Is audio transformer primary/secondary correct?

[thesnert]

Hi WendyTeslaburger

thank you very much for this project and the effort you've put into it. In the process of building my first board (v2) I've realized when installing the audio transformer that the schematics shows it with its primary (pin 1-3) oriented towards the amplifier circuitry and its secondary windings pointing towards output (datasheet: https://www.mouser.ch/datasheet/2/449/Yuetone_XC-600127-1212403.pdf).

If I compare the schematics with the mk312 (e.g. https://github.com/CrashOverride85/mk312-bt/blob/master/schematics/V1.4%20Main%20Boards/MK-312BT%20V1.4%2005-19-2019%20Board%20Layout.png), you'll see that they've installed their transformer with the secondary pointing towards the amp circuitry. Also @CrashOverride85 uses them in reverse in their zc95 built (https://github.com/CrashOverride85/zc95/blob/main/docs/Build.md; "Note that the transformers are used "backwards" - the side labelled primary goes to outputs.")

Thanks for clarifying!

[Misaka13514]

I think you are right. The datasheet states that the number of primary turns is 400 and the number of secondary turns is 60. To achieve the boost effect, the side with more turns (i.e. the primary) needs to be connected to the output.

Having used this connection method in my own build (same as #1, pictured in #8), I think the schematic needs to be updated.