I am studying the Sparkfun Logic Level converter and the basic aim of this is to understand how these BSS138 transistors are used in logic level conversion. I have used transistors before in driving high current motors with MCU's i.e. small time h-bridge configurations. Now I want to use them to make my own logic level converters.
So went to the SparkFun GitHub repo and downloaded the eagle files. Something just does not add up in the schematics for me and I seek clarification around this.
Lets look at how the BSS138 is wired up:
The first thing that strikes me as odd is that I cannot see a earth/ground connection here seems like the low voltage side is connected to the Gate and Source while the High voltage side is connected to the Source.
However there is a clearly defined GND on both the HV and LV side of the board designs and on the schematic? See below:
I must be missing something fundamental here.I can even see how current wuld flow without the BSS138 having some sort of grounding.