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 #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Bjørn wrote ...
Sensors like have a dynamic range of more than a million to one and the response is linear.
TSL230 looks as though it could be very interesting to try out as an indirect detector with a scintillator, and perhaps as a direct detector too, at an affordable price.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
amazingly cool idea Proud Mary, i will try this asap.
A little "gotcha", superglue sets by absorbing moisture so once the setup is complete its worth carefully drying it in an oven at 50C or so before final encapsulation to ensure that the sensor doesen't fail over time (don't ask how i found that out!!!)
An idea for a small voltage source, get one of those HV825 EL inverter IC's and connect the outputs to a multiplier. They draw very low current and can be set up to only turn on when the stored voltage begins to drop.
I might have tried this but ran out of IC's due to flaky EL wire.
Another idea is to use a very low power negative resistance oscillator such as the J310+BC212 or 2N3819+PN3820 etc, these can draw next to no current yet the resonant circuit peak to peak voltage can exceed 200V.
As for lightproof end windows, carefully split and sanded down pyrolytic graphite works (confirmed with CMOS sensor) and not too expensive at around £9 for enough to make a couple dozen devices. -A
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Conundrum wrote ...
amazingly cool idea Proud Mary, i will try this asap.
A little "gotcha", superglue sets by absorbing moisture so once the setup is complete its worth carefully drying it in an oven at 50C or so before final encapsulation to ensure that the sensor doesen't fail over time (don't ask how i found that out!!!)
An idea for a small voltage source, get one of those HV825 EL inverter IC's and connect the outputs to a multiplier. They draw very low current and can be set up to only turn on when the stored voltage begins to drop.
I might have tried this but ran out of IC's due to flaky EL wire.
Another idea is to use a very low power negative resistance oscillator such as the J310+BC212 or 2N3819+PN3820 etc, these can draw next to no current yet the resonant circuit peak to peak voltage can exceed 200V.
As for lightproof end windows, carefully split and sanded down pyrolytic graphite works (confirmed with CMOS sensor) and not too expensive at around £9 for enough to make a couple dozen devices. -A
I think as long as folk don't expect these simple devices to work at the µGy level of background counting and small test sources and understand that we're talking of X-ray concentration - photon fluence - of perhaps 10E11 photons/cm2/sec no one will be dissapointed.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Just a thought but those cheap "TV" shaped Fifty50 digital picture frames use a 1MB 8 pin serial flash memory. Thats a lot of space and more than adequate to store radiation data directly as a bitmap by writing to the unused flash areas. Readback is as simple as plugging into the PC and putting into "usb" mode.
Also could use them as a very cheap spinthariscope-clone, by copying bitmap data from a suitable CMOS camera or optical mouse sensor, see my earlier posts re. pyrolytic graphite used as a light shield. Some of the screens on these picture frames are very high resolution 128*128 N*k*a knock-off identical to phone screens.
also if anyone needs geiger tubes,
Has anyone tried sanding or otherwise CAREFULLY dissolving away the overlying plastic on the intensifier screens to see if they then detect alpha and beta? my thought is that if this works then they could be used with the previously mentioned CMOS camera to make a truly miniscule radiation counter/logger.
EDIT:- tried building one of the sensors and it seems to work as far as the sensitivity to light (tried UV which generated sizeable pulses even through 3mm of graphite/tyre repair compound)
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
A Minor Hiccough
I've put away my Pull Me - I'm a Little Christmas Cracker! T-shirt till next year, and set about the sober business of providing some calibration base lines for other builders.
I rarely find anything sufficiently interesting >30keV, but I know that I'm more or less alone with these long, soft waves - except at times for Plazmatron - so a higher energy calibration is needed if the measureless majority are to benefit from the contraption.
I fired up Hekla - 70kV/3mA - but no sooner had the heater delay period ended, than the alarm went off, with auto shut-down.
The fault proved to be a mGy sized leak caused by distortion of the lead gasket interface between the tube housing flange and the apex of the beam shielding pyramid, as these pictures make clear.
It will be a week or ten days before I can find time to re-assemble Hekla, and provide the 70keV Ohm-per-Gy data needed for others to use this simple direct reading dosimeter.
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.
Christmas Cracker X-Ray Dosimeter
