Sensor construction manual - Alkaline battery pack version

Tools Needed

• Saw to cut PVC pipe (A chop saw or equivalent work best on 3” PVC)
• Ratcheting PVC cutter for ½” PVC
• Drill
• 1/8” bit for float switch wires
• X-acto knife or similar
• Measuring tool
• Soldering iron
• Heat shrink wire wrapping
• DuPont connector crimper
• Allen wrench set

Supplies Needed

• PVC pipe primer and glue
• Two-part epoxy (if using float switch)
• Headers for OLA and Bluetooth module
• Dupont connector crimp ends
• Dupont connector shrouds
• M3 x 6mm Hex head machine screws – used to screw the OLA into carrier (NOTE: M3’s don’t fit into Adafruit BLE board, so we may want to standardize on m2.5. That could require a modification to the electronics carrier part so that the holes are still self-tapping.)
• M2.5 x approx. 10mm to mound BLE board
• If using float switch, 2 8-32 x 1” Stainless steel machine screws and nylock nuts
• Battery packs
• Desiccant packs
• Foam padding

Sensor Housing

End cap penetration - ONLY if using float switch

If not using float switch substitute a “Quik cap” rubber end cap.

• Drill two 1/8” holes in center of PVC cap for float switch wires. If the wires don’t fit through the hole drilled into the PVC pipe because of the solder blob, you can melt it down using the soldering rod.
• Tie wires into knots so they won’t go anywhere while the epoxy is setting, you can use electrical tape to keep them together if you need to.

• Fill inside of cap with epoxy around float switch wires taking care not to get any epoxy on sides of cap.

PVC Housing

Cut PVC pipe pieces in the following lengths:

• 2” PVC (battery side of tee): 7"
• 2” PVC (electronics side of tee): 3”
• ½” PVC (tee to threaded ½” PVC connector): 2”
• ½" PVC for down-tube (length determined by stormwater infrastructure depth)

Glue PVC parts together: If using float switch, follow steps in italics

• Glue PVC cap with float switch wires to one end of battery-length PVC.
• Glue that piece to end of PVC tee.
• Glue electronics side piece to the other end of the tee.
• Insert 3D printed indexing part up from bottom of ½” hole in tee (big side up).
• Glue short ½” piece to PVC tee.
• Glue ½" union to end of short ½” piece with the female part up (like the picture at the start of the manual).
• For the sensor (bottom) end, glue the 1” to ½” reducing adapter to the 1” NPT to 1” Socket connect adapter (note that the italicized part is all one piece).
• Glue ½” PVC tube (the long one) which has been cut to the correct length or longer to the 1” to ½” reducing adapter.
• If ½” tube has been cut to the correct length, glue the remaining part of the ½” union (may still be attached to the tee) to the tube. Otherwise, leave this un-glued until the correct length has been established. We recommend saving this step until just before sensor installation in the field to allow for last-minute adjustments to ½” PVC length.

Electronics Carrier

Open Log Artemis (OLA)

OLA sensor is delicate and susceptible to static discharge. Set on static mat or static free bag (the thing it came in).

• FOR THIS ALKALINE BATTERY VERSION ONLY, use an x-acto knife or similar to cut the MEAS jumper on the OLA board (as described on https://learn.sparkfun.com/tutorials/openlog-artemis-hookup-guide/hardware-overview under the “VIN Pin” section). The consequences of this are that the OLA will always need to be powered by battery or, in order to power the OLA from USB or the lithium battery port again, those pins will have to be connected back together (e.g. with a jumper). Be certain that the battery is not connected if these pins are connected back together.
• Solder the 8-pin header on the OLA board by inserting it into the 8 holes on the OLA, long pin side up. Try to get the header pins perpendicular.
• Insert formatted micro-SD card into OLA. Be careful so that the card holder on the sensor doesn’t fail, listen for the click.
• Attach OLA to 3D_printed carrier with M3x6mm Socket head bolts so that USB-C and battery ports are facing outwards. Screws should self-tap into plastic. When securing any device, be careful to not over-tighten and strip the threads.

Bluetooth (BLE) Board

The current design uses the Adafruit Bluefruit LE UART Friend board.

