Dual-winding supply front end
8 parts
A transformer with two primaries and two secondaries, wired the way a universal-input supply uses it: the primaries in SERIES across a 240 V line, and each secondary feeding its own diode and reservoir to give two independent output rails. The windings are a real mutual-inductance model, so the coupling coefficient and the winding inductances — not an assumed turns ratio — are what actually set the secondary, which swings ±10.16 V here. Each rail sits between 8.46 V and 9.01 V, so 0.55 Vpp of ripple on a 470 Ω load; the reservoirs ship pre-charged to 8.75 V so the scope opens in steady state rather than during the charge-up.
- V1 240Vrms·60Hz
- TX221 1:0.06
- DSW1
- DSW2
- C1 470µF
- R1 470Ω
- C2 470µF
- R2 470Ω
