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.
so im looking to make a remote controlled spud gun. im using a wireless doorbell and the LED in the receiver unit is connected to a transistor as follows. then a disposable camera flash is hooked to go off through the relay
and i have a few questions
and can i also without using the relay and the 9v battery just connect the camera's flash trigger terminals between the transistor's collector and emitter?(the trigger terminals have a pd of around 83v) will it fry the transistor if i do it this way?
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
I do not think you need such a powerful transistor there, the relay contacts should take a few hundred ma max. Use a PN2222 or similar. I would use the relay, and not just put the transistor across the trigger terminals. You probably don't need the resistor in question, if the doorknob circuit drove led's directly, it will be current limited. I would probably use something like a 1k resistor to be safe tho.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Transistors like the 3055 has a a very low hFE (current gain) and needs a significant base current to reach a high collector-emitter current so 20 mA base current might be too low.
A SCR might be useful for direct connections to the trigger terminals depending on the design of the circuit, I have had good luck that way.
You need a reliable safety lock, otherwise you will end up shooting yourself in the face when it triggers by itself (sooner or later it will).
Transistors like the 3055 has a a very low hFE (current gain) and needs a significant base current to reach a high collector-emitter current so 20 mA base current might be too low.
A SCR might be useful for direct connections to the trigger terminals depending on the design of the circuit, I have had good luck that way.
You need a reliable safety lock, otherwise you will end up shooting yourself in the face when it triggers by itself (sooner or later it will).
how could it trigger by itself? as in the transmitter and receiver are code locked
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
There are at least 10 ways it could trigger by itself when it is completed. Each way has an unknown statistical chance to happen. Since you have no way of knowing how safe it is; assuming that it is not safe is the only way to be safe.
The doorbell design can be pretty bad, some such coded receivers can fail in a second or less if they recieve the right noise signal.
I have had several such transistor fail short circuit from static electricity. For you circuit to be safe it must not trigger if a transistor or a chip fails.
There are at least 10 ways it could trigger by itself when it is completed. Each way has an unknown statistical chance to happen. Since you have no way of knowing how safe it is; assuming that it is not safe is the only way to be safe.
The doorbell design can be pretty bad, some such coded receivers can fail in a second or less if they recieve the right noise signal.
I have had several such transistor fail short circuit from static electricity. For you circuit to be safe it must not trigger if a transistor or a chip fails.
you might have somethign there man.
i connected everything as above. without the resistor. and the led from the doorbell in series with the transistor(good thing i did read below)
a little problem. i first tested it by hooking up my signal injector between the collector and emitter and then triggering. then it worked as planned.(the signal injector sounded when i pressed the remote)
but when i stopped the remote with the signal injector still connected the led was still very dimly lit and when i removed the injector the led stopped lighitng. i checked to see if there were any shorts but none.
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 this transistor arrangement(noob question)
