Secondary turns scale the secondary voltage by the turn ratio, so changing turns can keep the winding below a ceiling, land on it, or exceed it. With 4 primary turns and 12 V primary drive, 1, 2, and 3 secondary turns give 3, 6, and 9 V against a 6 V limit exactly for the ideal transformer model; real transformers add leakage inductance, winding resistance, core saturation, parasitic capacitance, regulation, heating, frequency dependence, and voltage measurement uncertainty.
Secondary turns can pass, touch, or fail a voltage ceiling. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Secondary turn row 1
Primary turns stay 4, primary voltage stays 12 V, and secondary turns 1 give secondary voltage 3 V against a 6 V ceiling, so margin is 3 V.
m=3Vpass
Secondary turn row 2
Primary turns stay 4, primary voltage stays 12 V, and secondary turns 2 give secondary voltage 6 V against a 6 V ceiling, so margin is 0 V.
m=0Vpass
Secondary turn row 3
Primary turns stay 4, primary voltage stays 12 V, and secondary turns 3 give secondary voltage 9 V against a 6 V ceiling, so margin is negative 3 V.