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 #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
Tried it a few years back with 5mm clear super-bright RED LEDs. Sometimes if you fry the inside chip in a certain way it will create a rather stable little spark gap sealed inside the plastic (kind of neat for a miniature electrical noise source.)
For RF indicators simply add a LED across a few turns of a coil antenna. (For old cell phones it is about 2 to 3 turns of the GSM antenna IIRC)
I have burnt out LEDs doing this in the past but they "still light"!! In fact, a "burnt out" LED lights fine under high voltage. So it may seem like the LEDs work but if you go to power them up normally they might look dead. However, if the LED still "works" who cares The fancy high brightness and "modern" LEDs often tend to be far more fragile.
I did look at the LM3914 circuit today but the LM3914 starts to pull off at 20kHz and is totally gone at 50kHz. If one wants to do a linear bar graph, it would probably have to be made out of discrete comparators and such. I might still look into that since it would be so cool
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
I am in the process of planning a 10 stage bipolar current meter with the bells and whistles. In this process I tested a red LED and a Blue LED for reverse breakdown. Red forward voltage was 1.5V at 20mA.
So it seems that the red LED acts as a zener with a soft turn on. The blue seemed to blow before any significant current was taken. Hence as determined experimentally, the red LEDs are the best to take HV abuse.
Green LED's went to about 22V before blowing. Old style red LED's were OK with Zener action at about 23V.
Photo 1 Old style red LED unprotected. Photo 2 Red LED 3W Lumiled. Reverse protected with standard red LED.
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
All this is hard on LED's which don't last long. LED's can die by degrees as below. I seem to have blown a lot lately trying to get a current meter going. It goes but eventually the LED's die.
Photo 1 shows a normal red LED driven by 6 VAC via a 1 k resistor plus antiparallel green and blue LEDs which is my wired test setup (very handy). Note the LED die (light emitting square in the centre of the LED. Only the blue LED lights as current only passes in one direction. Photo 2 shows a partially dead LED where the square die has a non functioning area. In addition the LED is not bright and it conducts in both directions as both green and blue LED's light up. Photo 3 shows a partially dead LED where the square die is still normal but the LED is not bright and it also conducts in both directions as both green and blue LED's light up.
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.
LED's for spark monitoring
The fancy high brightness and "modern" LEDs often tend to be far more fragile.
