Making XO sensors/How to connect sensors

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This details steps to build a low cost probe for connecting sensors to the XO for use in Measure and other activities that can read sensor input.

In general, you wire the sensor to a 3.5mm audio jack, and also to a USB connector if it requires voltage.

It'd be good to have these tools - A soldering iron, some soldering wire, a wire cutter/wire stripper and some insulating tape
Wire stripper
Soldering wire
Some connecting wires
3.5mm audio jack (stereo or mono, any would do)
A USB cable, or even a USB connector would do
The audio jack/connector
Cut two pieces of wire and strip them at the ends
Solder the wires to the connector as shown. Do make sure to have an identification mark (eg. a knot) to differentiate between both the wires.Call the wire connected to the central terminal as "Vin" the wire connected to the outer terminal as "Gnd"
Take the USB cable/connector
Cut it in the middle and strip the wires
We only need the red and the black wires.The USB port provides us with a source of +5V supply. Let's call the red wire as "+ve" and the black as "Gnd" and make the black one and the "Gnd" defined in audio connector as one, by connecting them together.
The audio connector goes into the pink MIC input jack
The USB connector goes into the USB port

To summarize, do remember that we have identified three terminals

  1. The "Vin" terminal
  2. The "+ve" terminal
  3. The "Gnd" terminal (the Gnd of audio connector is connected to Gnd of USB connector"

Other sensor instructions

Other pages describe how to build specific kinds of sensors.