[Amps] soft start, how to determine if needed?

[Alex Eban]

As far as possible, USE ONE!!!!! 
First, the cold resistance of a tube's filament is as low as one tenth of
the warm filament, so inrush currents can reach 10 times the operating
value.
Second, inrush current of a HV power supply can reach a hundred amperes,
measured with a Tektronix current probe. If nothing else, that current can
weld the switch contacts!
I don't have to tell you that the stresses on the rectifiers don't do any
good and the capacitors are also badly stressed.
Today, almost all integrated circuits intended for power supply control
incorporate some form of soft start circuitry, precisely for reducing these
stresses.
Use step start or soft start, it's very cheap insurance.
Alex	4Z5KS

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Felipe Ceglia - PY1NB
Sent: Tuesday, February 23, 2010 3:34 PM
To: Amps at contesting.com
Subject: [Amps] soft start, how to determine if needed?

Hi folks,

Regarding this recurring topic about soft starting...

How can one determine if it is needed or not?

Should HV be soft-started as well?

What would be the best math to determine the soft-start dumping resistors?

73,

Felipe - PY1NB

--
Felipe Ceglia - PY1NB
----------------------------------------------------------------------------
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PR1T team member /// Rio DX Group member /// Araucaria DX Group member
http://www.dxwatch.com /// http://reversebeacon.net ///
http://riodxgroup.dxwatch.com

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