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 #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Conundrum wrote ...
its a way to get the effect of a larger inductor with fewer windings... hope this helps, -A
Sorry, but I have too hard time imagining how would a ferrite magnet have a positive effect on Q. A ferrite rod likely would since it would increase inductance, but I don't see what a magnet would do except cause a huge hysteresis loss.
Registered Member #3307
Joined: Tue Oct 12 2010, 12:18PM
Location:
Posts: 4
Hello Marko!!
You did a graet work, with this project. I have som issue, i hope You could explain to me.
I don't really understand how of the modified royer oscillator works. Is there a feedback that provides the frequency of the oscilator? Just like deathell i tried to simulate the circut witch PSpice and Multisim, but it faild. What is the type of the transmitting wave? Sine wave? I read abaut the royer oscilator it gives a square-wave signal.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
hanys wrote ...
Hello Marko!!
You did a graet work, with this project. I have som issue, i hope You could explain to me.
I don't really understand how of the modified royer oscillator works. Is there a feedback that provides the frequency of the oscilator? Just like deathell i tried to simulate the circut witch PSpice and Multisim, but it faild. What is the type of the transmitting wave? Sine wave? I read abaut the royer oscilator it gives a square-wave signal.
I'll be grateful if someone solve the issue.
Thaks & Regards
Hi hanya,
I've never succeeded simulating a royer oscillator either - I rather spent time getting it to work in real life :P
Yes, there is a feedback in the circuit, and it's provided by the diodes going between the mosfet gates and the tank.
It's true that mosfets in this circuit operate in nonlinear range, with their gate voltages being mostly square wave - but the output tank chokes out all the harmonics apart from it's fundamental frequency and hence you see nearly perfect sine wave on the output.
Registered Member #3307
Joined: Tue Oct 12 2010, 12:18PM
Location:
Posts: 4
Hallo Marko
By the output tank chokes you mean the RFChokes? So correckt me if i am wrong. The MOSFET transistors switch the RF chokes, so the current flows through the first choke, and then the second. The core in the choke stores the energy, and the on MOS turne off. In the time when the first MOS is off and second MOS does not turn on yet, the choke gives the current to the LC tank. I can't figure out, how the diodes provides the feedback. could you explain it? regards
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
hanys wrote ...
Hallo Marko
By the output tank chokes you mean the RFChokes? So correckt me if i am wrong. The MOSFET transistors switch the RF chokes, so the current flows through the first choke, and then the second. The core in the choke stores the energy, and the on MOS turne off. In the time when the first MOS is off and second MOS does not turn on yet, the choke gives the current to the LC tank. I can't figure out, how the diodes provides the feedback. could you explain it? regards
No, I mean the tank circuit will dampen out all the harmonics of the input current apart from the fundamental one. Hence you get clean sine wave output.
Firstly, both mosfets are being drive on by pullup resistors - but this condition is metastable and always results in one mosfet turning on sooner, after which another one is shut off since it's gate voltage is driven to zero through the diode. The voltage on the tank circuit will ring up and , and at some point it will reverse causing the gate vltage of the ON mosfet to drop to zero - then the mosfets switch places.
The chokes in this case act as current sources - despite they seem to carry mostly DC, the current will be limited to a constant value once the voltage across them becomes pure AC.
You can make this circuit work at low power with current sources made of LM317's, at arbitrarily low frequencies if you wish. I made one drive a DC motor with pendulum attached as a surogate for a very low frequency parallel LC tank.
Registered Member #3354
Joined: Sun Oct 24 2010, 09:48AM
Location: Tulkarm-Palestine
Posts: 10
Hello Marko!!
i'm very interist in your work .. i tried to test your circuit before implement it in PCB by connect it in the white board .. but I faild !! source current was only .2 A !! No current pass the loop, because voltages across the cap =0 (3.4-3.4)!! realy I can't understand what is the problem .. I'm sure that the connections and parts are same with that you used!!
then I tried to simulate it using workbench and I have almost pure sine-wave with 50 Vp but with speed damping to becom zero (what is that mean??)!!
I don't know what should I do!! Do you have any advice for me??
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi,
If you connected your tank caps and your loop over the breadboard, that is probably the cause of the problem. Breadboard is by no way an adequate connection for 20amps of RF and caps should really be soldered to the loop with as short connections as possible.
Other than that, make sure you're using polypropylene caps, and not ceramic or polyester ones.
Registered Member #3354
Joined: Sun Oct 24 2010, 09:48AM
Location: Tulkarm-Palestine
Posts: 10
Marko wrote ...
Hi,
If you connected your tank caps and your loop over the breadboard, that is probably the cause of the problem. Breadboard is by no way an adequate connection for 20amps of RF and caps should really be soldered to the loop with as short connections as possible.
Other than that, make sure you're using polypropylene caps, and not ceramic or polyester ones.
Marko
thank you for the quick reply... I have prepared The PCB layout and i will start soldering the components soon
first i have some questions.. the relay you used .. you said that to overcome slow rising of the voltage!! Why will that be?? and how could the relay help while the it will be activated directly when it connected to the power supply?? the output voltage is pi*input voltage .. is this is a formula?? from where you get this?? The RFC working as current source .. would you give me more explination how it become like that?? In my simulation with workbench the frequency was only 314 KHz!!
again i repeat my great thanks for you and forgive me for my bad english Maher .. Electric eng
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.
Miniature wireless power demonstrator
