Two-cases amplifier, question about power switch - 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 3rd December 2014, 05:40 PM   #1
00940 is offline 00940  Belgium
diyAudio Member
 
Join Date: Sep 2003
Location: Paris
Default Two-cases amplifier, question about power switch

Just a small question about switches and two boxes setups...

Here's the setup: the transformer (40VA, 200vac@100ma and 8vac@2A secondaries) is in an external plastic box. There's a fuse at the entry. A lead with 4 conductors+earth goes to the amp case. The amp case is earthed.

Question is: is it unwise to use a single DPST switch (250V/3A rated) to switch both one line of the 200Vac and one wire of the 8Vac ?
__________________
Ben.
  Reply With Quote
Old 3rd December 2014, 06:11 PM   #2
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
Yes it is unwise to mix low and high voltage circuits in a switch. Why not switch the mains before the transformer?

Rundmaus
  Reply With Quote
Old 3rd December 2014, 06:13 PM   #3
00940 is offline 00940  Belgium
diyAudio Member
 
Join Date: Sep 2003
Location: Paris
transformer box is under the desk, the amp box on the desk ;-)
__________________
Ben.
  Reply With Quote
Old 3rd December 2014, 06:43 PM   #4
jakubg is offline jakubg  Slovakia
diyAudio Member
 
Join Date: Jul 2010
Location: Bratislava
I have a similar setup.
I'm bringing the live wire before transformet to the switch in the top box and back again to the transformer. Tightly twisted together, don't know if it helps.
  Reply With Quote
Old 3rd December 2014, 08:31 PM   #5
diyAudio Member
 
mark02131's Avatar
 
Join Date: Nov 2005
Location: Boston, MA
I like to use relays and a 6v transformer (DC) in the power supply that's always on, then you have a low voltage switch in the amp that turns on the replays for the mains transfomer. You can also add another relay for "standby" that turns on/off the HT.

Then if the power supply and amp ever get disconneted the power supply shuts down becuse the relays loose the 6v on them. I would also put a mains switch on the power supply in the event you want to shut it completly off.
  Reply With Quote
Old 3rd December 2014, 08:37 PM   #6
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
+1
  Reply With Quote
Old 3rd December 2014, 08:41 PM   #7
00940 is offline 00940  Belgium
diyAudio Member
 
Join Date: Sep 2003
Location: Paris
+1, I wish... too much space constraints in there to do that.

If you think it's truly unsafe, I'll remove the switch on the amp and use a switched power bar under the desk.
__________________
Ben.
  Reply With Quote
Old 22nd December 2014, 01:05 AM   #8
00940 is offline 00940  Belgium
diyAudio Member
 
Join Date: Sep 2003
Location: Paris
The solution is rather obvious now that I think of it... I just need to use the power switch to control the 8vac line to the heaters and use the heaters DC supply to control a relay that will in turn switch the B+ AC.
__________________
Ben.
  Reply With Quote
Old 22nd December 2014, 01:08 AM   #9
diyAudio Member
 
Join Date: Feb 2010
Location: Helsinki
When I had the PSU on the floor, I just used my foot to toggle the switch!
  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 Switch Question kstylianos Parts 2 8th June 2012 03:04 PM
Simple Power Switch Question Littlebilly91 Construction Tips 7 29th April 2012 12:27 AM
On/Off Power switch question madisonears Chip Amps 6 29th March 2009 02:36 PM
Newbie question on power switch senderj Parts 5 17th February 2006 10:50 AM
And now a question about power switch... mr mojo Tubes / Valves 13 16th August 2005 02:37 AM


New To Site? Need Help?

All times are GMT. The time now is 06:52 AM.


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