THE REED SWITCH
You will always need these reed switches for the Tricorder because there are no visible switches to activate it. The reed switch comes in two types but in many forms of packaging. I got these black ones because it looked more robust than the fragile glass types which keeps failing on me. You can read more about the reed switches here, courtesy of RS Catalogue. The NO (Normally Open) is very common and like its name, breaks the circuit when there is no magnetic field. The NC (Normally Closed) is the opposite where it makes a circuit connection when there is no magnetic field.
So, it is NC to detect the Flap being opened and NO to detect the closing of the flap. Sometimes it is hard to differentiate them if you use the black ones like one in the image below. For the glass tube version, you can tell because one side of the glass tube has TWO legs. You will need a magnet and a continuity tester such as a multi-meter if you mixed them up by accident.
THE NORMALLY CLOSED REED SWITCH
The reed switch that I have has a very funny name of, ‘MKA14103 GPS-14B’. It is technically a NO switch as with all reed switches, this type is easier to manufacture. They inserted a small magnet or something to turn it into a NC switch.
SOLDERING THE REED SWITCH
If you look at the image below, you will see that I did solder the reed switch about 1.2cm away from the board. This allows me to adjust the switch so that it can detect the flap’s magnet and later, I can fix it with epoxy putty. Remember, I cannot use hot-melt glues as this 3D printed resin is heatproof until 54ºC.
RE-WIRING THE FRONT ARRAY
The re-design of the Top Panel PCB has an additional features which distributes power from the battery to the other boards. So, when the NC reed switch connects, the whole Tricorder will start to function. So, I have to re-solder the power cables of the Front Array away from the battery and into the Top Panel PCB.
