I am doing some beginner project through YouTube and some books. So now I need a transformer which primary side has 3 wires while secondary side has only 2 wire. It consists 40 0mH coil(called the primary) and 2 mH coil (called the secondary) wrapped around an iron bar. For better understanding I have given a schematic of a particular small project So what kind of transformer this is? And what will be the other numbers?
On your previous question the small AC per transformer will work using the centre tap and one side only like this schematic.
240V/12V means Z1/Z2= 20:1 inductance ratio. To lower the source impedance of caps to speaker and thus drive more current force on cone.
The voltage ratios are the same except your source 9Vdc with limited current