Question about current ratings of Hammond 300 series power transformers. - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 2nd April 2009, 07:12 AM   #1
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Default Question about current ratings of Hammond 300 series power transformers.

Hi all. If you had a circuit that required 85mA would you hesitate to use a Hammond power transformer rated for 100mA? Also, if the filaments of said circuit required 1.8A would you use the 2A winding on the same transformer? I don't want any problems in the future!
__________________
Gavin
  Reply With Quote
Old 2nd April 2009, 07:27 AM   #2
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
I would call that the "perfect match" transformer myself

Cheers!
  Reply With Quote
Old 2nd April 2009, 07:40 AM   #3
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Quote:
Originally posted by Geek
I would call that the "perfect match" transformer myself

Cheers!

Cool! Last question. Is a 125-0-125v transformer considered a 250v center tapped transformer?
__________________
Gavin
  Reply With Quote
Old 2nd April 2009, 09:00 AM   #4
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
Yes, it is!

Sounds like you're building a little SE power amp or a preamp with 6-8 tubes?

Cheers!
  Reply With Quote
Old 2nd April 2009, 02:41 PM   #5
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Quote:
Originally posted by Geek
Yes, it is!

Sounds like you're building a little SE power amp or a preamp with 6-8 tubes?

Cheers!
SE 12B4A amplifier. A 1.25 watt monster!
__________________
Gavin
  Reply With Quote
Old 2nd April 2009, 08:41 PM   #6
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Quote:
If you had a circuit that required 85mA would you hesitate to use a Hammond power transformer rated for 100mA?
If you mean 85mA ac measured from the transformer then that would be OK.

But if the 85mA is the current taken from the dc (rectified) supply then you'll need more like a 200mA rating. The value of the transformer current depends on the value of capacitance after the rectifier, and the whether it's choke or cap input architecture.

work out the current by using PSUD2:

http://www.duncanamps.com/psud2/index.html

this works near perfectly on Linux platforms (using the WINE environment) so you can dump that Conficker-riddled Windows and use DIY friendly OS

http://www.kubuntu.org/
  Reply With Quote
Old 2nd April 2009, 09:30 PM   #7
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
But if the 85mA is the current taken from the dc (rectified) supply then you'll need more like a 200mA rating.
Hammond transformers are specified for DC current draw. From their web site:

"High voltage current is D.C. using C.T. Full Wave rectifier - capacitor input".

I am guessing that we are talking about a 369AXP which will make about 150 to 160 volts DC (just my guess) using solid state diodes and a capacitor input filter. There would be no problem drawing 100 mA from this supply. Even more could be drawn if you are running it on 60Hz since the 300 series is rated for 50Hz.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 3rd April 2009, 05:58 AM   #8
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Well I wanted to use this PSU:

http://www.welbornelabs.com/ps10.htm

but I can't find the right transformer for the job. I need a 360v-400v center tapped transformer that will supply at least 150mA. Any suggestions? Hammond does not make such a animal.
__________________
Gavin
  Reply With Quote
Old 3rd April 2009, 06:02 AM   #9
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
I suppose I could stick with a 5AR4 rectifier and use a Hammond 370FX. I'm assuming that the 5AR4 will drop some of the excess voltage. I would like for the regulator to run cool without having to drop too many watts to get to the target voltage of 215v.
__________________
Gavin
  Reply With Quote
Old 3rd April 2009, 10:50 AM   #10
diyAudio Member
 
Ty_Bower's Avatar
 
Join Date: Mar 2007
Location: Newark, DE
Have you tried looking through the .pdf of all Edcor's power transformers? They might have something in there...

http://www.audiotransformers.net/for...hp?topic=198.0

The first one I see might be an XPWR105. It says it is good for 360 VCT at 250 mA, and 6.3V at 3 amps. There might be other candidates in the list too.
  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
Quality of Hammond 300 series power transformers compared to 200 series? G Tubes / Valves 10 3rd August 2012 07:32 AM
Hammond PT power ratings dsavitsk Tubes / Valves 4 23rd August 2009 08:23 PM
Question about Allied & Hammond Power Transformer Ratings Bitrex Tubes / Valves 2 6th March 2009 07:31 AM
Quality of Hammond 1600 series transformers and a question about loading. G Tubes / Valves 2 24th March 2008 12:31 PM
Two transformers in series, what happens to the ratings? Jeremy_Wolf Solid State 21 13th January 2002 06:13 PM


New To Site? Need Help?

All times are GMT. The time now is 02:04 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