Making a capacitive dropper - UK Vintage Radio Repair and Restoration Discussion Forum

Neil Purling · 18th Jul 2016, 3:01 pm

I am making a capacitive dropper for my pre-war Little Maestro. It has to be 4.2uf, which is of a 4uf and two X2 rated 0.1uf. However... The voltage rating of the X2 capacitors is less than the 450V motor-run capacitor at 275V.

peter_sol · 18th Jul 2016, 3:11 pm

If that is 275V AC they should be fine.

G8HQP Dave · 18th Jul 2016, 4:35 pm

The difference between 4uF and 4.2uF is 5%. Not worth bothering with, and possibly within the tolerance of the 4uF anyway.

Sideband · 18th Jul 2016, 8:47 pm

Quote:

Originally Posted by Neil Purling

I am making a capacitive dropper for my pre-war Little Maestro. It has to be 4.2uf, which is of a 4uf and two X2 rated 0.1uf. However... The voltage rating of the X2 capacitors is less than the 450V motor-run capacitor at 275V.

Perfect! No problem with that as the X capacitor will be rated at 275V AC. It's designed for direct connection across the mains. It will have an easier life in its proposed application.

18th Jul 2016, 3:01 pm	#1
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Making a capacitive dropper I am making a capacitive dropper for my pre-war Little Maestro. It has to be 4.2uf, which is of a 4uf and two X2 rated 0.1uf. However... The voltage rating of the X2 capacitors is less than the 450V motor-run capacitor at 275V.

18th Jul 2016, 3:11 pm	#2
peter_sol Octode Join Date: Aug 2003 Location: Welwyn Garden City, Herts. UK. Posts: 1,906	Re: Making a capacitive dropper If that is 275V AC they should be fine.

18th Jul 2016, 4:35 pm	#3
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Making a capacitive dropper The difference between 4uF and 4.2uF is 5%. Not worth bothering with, and possibly within the tolerance of the 4uF anyway.