Nieuw project Hulp nodig?
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fishbeetle
fishbeetle 11 uur geleden
PIC microcontroller code (in XC8) is now complete and fully functional for the prototype hardware. Shut-down timing is computed in real-time based on the state of charge of the supercaps and their rate of voltage drop. The mechanism provides 15 second warning of critical capacitor voltage loss independent of o/p power consumption and size of the super-caps.  A bash shell script running on the Pi (as root) initiates a clean shutdown upon request from PoEUPSPi via a GPIO pin.
Poe UPS Pi
ElektorLabs
ElektorLabs 19 uur geleden
Apparently the A2035H is no longer in production. Maestro has the A2235H, a newer GPS module that does fit on our PCB (although the module is smaller than its predecessor), but it needs two additional 2k2 pull-up resistors from the I2C pins to the 1.8V output of the module. You may also need some (kapton) isolation between the PCB and the module to avoid short circuit between the shielding of the module and a via underneath it.
6-digit Nixie clock [150189]
Volker
Volker 20 uur geleden
Dear Tarsonis, you are correct about the low count rate. We also measured a few counts per minute with the pin-diode based detetctor. The area of the diode is just too small and covers a very small fraction of the 4*pi solid angle. We asked the schools to do a "calibration" with Potassium salt, which is readily available in grocery stores and report their findings, which are stored in some spreadsheet. But they also typically report a few ccounts per minute. The details of the "calibration" are described in the teacher's guide, available from the project web site referenced in the post from April 26. The result of the HPGe detector are encoded on the first map, referenced in my reply from May 1 below. If you click on the respective mushrooms on the map, details about the schools and their send-in samples are displayed on the left. You'll see that the maximum rate (~2000 Bq/kg wet weight of mushrooms) comes from around Sundsvall. My colleagues also prepared a map, where they converted the Bq/kg values to the number of 200g sandwiches with mushrooms you can eat without exceeding any legal limits. Thats shown on the other map from my may-1 post. Here the idea is to provide some gut-feeling to the (typically 8th or 9th grade) pupils what the more abstract Bq/kg readings mean in practice.  
Radiomush, radiology of mushrooms, 30+ years after Tjernobyl
Tarsonis
Tarsonis 1 dag geleden
Hello, thanks replying to me ;) Indeed, I've already read this document, but it is a little but confusing to me; there is no clear Bq/kg value. Also, article says that : "The radiation detector [with BPW pin diode] that the pupils assembled and used in their measurements. " "All mushroom samples have been measured with a HPGe detector, resulting in gamma spectra from which we have determined the activity of 137Cs." The problem is that some HPGe detectors are far more sensitive with low-activity sources than BPW34 PIN diodes. On projects I've built from Elektors/Kainka projects, it is hard to get more that few pulses per minutes, even with radium sources; so far away from detecting hundreds of Bq/kg. So do you know what were values detected by students with Elektor's BPW34 circuits ? Thanks in advance
Radiomush, radiology of mushrooms, 30+ years after Tjernobyl
kyros
kyros 1 dag geleden
Technical Specifications 1. Microcontroller ATmega328 2. 3-AXIS Digital Accelerometer ADXL335 3. Lipo Battery with Charging Board Module 4. 433MHz Wireless Remote Control Transmitter 5. Compact Power Module - voltage input (AC: 90 ~ 264V) the system is based on the ADXL335 accelerometer that has a detection range of ±3 g. It can measure the static acceleration due to gravity , as well as dynamic acceleration resulting from motion, shock, or vibration. A metal ring mounted on the sensor ADXL335 contains perimeter loose steel spheres and magnifies the weak vibrations of the building creating a more intense shock to the sensor the appliance must be plugged in in standby mode in a room outlet the LED will be green (standby mode) Ability to enable / disable device with Power switch the vibration of the building will turn on the device and it will sound alarm the LED will turn red will also activate wireless receivers alarms in other rooms at frequency 433Mhz when the building stops vibrating the audible alarm will stop the LED will turn yellow and the device will return to standby mode the LED will remain yellow (as a memory) reminding that there has been a vibration if we want to restore the entire system to its original state we ,press the reset button  
Earthquake Alarm System