Minimum current through psu choke to reach nominal H?

Get technical support here for your Lundahl Tube Power Supply Chokes, Filament Chokes, Plate Chokes, Interstage transformer, Grid Chokes, Signal Input transformers, Moving Coil transformers, Microphone transformers, Digital Audio transformers, SE or PP Tube output transformers, air gapped mains transformers, or the Lundahl problem solver series.

Minimum current through psu choke to reach nominal H?

Postby MaciekP » Wed Dec 25, 2013 7:05 pm

Hello,
Do you know what is a minimum mA current you have to run through lundahl choke like LL1673 20H max 100mA to have the nominal 20H inductance? Is any rule? Is it 30, 40% of nominal current?
MaciekP
 
Posts: 15
Joined: Wed Dec 04, 2013 9:14 am

Re: Minimum current through psu choke to reach nominal H?

Postby MaciekP » Thu Dec 26, 2013 10:49 am

Btw, this is not a choke input question setup and minimum current to make it working, but rather choke only charakteristics and usable current range. At one end we have the max core tesla limitation for a particular core gap to handle DC current, at the other end we have a minimum current to enable the inductance generation
MaciekP
 
Posts: 15
Joined: Wed Dec 04, 2013 9:14 am

Re: Minimum current through psu choke to reach nominal H?

Postby J. Leven » Tue Apr 07, 2015 8:00 am

perhaps you should ask Per Lundahl
J. Leven
 
Posts: 171
Joined: Fri Jan 13, 2012 12:27 pm

Re: Minimum current through psu choke to reach nominal H?

Postby Jac19 » Sun Feb 28, 2016 11:01 pm

Sorry Maciek, I do not have very much time to check the forum often.

If you ask me, there is no minimum current, as long as you take a few mA.

Only when you measure it with an inductance meter, the core is struggling against the reversal of the magnetic direction all of the time, and it's a big piece of iron. So then a 20H choke appears may be 8...10H only, but that is because of iron loss in this micro signal range. Specially when tested at 1kHz. However ar 50Hz and DC current, this effect is gone, and you get a nice 20H.
Jac19
 
Posts: 21
Joined: Sun Dec 29, 2013 10:54 pm

Re: Minimum current through psu choke to reach nominal H?

Postby RhythMick » Wed Sep 13, 2017 2:46 pm

I believe the quick "rule of thumb" for LC filter is

Critical Choke Current = Voltage / Inductance

So for example with a transformer secondary of 400-0-400 and a tube rectifier drop of 50V, the first choke sees 350v. If it is (say) 20H, then you must ensure that at least 17.5mA flows to avoid the voltage rising.
RhythMick
 
Posts: 1
Joined: Wed Sep 13, 2017 2:43 pm


Return to LUNDAHL FORUM

Who is online

Users browsing this forum: No registered users and 2 guests

cron