If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2422
Joined: Tue Oct 06 2009, 02:41AM
Location:
Posts: 85
So for a project I'm working on I need an adjustable dc supply between about 20 and 150 volts at 5 amps. I can't afford a variac or fancy bench supply, so I went with DIY. But I've never made something like this before, so I thought I'd post up here so the experts can tell me what's wrong with it before I blow up all my fets.
BTW, because Multisim doesn't have any high-side drivers, that's what the random objects labeled LT1910 are. The pins are V+, GATE, GND, and IN. This should be pretty self explanatory. EDIT: Oh yeah, the 555 has that diode so the pot adjusts the duty cycle from 0% to 100% without changing the frequency, which is 20kHz. I don't know if that's obvious or not.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
The adjustment potentiometer is connected to the positive side of the rectified line via a 9v battery hence it is also 'live'. I would not recommend it !
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
this needs some kind of feedback otherwise the no-load voltage will be 170V. The UC384x chip is good for supplies like this. The 20uF cap is too small, for 5 amp output you will need at least 1000uF (more likely 2200uF) with a soft-start circuit. Don't know about the gate drivers, I'm not familiar with that type.
PS. I'd get a 200volt MOSFET (IRFP260 comes to mind) and not use two in series with complicated gate drive.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
yeah, it needs isolation.
However, an "old school" hack is to obtain a JFET and linear optocoupler (the difference is that it behaves like a BJT) and use the optocoupler to control the JFET gate voltage.
if you are really short of cash you can even make a homemade equivalent using a surplus can transistor (BFY51?) and a pair of yellow LEDs back to back, which if correctly biased will control the current almost as well as if the transistor was driven directly.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Standard practice according to the IEEE regulations is to isolate any mains potential points with double insulation. So even if the knob was non conducting, if due to a fault the inner shaft was to come in contact with live mains in the event of the metal wiper coming loose, a dangerous situation could arise.
Better to use an optoisolator here, at least then the chances of it going badly wrong can be minimised. (case in point, every SMPS I've seen has one or more to keep the system stable)
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Don't forget that the negative is also live, so whatever is powered by this supply will also be LIVE. If that's ok then please humour me by putting a warning on any circuit diagrams that you put on the net, better to warn any may copy it.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
0-170V adjustable SMPS (is this going to explode?)
