’ll need to set the external 8MHz crystal, and make sure the EESAVE fusebit is set.

  avrdude -p atmega328p -c usbasp -U lfuse:w:0xDC:m -U hfuse:w:0xD7:m  
  avrdude -p atmega328p -c usbasp -U flash:w:uradmonitor-KIT1-EXP.hex:i

  Your unit will receive a device ID allocated dynamically by the server. If you want to use a BME280 sensor, there is code already in place. Just make sure the USE_BME280_SENSOR is set in the config file.

  Adding more sensors

  With the extension port that exposes I2C, UART and power, you have the possibility to add a large number of additional sensors. Add the sensor driver code, and do the sensor reading in app/data.cpp and app/data.h initSensors() and readSensorsSlow(). To send the data online, see the code file misc/expProtocol.h for parameter IDs and how they are used in uRADMonitor.cpp line 350. More parameter IDs will be added based on demand. All previous KIT1 hardware versions are compatible with the new firmware. For any questions and assistance, use the forum.
  To compile the code, please use Eclipse and the AVR Crosspack plugin as well as the AVRDude software. For uploading the HEX code, you can use the versatile usbAsp programmer configured for 3.3V!

  License

  uRADMonitor...

  Read more »

• Building the KIT1 with extra features

  Radu Motisan • 05/11/2017 at 15:04 • 0 comments

  As the KIT1 is open source, talented community makers often brought upgrades to this versatile IOT platform. Here' the work of Akos, that adapted the KIT for battery use and also built a plexiglass enclosure.

  Last week I’ve assembled a KIT1 and posted some details about it to the forum. radhoo praised the article and asked me to share it on this blog, maybe will be helpful for the readers. So, here is an updated “copy-paste” from the original post.
  The diy kit is based on the v1.1.104 pcb. It was made with minor modifications / improvements regarding the original model. First of all, I’m a beginner in all this electronics and coding stuff, so if I wrote something stupid, please correct me. I’m always open for constructive criticism. Second, sorry for my English, it is not my native language.

  Differences to the original KIT1

  – Incorporated lithium battery
  – Builtin battery charger module + micro usb port
  – Low dropout (0.17v) regulator
  – Real PoE connectivity, no additional cable / connector needed on the device side, just the rj45 connector
  – Transparent case made from plexiglass
  Updated BOM, with the components I used (if something is missing, please let me know).
  Note: I bought the components for these kits from local stores, the best available quality. Hence, the visual aspect of these components may differ from the originals shipped with the KIT1. I measured / tested all of them before soldering, to make sure everything is up to the specs.
  
  I built 2 kits: one for me and on for a friend. He asked to make it portable, because he will use it mainly on field, as a mobile unit, outdoors and on industrial working sites. This raised two challenges:
  The final product has to have a:
  – reliable and high capacity rechargeable battery
  – a robust but not too bulky case
  Regarding the pcbs, after some emails, radhoo was so kind to send me 2 pieces, thank you again! And because i didn’t want to ‘destroy’ these beauties, all the modifications are made without hacking the pcb!

  Power supply / charger / power consumption

  Nowadays the “standard” power supply for handheld devices is the type b micro usb port. You can find them virtually anywhere. Also, it is fairly easy (and very cheap) to implement them into DIY stuff, using these modules. To add these without modifying the pcb, I simply glued them with 10 minutes epoxy. Not too smart, but will surely withstand the abuse of the backlash from the usb cable.
  As for the battery, probably everybody has access to some broken smartphones… although the phone or display is broken, chances are good that the battery is still functional. You just have to hook up to the output of the charging module and the input of the voltage stabiliser and it is ready to use. I’ve used one scavenged element from an old macbook battery. It contains 4 lithium cells, similar to the one on this site. The cells are roughly the size of the kit1 pcb. This way, I saved all costs on charger + battery (0.3 euro).
  To keep a safe distance between the aluminum foil of the battery and the bottom of the pcb (high voltage!), I used 4 self adhesive rubber shoes, like those intended for furniture.
  Most lithium batteries have a nominal voltage of 3.6V (min 2.9V, max 4.2V). The recommended operating voltage for the KIT1 is min 3.0V, max 3.3V. To use the battery to the maximum, I opted for a 3.0V voltage regulator. It has to have ultra low dropout voltage, in order to maximize battery life.
  I also had to replace the original lm1117 voltage stabiliser, because it has a large dropout voltage, 1.1v. (this would be: 3.0 + 1.1 = 4.1v, maybe just 5% of the overall battery capacity. Not suited for my case … ).
  After a lot of research, I bought the MCP1700-3002E/TO regulator. It has a very low dropout, only 0.17V! We get: 3.0 + 0.17 = 3.17v, so I can use around 95% battery capacity. So far, so good.
  The max output current for the MCP1700 is 250mA, and the max input voltage is 6.0V. As the lithium battery never goes above 4.2v, it’s ok for me....

  Read more »

• getting the KIT on HaD

  Radu Motisan • 10/04/2015 at 18:11 • 0 comments

  This is probably the easiest way one can take to have a good digital radiation dosimeters. It was built for the SBM20 Geiger tube, widely available at reasonable prices. Alternatively, other tubes can be used and the PCB has been designed to fit various tubes. The high voltage inverter can also go as high as 600V, to accommodate any custom tubes. The version currently posted on HaD is the latest, the KIT 1.1 and brings several improvements as presented in the project description.

  KIT1.0:

  KIT1.1:

  The best thing about this update is the high voltage inverter update, that now uses a choke instead of the custom ferrite core transformer. So all this can be built in just a couple of minutes with readily available components, for a low cost.

  The software has been updated as well, having nice improvements in place like timeout for the LCD backlight or UI split into pages, to show all the relevant details and measurements grouped together. Just press the main button to navigate through them.

View all 6 project logs