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.
which uses the L6506 as a PWM controller. I decided to use "phase chopping" instead of enable chopping as defined in the datasheet.
My circuit design looks like this:
It features two simple R2R DACs and two separate channels for 2 motors.
The reference voltages are slowly being ramped up from 0mV to 150mV but the average voltage drop across the shunt is 87mV when a motor is attached running at about 0.9A (12V). I've checked the circuit over and over again, I've measured the potential differences across the board, I've attached an incadescent lamp in series to a storage choke to test a current regulator setup but all i get is the following:
the 0..100% regulation appears to happen within Vref= 20..30mV, the shunt voltage rises from 2mV to 227mV (corresponding to 2.3A). I've already tried to blame the L6506, replacing it with a new one in a DIL socket, but the behaviour stays the same. There are bypass caps everywhere and the power side is stabilized with 2000µF electrolytic low ESR caps. I feel completely stupid trying to debug this circuit. Please help
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
After testing the L6506 at different clock speeds on a breadboard, the current limiting comparator appears to work fine. I chose a 0.1 Ohm 2W shunt for a 0-4A current range. Could it be that the voltages (20-50mV) are just too low for stable operation in a noisy environment? Do I need pulse-to-pulse current limiting after all?
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
closure:
I can't believe how stupid this is. The mistake I made is too simple to be true. Have a look at the schematic for your entertainment. You can now see the controller run in this video:
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.
Need help with PWM motor control (using L6506+L6203)
