Benchtop PS - Page 3 - 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 6th December 2005, 01:57 PM   #21
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
You know, every now and again I find myself designing a Rube Goldberg circuit. The skill is getting rid of unnecessary elements while maintaining performance.

For higher power high voltage, I just use a variac with a higher voltage supply (using SS rectifiers). Expecting one supply to do it all is unreasonable. That's a good way to get to know Mr Goldberg.

-Chris
  Reply With Quote
Old 6th December 2005, 03:19 PM   #22
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Default Re: Re: Re: Re: DIY Benchtop PS

Quote:
Originally posted by jackinnj
you can use an LM10 -- not a particularly fast chip but it can be used where a floating reference is required. You can always use zener's to float the opamp -- just make sure that there is a diode to protect it from an overvoltage situation (i.e. you have to clamp the inputs).
Yes, but you still have to provide current for the zeners and OPamp, and that's where the problem is - in a situation where you have to drop from zero to seevral hundred volts depending on voltage setting, at some 10mA or so, you are looking at a lot of excess heat, and possibly current sources capable of 600V or so voltage drop. Zeners do not make voltage, just offer a constant voltage drop.

I have attached a basic schematic of what I had in mind - it is overly simplified, shows no protection components and frequency compensation, etc. A few notes:
The top CT winding can of course be a separate transformer, and need not be CT, current draw is small and largely constant so a single winding secondary with oposed halfwave rectification (to get a positive and negative tracking supply) will work just fine here. If it is a winding on the same transformer, at least 1kV of isolation is required, preferably more.
RI and RV set current and voltage respectively. They actually set up reference voltages, and the stability and quality of said is only as good as the regulators in the tracking supply. A separate zener or similar reference could be put in parallel with RI and entirely replace RV (which would make R2 variable to regulate output voltage, IMHO this is the better solution anyway).
Although low offset OPamps are not mandatory, good offset stability helps, as do FET inputs. Good output drive is a big plus here, even though the circuit will not likely be very fast, youa re trying to drive some nanofarads of gate capacitance of the MOSFET.
Frequency comp capacitors and zener clamps for OPamp inputs and MOSFET gate are mandatory in a real implementation.
Attached Images
File Type: gif psu.gif (12.7 KB, 464 views)
  Reply With Quote
Old 7th December 2005, 02:35 AM   #23
diyAudio Member
 
userguide's Avatar
 
Join Date: Jun 2004
Location: +48 6' 6.29", -77 52' 50.99"
Variable PS based on the Supertex LR8 regulator:

http://antiqueradios.com/forums/Foru...ML/002132.html
http://antiqueradios.com/photogallery/LR8N3PSq.gif


and
another one:
http://www.roehrenkramladen.de/hboexp3/hboexp3.htm
  Reply With Quote
Old 8th January 2006, 01:55 PM   #24
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
Originally posted by userguide
Variable PS based on the Supertex LR8 regulator:

http://antiqueradios.com/forums/Foru...ML/002132.html
http://antiqueradios.com/photogallery/LR8N3PSq.gif


and
another one:
http://www.roehrenkramladen.de/hboexp3/hboexp3.htm
Took that one step further -- the Vactrol opto-isolated variable resistor is used as the gain setting tool, the other opto-isolator and servo is isolates the HV supply from the data acquisition card and computer. If you've ever fried a mother board you'll know why.

The LR8N3 will provide about 20 ma max base drive -- so this will work with a MJE3439 or BU208a, but a Darlington configuration would be one step better. I bought a bunch of LR8N3's from Mouser, so if anyone needs 'em go to my website.
Click the image to open in full size.
  Reply With Quote
Old 8th January 2006, 03:48 PM   #25
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
The best bar none is the Fluke 407.
I saw this statement when it was printed, then I saw the Fluke 407-D on Ebay go for $25 but I missed it. Then another Fluke 407-D showed up on Ebay for $25. I bid, no one else did, I got it for $25.

When It arrived, I tested it and it works. Took it apart just to see what is inside. This thing is built like a tank. 3X 807's for pass tubes, 2 large PC boards with several tubes on each. Monster transformer! The regulation is excellent and it goes up to 550 volts!
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 8th January 2006, 04:03 PM   #26
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi tubelab,
You can do some damage with that!! Nice score! How much was the shipping?

-Chris
  Reply With Quote
Old 8th January 2006, 04:09 PM   #27
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Shipping was a flat rate $45. I believe the particular seller is making some good money on shipping, but at least in my case he had to ship it from California to Florida.

Even so $70 was a good deal for this power supply since people are paying $100 for Heathkit power supplies.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 8th January 2006, 09:30 PM   #28
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Well worth it tubelab! You must be feeling all warm and fuzzy with the new gear.

-Chris
  Reply With Quote
Old 8th January 2006, 10:39 PM   #29
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Warm, yes it gets warm in here when I turn too much stuff on. Fuzzy, yeah some of my amps sound like that.

Actually I needed more voltage than my Knight can put out. The home made HV power supply is just too physically large to fit my small bench, so I am rebuilding it. I got a surplus 1500 volt transformer. I will feed it with a 4 amp variac and follow it with a SS bridge and filter for a simple 0 to 1800 volt bench supply. I should be able to fit this into a small box.

I will keep the Fluke, the Knight, the new HV supply, and my two SS low voltage supplies for filaments op-amps and other SS experiments. I have a 0 to 20 volt, 50 amp monster under the bench for simulated car battery experiments. You can never have too many power supplies, I would have more if I had the space for them.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 25th January 2006, 02:53 AM   #30
sklimek is offline sklimek  United States
diyAudio Member
 
sklimek's Avatar
 
Join Date: Oct 2004
Location: Arizona badlands
It seemed for the longest time I could not find a power supply for my tube project and then BAM they started presenting themselves. I ended up w/ two; the first one is a Lambda model 71, beautiful in both condition and performance. Two weeks later a Hewlett Packard 712B became available on Ebay and I couldnt resist. 45.00 dollars plus 45.00 for shipping, both are 500V @ 200mA w/ a panel variac for the HV control. The 712B manual states that an additional 300 volts (800 total) can be available by connecting the load across the +HV and -300V 50mA bias supply. Both of these power supplies are 50+ years old and all that was needed were two binding post replacements for the 712B. The combined weight of both is 120 lbs. Unbelievable how well these boat anchors were made.

Im sure this is a long shot but Id be willing to trade one of them for a HP distortion analyzer or Tek 465 scope if anyone is interested.

Stan
  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
HP 3478A - benchtop DMM (calibrated) n_maher Swap Meet 2 5th November 2008 04:34 PM
Guidance for a benchtop power supply for car amp chemhaz Car Audio 3 14th June 2008 12:53 AM
DIY Benchtop PSU TroelsM Power Supplies 18 9th October 2007 02:31 PM
Wiring car amp to a benchtop power supply bans27 Everything Else 5 15th March 2006 08:30 AM
DIY benchtop power alecwek Parts 12 18th August 2004 11:33 AM


New To Site? Need Help?

All times are GMT. The time now is 12:48 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