Now I know what this Tranny can do - 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 4th January 2009, 01:17 PM   #1
Tarzan is offline Tarzan  Belgium
diyAudio Member
 
Tarzan's Avatar
 
Join Date: May 2004
Location: Genk
Default Now I know what this Tranny can do

Hi,
A Happy New Year to you all and a lot of projects for 2009.

Many power supply tansformers are available and all can be used for what they are intended to do.
But, and here it comes...
It must be clear that this is done on trafo's where no technical data is available.
If any body can give figures for trafo's used in excisting amps, I will be glad and happy to receive it.
But I looked around and could find none.

How can a trafo (wich ever one) where no data is available like VA power, max current for each secundary etc be tested?
We do not want to know the primary side. That's assumed to be known.

How much can there be squeezed out of a transformer.
Take for instance a simple one:
The trafo for a Fender Champ, labeled 125A35A.
Assume we apply a load (made by adjustable resistors) to each secundary and apply a primary voltage.
We now adjust the loads until the secundary voltage drops by 10%.
We now the voltage and current, hence the power, the trafo can deliver.
Can we assume that this is a real situation and use these found values as a basis to design an amp around this trafo?
Is 10% good or do we even have to go further, 15 or 20%?

That's it...

Thanks,
Tarzan
  Reply With Quote
Old 7th January 2009, 05:50 PM   #2
Tarzan is offline Tarzan  Belgium
diyAudio Member
 
Tarzan's Avatar
 
Join Date: May 2004
Location: Genk
Funny, there is no reaction?
103 vieuws in a few days!!!

It seems that finding out the properties of a psu trafo is not important.

Knowing what material is used in a resistor and measuring the sonic properties of them (and not to forget caps) is VERY important.
Tweeking preamp stages to the extremes and almost dying for a NOS ECC83 from Telefunken is important.
Calculating the possible riple with choke x or y is important.
Finding a good output transformer and doing calculations for it is important.

But knowing if the power supply trafo is ok; No no.
I have the feeling that all possible tweeking and calculations starts AFTER the PSU trafo.

So we have to pick a trafo from a vendor and assuming it's OK.
Even if it's delivering to much or even barely enough;

"we do not calculate these thingies; we concentrate on resistors, silicon or no silicon cabling. Use of pcb or hand wired. Orange Cap, Blue Caps or Keystone Caps...)"

Well, what do I have to think.
Don't know.
I continue to follow my path and do some measurements on trafos.

Tarzan
  Reply With Quote
Old 7th January 2009, 06:11 PM   #3
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
Use a transformer within its ratings - no worries. PSU Designer program will give you a close estimate of DC output.

If you have a transformer and don't know ratings, there are various ways to estimate maximum output. Voltage drop and power loss can be calculated from winding resistance. And naturally you'll use it well below that to assure that it runs cool...

If the transformer output voltage is dropping 10% under load, it is also dissipating 10% of the power that it's delivering. Can a 50VA transformer dissipate 5W? Probably. Can a 500VA transformer dissipate 50W? NO WAY!
  Reply With Quote
Old 8th January 2009, 07:37 AM   #4
Tarzan is offline Tarzan  Belgium
diyAudio Member
 
Tarzan's Avatar
 
Join Date: May 2004
Location: Genk
Oeps, The tranny number had to be 125P1B; The 125A35A is the Output Tranny...

Not that is makes a difference to the "vast number of reactions"

Thanks Tom for your reply.
Indeed an ESTIMATE can be made by the said calculations.
But that dosn't garantee that these voltages and/or curents are available at full load.
And that's the whole intend of my question.
And voltages do sag with 10% or more. Even in an Ampeg bass amp with 6 x KT88.

I have to write again that we like to start with a clear knowledge of the trafo we like to use or have.
Using a trafo without details of the voltages and currents it can deliver is not the question.

To clarify:
Trafo's are available in three ways.
1. New and with technical data.
2. Used with known data.
3. Used but no technical data except that is used in a Fender, Marshall or whatever.
  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
Another Tranny Question bcrescen Chip Amps 7 26th September 2006 04:42 AM
Tranny Qs? henkel Parts 4 12th September 2006 03:58 PM
What can I do with this tranny? ThSpeakerDude88 Chip Amps 15 28th July 2005 03:29 AM
what should I do with this tranny??? mylesmf Tubes / Valves 6 8th June 2005 11:42 PM
How to use LED with +- 25v tranny? ransom peek Chip Amps 21 28th March 2005 11:55 PM


New To Site? Need Help?

All times are GMT. The time now is 12:47 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