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Oxford Flood Network Sensor build

These are the first draft of the detailed build instructions for the V3 Oxford Flood Network river level sensor. The sensor uses an ultrasonic transceiver measure the distance from the sensor to the water. The changes in the water level are registered as changes in the distance measured. This can then be used to calculate the river depth at that point and over time can be used to track changes in the levels.

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A kit of parts. THis includes the external antenna options and waterproof outdoor sensor. other parts needed are some hookup wire for the temperature sensor. Start by soldering the lowest components first, this is the u.FL connector that is only needed if you are using the external antenna.
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Solder the R1 which is the 4K7, 1/4W resistor used with the temperature sensor. Followed by 100nF capacitors C4 and C5 (I forgot to renumber the parts before manufacture so some numbers appear missing)
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The pair of 10 way header sockets should be soldered next. A tip is to only solder one end then make sure that it is straight and upright before soldering the rest of the pins. If not straight, just touch the soldering iron on the joint to re-align it. It should now look like this with the socket for the Ciseco RFu-328 module.
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To use the external antenna, an additional pin and header must be cut from a spare socket/pin headers. This single pin and header should be fitted together. Insert the Ciseco RFu-328 module then put the header/pin into the PCB so it connects to the antenna pad on the RFu module. Solder the RFu module end first then turn other the PCB to solder the other side. The RFu-328 module can now be removed until assembly has been completed.
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The new antenna connection header socket should look like this now. Another photo of build so far.
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Not a clear photo of the new pin on the RFu-328 module. Continue the build soldering the 2N7000 Mosfet, header strip, FTDI connector, 100uF 10V electrolytic capacitor, temperature sensor connector and battery clips.
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Completed board with RFu-328 fitted. Solder the 7 way right angle header pins to the ultrasonic sensor. It can go in from either side but having it over the label is the way it was done here.
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Mark which end of the header pins is the GND connection as this should mate with the correct end of the The case, its lid and rubber seal.
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The inside of the lid has ribs that will need to be partially removed later to allow the sensor to be mounted properly. Marking the centre of the lid ready for drilling. The lower mark is for the temperature sensor and should be towards the edge so as not to foul the ultrasonic sensor mounting nut.
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A further mark on the side of the box for the external antenna hole. The sensor hole is best made with a 26mm or 27mm hole saw mounted in a pillar drill. I used 27mm as it is what I had available but 26mm would be a better fit.
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Cutting the main hole. Inside the lid.
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Both holes made in the lid. The temperature sensor hole is 6mm. The ribs were removed around the hole using a rotary tool with a cutting disk. Appropriate eye and dust protection should be worn as this can be a messy operation.
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Fit the sensor with the rubber seal on the outside and the O Ring on the inside Fitting the antenna SMA connector. This is a 6mm hole.
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SMA connector fitted. Use the shakeproof washers provided. (?? May need a spot of silicone sealant around it to make it watertight ??) Almost finished.
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Parts to build the temperature sensor probe Solder blue wire to centre pin of DS18B20 temperature sensor and cover with heatshrink tubing then shrink using your preferred method (lighter, heat gun etc). Bend one of the outer pins over to meet the other and snip off a piece of pin.
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Soler the two outer pins together and solder on the brown wire. Use the wider heatshrink tubing to cover all exposed pins and soldered joints.
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Strip 3mm from the other end of the wires, crimp then solder the connections. Insert into the JST plug housing as shown.
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When plugged in, the brown wore goes to and the blue wire to +.  

Still to do:

  • Wiring and mounting Temperature sensor.
  • Alternative antenna options – Integrated and whip antennas
  • Alternative power options – 2AA cells with power pod or Single Tadiran cell
  • Mounting options – Internal magnets for steel bridges, brackets for bolting/screwing.
  • Configuring the sensor node address using the jumper links
  • Publish all the design files – Eagle schematic, PCB layout, Gerbers and Bill of materials.

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