Small beginner amplifier and hello :) - Page 2 - 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 19th November 2008, 12:48 AM   #11
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Whoa, just looked at that schematic- DEADLY dangerous!!!!

At minimum, use an isolation transformer. This was the kind of thing that was banned decades ago after enough people got fried.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 19th November 2008, 12:51 AM   #12
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Morse's 6BM8 SE

Pics of my 6BM8 - The Gnat....

Click the image to open in full size.

No bang, no flash, just music!

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 19th November 2008, 12:53 AM   #13
diyAudio Member
 
Join Date: Apr 2003
Location: Portland,Oregon
Blog Entries: 4
Send a message via AIM to DigitalJunkie
Quote:
Originally posted by SY
Whoa, just looked at that schematic- DEADLY dangerous!!!!

At minimum, use an isolation transformer. This was the kind of thing that was banned decades ago after enough people got fried.

Dang,I glazed right over that the first time I looked at it.. My "minds eye" saw a separate HV secondary.
  Reply With Quote
Old 19th November 2008, 03:31 PM   #14
diyAudio Member
 
Join Date: Nov 2008
Location: Denmark
Thanks for all the warnings and links

As im "used" to work with live wires through my job as electrician and my latest tesla coil was fed by 2300Vac/500mA I am very careful around it.

I will look at the other schematics when I get home from work.

I just wanted to show you that I build the dangerous version without isolation from mains.

Picture here: http://gratisupload.dk/download/18027/view/

And that it acutally works, as I talked about earlier I thought the power trafo was the wrong way around as I missed 300V but had 180V instead, I will have to turn it back to 180V as I were feeding this poor little tube 380VDC last night and had red plates in short run times.

So remaking it with some fuses on my just ad dangerous power transformer as its just that old, lowering plate voltage and enclosure it in something
  Reply With Quote
Old 19th November 2008, 03:32 PM   #15
diyAudio Member
 
Join Date: Nov 2008
Location: Denmark
A note on isolation transformers

Secondary neutral can be grounded to avoid floating potentials

Shortcircuit current is lower as its determined by the secondary sides impedance, in difference to the 6kA shortcircuit current we have on mains in households, in Denmark.

Using a isolation transformer is not removing any dangerous parts as the secondary side of a 1:1 transformer will still kill you, but you can avoid having potential difference from your amp to other conducting objects in your home, which is why all old electronics mostly were in non conducting enclosures.

If you know what you are doing, using old transformers isnt DANGEROUS, but its a unsafe choice when there is better options
  Reply With Quote
Old 20th April 2009, 10:38 PM   #16
diyAudio Member
 
Join Date: Nov 2008
Location: Denmark
Just wanted to show the final product, the chassis is grounded and measurements from audio in to ground is no more than 20V+

Whatever is plugged to this amplifier is something that I could live on without, knowing there is no isolation or fuses.

Unfortunately youtube muted my video, but then again, listening to a tube amplifier recorded by a compact camera, compressed, uploaded to youtube and then played on computer speakers.. not a huge loss

http://www.disorder.dk/?page_id=469
  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
Beginner's Gainclone, HiFi LM1875, The Amplifier Board danielwritesbac Chip Amps 417 3rd July 2014 09:46 AM
Beginner's Gainclone, LM3875, The Amplifier Board danielwritesbac Chip Amps 37 22nd May 2008 06:43 PM
real beginner amplifier inadaze Solid State 8 10th May 2007 03:45 AM


New To Site? Need Help?

All times are GMT. The time now is 04:23 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