This is a very basic question, but tutorials tend to leave out the obvious, which is a problem for those who are trying everything for the first time.
The following image is from a tutorial by Andrei of electronoobs and was taken from https://electronoobs...ino_tut24_2.php
and it seems to me to be a really useful tutorial
It is for controlling a peltier chip using an Arduino, with MOSFET and Rotary encoder.
My question is about the 12V supply for the peltier itself. The Arduino has its 5V USB (or even 12V, which it will convert), but it can't deliver 12V to the peltier, so I assume that the right hand side of that circuit needs its own power supply.
The schematic has two red 12V DC arrows, both point the same direction (out of the circuit, up), and this is what is confusing me. It would make sense to me if the 12V was coming in at the resistor and going to the MOSFET first, and then to the peltier (or 12V heater in his schematic). In that case I would expect the arrows to be pointing down (towards the resistor) into the MOSFET, and the red arrow from the heater to point upwards (as in the schema), i.e. returning back to the power source (in practice the negative, or black wire).
Perhaps the arrows pointing in the same direction is some electrician's convention that I am unaware of, or perhaps Andrei assumed that it was obvious and wasn't too concerned about how he drew his arrows.
I know this is going to sound really silly to anyone who has wired a circuit before (I have wired circuits but not micro, or as PC builds where I only need to plug stuff into a mobo), but I need to be sure before I risk frying something.
We use to talk of "standard idiot proofing", well I am the standard idiot here!
Thank you for your tolerance
PS I didn't email Andrei to ask him because his Q&A forum is full of spam and I am not sure what's up there, plus he has a monthly rate for answering questions, and I currently only have one. Also, I am planning to use this for an astro application (controlling bolt-on cooling for a ZWO camera - well I know it probably won't work so well, but really I just want to learn about what an Arduino can be used for) so if I ask astronomy people I might get more specific tips.
Edited by Ivor Redtorch, 04 December 2020 - 01:10 PM.