• Solder the 8-pin header on the BLE board by inserting it into the 8 holes on the BLE, long pin side up. Try to get the header pins perpendicular.
• Attach BLE board to electronics carrier using 2 small (M2.5) bolts. (I think that the holes are smaller and the M3’s won’t work, but not sure.)

Electronics Cable

The electronics cable connects the OLA, the BLE board, the batteries, and optionally the float switch. The connectors pictured are, from left to right, battery connector, (optional) float switch connector, OLA connector, and BLE board connector.

The connectors pictured are, from left to right, battery connector, (optional) float switch connector, OLA connector, and BLE board connector. Wires between the two connectors will be much shorter.

• All wires can be small gage (28-22 gage or so).
• Lengths from OLA to BLE can be around 6” (the boards are mounted quite close to one another).
• Power wires can be left at the length of the pigtail on the providing that the wires on the battery holder are long enough to easily reach outside the housing.

Color assignments for the wire are as follows (Tx means Transmit, Rx means Receive):

• Black: Ground
• Red: Power
• Green: OLA Tx (BLE Rx)
• Yellow: OLA Rx (BLE Tx)
• Brown: Float switch signal

Connections are made as per the following diagram:

• The battery connector comes with pigtails (wires already installed).
• All wires going into Dupont connectors get female socket connectors crimped on them.
• Multiple wires can be attached to a single Dupont connector (e.g. OLA GND) by crimping a single short piece of wire to the connector, strategically placing some shrink tubing on the short wire, soldering the multiple wires to the short wire, and then covering with shrink tubing (not in picture).
• When crimping, it may be necessary to crimp once with the larger die, then again with the smaller. Note that the connectors have two sets of arms which wrap around the wire when crimped. One set wraps around the conductor, and one around the insulator. Wire goes in on the left side (if you are a right handed).
• Make sure each pin is properly seated and locked by giving it a light pull after insertion.
• Use label maker to make a label to go on the face of the shroud that does not have holes/gaps in it (“Inward” or “Outward” depending on how you insert the wires in the shroud).
• Insert 8 pin connectors onto OLA and BLE boards. Connectors aren’t polarized, so make sure orientation is correct and shroud isn’t offset from pins.

If using float switch:

• Attach one black and one brown wire to wires coming from float switch (through epoxy) long enough to pass through other end of sensor housing.
• Crimp male Dupont connectors on the black & brown ends and insert into a 2 position shroud.

Pressure Sensor

The wires from the red Bar02 pressure sensor must be soldered to wires that connect to the OLA data logger.

Extend enough wires to the sensor so that it can be easily connected to the OLA during assembly. The length of wire used will depend on the length of ½” PVC. Use enough wire so that the cable reaches comfortably out the end of the ½” PVC housing for ease of assembly.

Connectors (as shipped)

• Grove connector, from the sensor (the wires are tinned, 4 conductor, <22 gage): o Black = ground o White = SDA (data) o Green = SCL (clock) o Red = power

• Qwiic connector (goes to data logger): o black = GND o red = 3.3V o blue = SDA o yellow = SCL

To extend the wires, add heat shrink and solder wires in so that the following connections are made when complete:

• Black (grove) --> black (qwiic)
• White (grove) --> blue (qwiic)
• Green (grove) --> yellow (qwiic)
• Red (grove) --> red (qwiic)

Install sensor in the 1" PVC threaded plug

• Drill a small starter hole to guide drilling a 10mm (or 25/64” on the step bit) hole in the center of the cap.
• Fasten the sensor into the hole. Sensor O-ring goes on the outside of the cap.
• Once the sensor is screwed inside the housing, needle nose pliers can be used to tighten.
• Apply non-hardening thread sealant to threads of the plug and screw into 1” NPT to 1” Socket connect adapter.

Final Sensor Assembly

If using float switch:

• Attach float switch to 3D-printed float switch carrier with two 8-32 x 1” stainless steel machine screws and add two 8-32 nylock nuts.

• Attach float switch carrier to ½” pipe.

• Insert battery packs into long end of housing. If using float switch, keep float switch wire accessible.

• If not using float switch, attach rubber Quik Cap to end of housing with batteries.

• Insert electronics carrier board while connecting sensor cable, battery cable, and optionally float switch.

• Insert desiccant and foam padding to eliminate internal movement.

• Attach second rubber Quik Cap to open end of housing.