All-semiconductor regulated HT PSU

[Skywave]

Update to circuit of PSU, Aug. 5, '14.

Modifications (above posts refer).
► 12-v. Zener diode now added: cathode to gate of FET.
► 1-kΩ resistor added to base of Q4.

► Drawing error: between the 240 v.a.c. mains 'L' input and the switch, a 1-amp. A/S fuse should be shown.

Post-modification tests: no change in performance was detected.
Measured hum & noise level at 250 v.d.c. / 100 mA output: 5 mV. peak-peak.

Al.