Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

LM3x7 HV regulating.
LM3x7 HV regulating.
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
Thread Tools Search this Thread
Old 29th February 2004, 12:50 PM   #1
w00t is offline w00t  Singapore
diyAudio Member
Join Date: Aug 2003
Location: Singapore
Default LM3x7 HV regulating.


I would like to know how to regulate a HV/HT line with the LM3x7 series. I konw I can do so by raising the ground with the use of a zener and have seen a few schematics employing this method, but I'm still not certain what the true generic schematic is like. Those I have seen seems to be 'upgraded' versions.

All versions would be much appreciated. Thanks!

  Reply With Quote
Old 29th February 2004, 06:19 PM   #2
Sch3mat1c is offline Sch3mat1c  United States
diyAudio Member
Sch3mat1c's Avatar
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
It's a bad idea because they only have a range of maybe 40V input. Thus your power supply needs good regulation anyway, because at no-load you have an absolute maximum of say 290V versus a minimum of 250V. A very tight range for anything. Not to mention a 10% variation in line voltage (which is within spec) will take up most of that range.

Better to use a purpose-made HV regulator, either discrete or integrated.

Seven Transistor Labs, LLC
Projects and Resources / Electronic Design and Consultation
  Reply With Quote
Old 29th February 2004, 07:11 PM   #3
andy_c is offline andy_c  United States
Join Date: Apr 2003
Default Re: LM3x7 HV regulating.

Originally posted by w00t
I would like to know how to regulate a HV/HT line with the LM3x7 series.(...)
Hi w00t,

See the Linear Technology app note 2 http://www.linear.com/pdf/an2.pdf. Figure 11 and the text above it shows how to use the LT317 in a high-voltage configuration.
  Reply With Quote
Old 29th February 2004, 09:42 PM   #4
djmiddelkoop is offline djmiddelkoop  Netherlands
diyAudio Member
djmiddelkoop's Avatar
Join Date: Feb 2003
Location: Noord-Holland
Just to give an example :

The transistor takes care of the input voltage which otherwise is out of scale, read destroy the 317.
The voltage across the 317 is determined by the zener minus the Vbe of the transistor = approx. 6V.

I have used this many times and it works very well as long as the output is not shorted to ground.

Attached Images
File Type: gif lm317.gif (7.7 KB, 91 views)
“Information is not knowledge Knowledge is not wisdom
Wisdom is not truth Truth is not beauty Beauty is not love Love is not music Music is THE BEST”
  Reply With Quote


LM3x7 HV regulating.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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Improving the LM3x7 regulator circuit Geoff Power Supplies 206 28th December 2016 08:27 PM
Regulated PS with LM3X7 ? kacernator Solid State 0 13th March 2009 04:04 PM
LM3X7 Supply zei Power Supplies 25 23rd December 2007 06:52 AM
Heater Supply using LM3X7 current source Tomo Tubes / Valves 10 1st June 2005 11:38 AM
LM3x7 Datasheet Error? richie00boy Parts 5 7th July 2004 08:32 PM

New To Site? Need Help?

All times are GMT. The time now is 07:11 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio