Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th November 2010, 02:47 AM   #1
wabun is offline wabun  United States
diyAudio Member
 
Join Date: Sep 2009
Blog Entries: 1
Default Fluorecent choke for power supply

Can I use fluorecent choke (36W lamp )as PSU choke ? It is much cheaper and has DC resistant of ~ 80 Ohms.. I do not have a LCR meter, donno what is the Henry value.. any experience can share ?
  Reply With Quote
Old 12th November 2010, 08:45 AM   #2
diyAudio Member
 
stormsonic's Avatar
 
Join Date: Aug 2008
Measured some of them, 0.3 - 1.5 H, depends on type.
You need to measure your choke, then use PSU Designer.
They can be used for low-power loads (preamps, tube gear, etc.).
  Reply With Quote
Old 12th November 2010, 09:02 PM   #3
diyAudio Member
 
Join Date: Sep 2010
Location: Melbourne
I used a 250W mercury vapour ballast (choke) for a CLC filter once and it worked fine even though it was not designed for DC. The henry value can be calculated by knowing the details of the lamp it drives.

Low loss types have a lower DC resistance and more inductance, for comparison @240V 36W, a standard ballast has a 40 ohm DC resistance and a low loss type has a 23 ohm DC resistance.

80 ohms seems like a lot of DC resistance even if the ballast were designed for a 277V supply it should have a similar or slightly lower DC resistance than the 240V 50Hz ballasts I measured.
  Reply With Quote
Old 12th November 2010, 09:45 PM   #4
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
DC will reduce the inductance, as these chokes won't have an air gap. You need to measure it with DC present, or just build a PSU and measure the output. What you can't do is measure the inductance at zero DC and then simulate a circuit assuming it retains that inductance.
  Reply With Quote
Old 13th November 2010, 07:09 AM   #5
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by DF96 View Post
DC will reduce the inductance, as these chokes won't have an air gap. You need to measure it with DC present, or just build a PSU and measure the output. What you can't do is measure the inductance at zero DC and then simulate a circuit assuming it retains that inductance.
They have distributed high reluctance sections, because they have to operate as power inductors, and are not allowed to saturate significantly within their operating range.
The fact that they operate in AC changes nothing.

The parameter to take into consideration for saturation is the instantaneous current.

I just measured a 15W ballast (for 230V). The (cold) DC resistance is 56 ohm, and the inductance is 1.56H (under small signal; at the nominal current, it is normally higher).
The maximum rms current is 0.33A --> 468mA instantaneous.
It could be used up to that current in DC, except it will overheat.

1.5H is not much, but it can be useful tough, and it could be parallel-tuned for 100Hz.
  Reply With Quote
Old 13th November 2010, 03:52 PM   #6
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
OK, I didn't realise they solve the problem in a different way.
  Reply With Quote
Old 15th November 2010, 12:02 AM   #7
wabun is offline wabun  United States
diyAudio Member
 
Join Date: Sep 2009
Blog Entries: 1
Quote:
1.5H is not much, but it can be useful tough, and it could be parallel-tuned for 100Hz.
Does it mean we can parallel the choke and ideally it should behave as follow..

50Ohms ( 1.5H ) || 50 Ohms (1.5H) = 25Ohms (3H)

and the max allowable current will double 0.33 A x 2 = 0.66A ?
  Reply With Quote
Old 15th November 2010, 12:07 AM   #8
diyAudio Member
 
stormsonic's Avatar
 
Join Date: Aug 2008
INDUCTORS
  Reply With Quote
Old 15th November 2010, 03:17 AM   #9
wabun is offline wabun  United States
diyAudio Member
 
Join Date: Sep 2009
Blog Entries: 1
thanks for the point out. I have mistakenly tot inductor & capacitor behave the same. In fact they aren't
  Reply With Quote
Old 15th November 2010, 07:26 AM   #10
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by wabun View Post
Does it mean we can parallel the choke and ideally it should behave as follow..

50Ohms ( 1.5H ) || 50 Ohms (1.5H) = 25Ohms (3H)

and the max allowable current will double 0.33 A x 2 = 0.66A ?
No, I mean you can parallel it with a 1.69F capacitor to increase the rejection at 100Hz (~30dB), provided you already have a conventional filter to remove higher harmonics.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Power supply choke help needed audiobliss Tubes / Valves 4 1st August 2008 03:22 PM
choke for the power supply jarthel Pass Labs 44 2nd July 2007 10:23 AM
choke for an 8v power supply jarthel Parts 0 9th May 2007 02:12 AM
Choke power supply supernet Everything Else 1 12th May 2002 11:33 PM


New To Site? Need Help?

All times are GMT. The time now is 11:17 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2