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.
When this circuit was created, how could they calculate/know that the transistor would not burn? If I remove the Secondary, how much current would pass through those three thick loops of copper wire connecting the collector and emitter of the 2222A transistor?
2222A transistors can handle 800mA of collector current.
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
Tarakan2 By knowing a lot more than the diagram gives transformer specs are the most important here and the diagram doesn't give a hint a bit like the link you provide in this post --a bit troll like if you ask me!!!!!
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
If I remove the Secondary, how much current would pass through those three thick loops of copper wire connecting the collector and emitter of the 2222A transistor?
that is a very difficult question to answer precisely,
. assume for now that the 2222A has a current gain of 100 . the voltage across the 22k resistor will be 9 V - 0.7 V (battery voltage - base voltage), about 8.3 V . the base current is 8.3 V / 22 K = 0.377 mA, so the collector current is 100 x 0.377 = 37.7 mA . the collector power dissipation of the 2222A transistor is 9 V x 37.7 mA = 344 mW ... enough to make the transistor really hot, about 110 C above ambient.
that is the simple theory, in practice; none of the constants are constant none of the parameters are straight-line when graphed the battery voltage decreases as you draw more current the base-emitter voltage increases as the current increases the base-emitter voltage decreases as the temperature increases the gain of the transistor changes with temperature and current transistors can actually get hot enough to burn your fingers before they fail ......
P.S. the 2N2222A is electrically the same as the 2N2219A which can dissipate more heat almost any circuit that uses a 2N2222A can use a 2N2219A instead this circuit can use almost any npn transistor with good gain.bandwidth
Registered Member #3859
Joined: Sun May 01 2011, 03:47PM
Location:
Posts: 179
johnf wrote ...
Tarakan2 By knowing a lot more than the diagram gives transformer specs are the most important here and the diagram doesn't give a hint a bit like the link you provide in this post --a bit troll like if you ask me!!!!!
I am not a troll, Often transformers are under-documented in circuits and their descriptions. This is common in hobby electronics unfortunately.
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
Sorry Tarakan about the troll comment but
"Welcome, welcome, welcome. I dont post things that I havent verified myself."
doesn't make sense.
However a design unless stating all parameters for the transformer is going to be a mystery. you need to know the windings (turns, wire diameter),the core type, the winding sense, the winding order, the primary inductance, the secondary inductance, and the leakage inductance. With all of this you are in with a chance of recreating what has been posted unless you are an EE with a lot of time on his hands who can calculate a near approximation from the circuit you posted.
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.
How does the primary limit current to keep transistor from burning in this circuit?
