04 – logger and sensor position

A project log for micropower micrologger [mPmL]

A set-and-forget I2C/digital datalogger. Size: 25.3x 18x 10mm incl. battery. Runtime: > 1year

JanJan 08/12/2018 at 13:230 Comments

Update 10.10.2018 - sensor glued into comb for test purposes

Today I tried "melting in" a sensor into a pre-formed comb / foundation. The 4-stranded copper wire is wrapped around the stainless steel wire with 3 turns, then the wax foundation is laid on top of it. Later, the stainless wire is heated by putting some amps through it and the foundation sinks in a bit. (Haven't done this step here).

What I have done is the wrapping part and aligning the test-sensor:

Then I heated a small metal rod and pressed it on the sensor so it melts into the wax foundation:

The other side looks like this:

I added a drop of molten wax so the bees won't abandon the cell because of a foreign body. Hope that'll do :)

The micrologger has that name for a reason :) It is so small, that it can be placed right in the frames which are put in the bee hives! Here you see a frame with a wax foundation:

wax foundation

The top "bar" is 20mm wide, that's why I decided to shrink the logger to 25x20mm. I use very thin battery-pack heat shrink tubing to protect the circuit.

here goes the logger

It will be glued in the space you see outlined.

To not disturb the bees while building the cells, I can't use normal multi stranded wire to connect the sensors. So I chose enameled copper wire of 0.15mm diameter.

0.15mm enamelled copper wire

4 strands are first color coded and then twisted with a hand drill. The finished wire is 0.4mm in diameter, which can easily be routed on the pre-made wax foundation plates. It is quite durable, so you can bend it a few times without breaking the insulation.

The next picture shows two different packages:

TO-92, left and SOT-23 next to it. I just ordered my TMP112 sensors which are even smaller than the SOT-23 package seen here. Will be quite the hassle soldering wires directly to it but let's see how/if it works.
I want to add it directly into the cell bottom!