2A3 power supply transformer - 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 11th November 2004, 08:42 PM   #1
diyAudio Member
 
Join Date: Sep 2003
Location: New Jersey
Default 2A3 power supply transformer

I am making a simple 2A3 amp and it is my very first tube amp. In making it, I bought a good price tube power transformer from asia with the spec of primary @110V and secondary @ 380VAC. Because the US is running at @120V, therefore, the new secondary output became 418V, instead of 380V for 2A3's design.

Since I am new in tube, can I use the 2A3 working under 418VAC (before rectifier 5U4GB)? Should I need to modify anything to accomondate the higher voltage?

Thanks,

Thomas
  Reply With Quote
Old 11th November 2004, 11:07 PM   #2
diyAudio Member
 
Join Date: Jun 2002
Location: Denver, CO
Default should be fine

The difference in transformer secondary voltage between this one and the one you describe is not very significant. If you are trying to get everything perfect, then maybe you should be concerned but in reality you could change a few values and arrive at the correct voltages with no trouble. It is a lot easier to reduce voltage than make it up...sorta like making something shorter is much easier than making it longer!

Please realize that all voltages will change slightly using this transformer vs the one called for.

Besides that, the voltage supplied to your house is not exactly 120v all the time and everyplace.

Yes, you will need to check calculated voltages to determine if you have any problems but I'll bet you are probably ok.

Can you analyze circuits, voltages, drops, etc?
  Reply With Quote
Old 12th November 2004, 01:24 AM   #3
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
You can lower the first PSU cap to "tune" the voltage to the desired level.
  Reply With Quote
Old 12th November 2004, 01:38 AM   #4
diyAudio Member
 
Join Date: Sep 2003
Location: New Jersey
Quote:
Can you analyze circuits, voltages, drops, etc?
Fragman56:

Yes, I am trying to learn, but not yet able to figure it out right away!

Quote:
You can lower the first PSU cap to "tune" the voltage to the desired level.
Arnoldc:

Do you mean lower the first cap value? currently my first one is 100uF/450V.

Thanks to you both.

Thomas
  Reply With Quote
Old 12th November 2004, 01:40 AM   #5
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Download a copy of PSUD and start tweaking some values to get it in the range you want. It's free and easy to use. Choke input (LC) would be about right for a 418Vac secondary and as arnoldc has said, you can add a small (<3uF) cap before the first L to tweak the final voltage. PSUD will show you what's going on for this small cap, but I've never found it accurate enough to design and apply directly to the circuit. Start low and build up in increments until it's correct.
  Reply With Quote
Old 12th November 2004, 03:28 AM   #6
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
Thomas,

100uF seems too high as first cap even for a 5U4-G. I will start with 2uF - L - 100uF and as always PSUD will be highly recommended.

You need to find out how much current is used by your circuit. In a 2A3 it will be around ~50mA I suppose + the drivers.
  Reply With Quote
Old 12th November 2004, 01:24 PM   #7
diyAudio Member
 
Join Date: Sep 2003
Location: New Jersey
All,

Thanks for the good reminder! I do have a copy of PSUD and forgot to simulate it! (I did use a lot in my solid-state, but forgot to do one in my new tube one, because I thought it is OK by simply follow the schematic).

Thanks,

Thomas
  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
No transformer power supply tryonziess Solid State 10 6th August 2007 03:42 PM
Power Supply Transformer bal704 Chip Amps 12 8th November 2006 12:08 PM
Help with this transformer/ power supply Ionstorm Parts 0 7th January 2004 10:31 AM
zen 4 power supply transformer schatz Pass Labs 1 5th September 2002 08:08 PM


New To Site? Need Help?

All times are GMT. The time now is 12:06 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