Stupid Bridge/Diode Question - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 7th February 2006, 07:58 PM   #1
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Default Stupid Bridge/Diode Question

If I build a discrete bridge rectifier using 4x 100V diodes, is the bridge rectifier as a whole rated to 200V?
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 7th February 2006, 08:09 PM   #2
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi richie00boy,
I would think 100V. It is reverse biased on alternate cycles with one end being the rectified voltage close to peak, the opposite goes the other way.

-Chris
  Reply With Quote
Old 7th February 2006, 08:26 PM   #3
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Yes, but the current has to pass through two diodes on the journey. I an interested in the theoretical answer but also from a practical viewpoint as I currently have a bridge made from 100V diodes running off a 45VAC winding and has been given some abuse without blowing.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 7th February 2006, 09:26 PM   #4
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
45 VAC and 100 V diodes is a bit weak. 200 V at least. You must also have incoming voltage transients in mind.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy. Still time for signing up.
  Reply With Quote
Old 8th February 2006, 07:33 AM   #5
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Yes but from a purely theoretical view, is a bridge made from 100V diodes rated to 200V?

As 45V * 1.414 = 63V which when doubled to take into account of reverse bias bridge gives 126V yet my bridge has not blown up.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 8th February 2006, 07:39 AM   #6
moamps is offline moamps  Croatia
diyAudio Member
 
Join Date: Oct 2002
Location: Croatia
Quote:
Originally posted by richie00boy
As 45V * 1.414 = 63V which when doubled to take into account of reverse bias bridge gives 126V yet my bridge has not blown up. [/B]
No.
Reverse voltage on each diode is Vpeak-Vdiode(on)=ca Vpeak
like Chris already said.

Regards,
Milan
  Reply With Quote
Old 8th February 2006, 08:09 AM   #7
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Thank you, that is the kind of answer I was looking for.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 8th February 2006, 08:26 AM   #8
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
So what about half wave voltage doublers? I used 60V diodes on a scheme similar to this

Click the image to open in full size.
Schematic copyright Rod Elliot, sound.au.com

but they blew up with an 18V transformer. Yet 18*2*1.141=51V which should be within their capabilities.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 8th February 2006, 09:31 AM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
a bit off topic but why on earth are you feeding 51Vdc into a 7815/7915? They are almost certain to blow. With or without a load on the end. Or is your circuit only delivering 25Vdc to each?

So back to topic

Is a 4 by 100V diode bridge equivalent to 100V or 200V PIV?
__________________
regards Andrew T.
  Reply With Quote
Old 8th February 2006, 10:04 AM   #10
diyAudio Member
 
Join Date: Jul 2005
Location: North Derbyshire
Quote:
Originally posted by AndrewT

Is a 4 by 100V diode bridge equivalent to 100V or 200V PIV?
Interesting question!

In theory it would be 200V, as the two diodes are effectively in series in each side of the bridge. BUT!, there's no voltage sharing resistors across them, so they won't be accurately balanced - so it will be greater than 100V but less than 200V (the exact value depending on the exact spec of the individual diodes).

Personally, I'd still rate it as a 100V bridge, if you want 200V, then use better diodes! - the price difference is pretty insignificant.
__________________
Nigel Goodwin
  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
diode bridge - 10000uF cap - diode tube - small cap - HV+ engels Tubes / Valves 5 29th January 2008 10:16 PM
hybrid power supply: diode bridge into diode tube engels Tubes / Valves 8 24th September 2007 09:18 AM
Diode bridge as loop breaker question Tyimo Pass Labs 42 9th March 2007 04:21 AM


New To Site? Need Help?

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