PS choke (Spyder)

[antonis]

Just a quick query..

I'm building an 8 output power supply (Spyder style) with 4 2X12/1.8VA transformers, bridge rectifiers, 78L09 regulators with 220μF IN and 22μF+100nF OUT caps and IC protecting diode (Out -> In).

Does it worth to place a series inductor (100 - 220 μH) between bridge and regulator..??
(or it's just a waste of time/money/space ??) 

[digi2t]

Built mine as per Geofex spec's. Works perfectly. Dead quiet.

[R.G.]

Does it worth to place a series inductor (100 - 220 μH) between bridge and regulator..??
(or it's just a waste of time/money/space ??) 

Worse, it's a bad idea. It makes the output voltage lower at the filter cap.  There are a number of other side effects, many of which are bad. Of course 220uH is too small to make a big difference, so maybe it's just useless after all.

[antonis]

Thanx guys...

(I was also suspecting some nasty side effects like elapsed diode conduct time but I though to give a chance to my junkbox chokes - maybe another time in a parametric EQ or similar build..)

[R.G.]

Thanx guys...

(I was also suspecting some nasty side effects like elapsed diode conduct time but I though to give a chance to my junkbox chokes - maybe another time in a parametric EQ or similar build..)

Inductance after the diodes does make it easier on the diodes by increasing the diode conduction time. But it also makes the output DC voltage vary - a lot. Your inductances are too small to give much effect, but for larger inductances, the voltage starts at the no-inductance value  and as current increases the output voltage drops to about 62% of the no-load voltage.

Even the pros don't use inductance input power filters any more except in very unusual circumstances.