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10th Feb 2021, 10:59 am | #1 |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Neon EHT Indicator wand.
Neon Indicator wand useful item, quick checking for eht, lcd backlight inverter safely, all you need is a 5mm dowel I used a lolly stick neon bulb and a piece of shrink sleeve,
cut a angle with junior hacksaw fit neon in groove and finish with shrink sleeve. Keep in pencil drawer one day it may be useful. John |
10th Feb 2021, 12:17 pm | #2 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,105
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Re: Neon EHT Indicator wand.
In principle fine, but don't try it on the mains
Wouldn't it be worth adding a 220k resistor in series, it will still light up nice and bright with EHT
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10th Feb 2021, 1:13 pm | #3 | |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Neon EHT Indicator wand.
Quote:
John |
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10th Feb 2021, 1:19 pm | #4 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,733
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Re: Neon EHT Indicator wand.
This was a technique recommended in older Tek oscilloscope manuals for checking the high voltage oscillator was running, the neon was placed against the glass envelope of the oscillator valve, though in the picture it is held without a stick.
David Last edited by factory; 10th Feb 2021 at 1:25 pm. |
10th Feb 2021, 1:36 pm | #5 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Neon EHT Indicator wand.
Had one in my tool kit, well worth it for checking around the EHT in TV sets.
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Frank |
10th Feb 2021, 1:41 pm | #6 |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Neon EHT Indicator wand.
I know it is an old technique, I was just using odds and ends lying around, I used it to detect if inverter was working on laptop, did not fancy holding neon by the wires, seeing what happened to an apprentice years ago when he stuck a neon screwdriver into a insectocuter to check it was working, his reaction showed everyone in the room it was.
John |
10th Feb 2021, 1:47 pm | #7 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,105
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Re: Neon EHT Indicator wand.
You're saying it works on DC?
Intriguing, what sort of minimum voltage do you need to light a disconnected neon?
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10th Feb 2021, 1:47 pm | #8 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Neon EHT Indicator wand.
As long as it didn't become an apprenticocuter!
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10th Feb 2021, 4:08 pm | #9 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,998
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Re: Neon EHT Indicator wand.
I used to have a similar "Dipstick" for testing whether there was RF present in transmitter/ATU 'tank' circuits - mine used a NE-2 type Neon with its legs extended by a couple of inches of wire, fitted into the end of a clear Polystyrene tube about two feet long.
MF/HF power made it glow orangey; VHF gave an impressive purple! |
10th Feb 2021, 4:28 pm | #10 |
Heptode
Join Date: Nov 2009
Location: Scarborough, North Yorkshire, UK.
Posts: 510
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Re: Neon EHT Indicator wand.
I'm sure readers will already know, a simple way to test on a micro wave cooker is to mount a neon with both lead bent outwards (antenna) using some Blue tack and a glass of water. As the plate rotates the neon flashes on and off
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10th Feb 2021, 7:26 pm | #11 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,859
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Re: Neon EHT Indicator wand.
Used to tape just the glass neon on tip of vhf 2 way radio aerials on my works van. Nice purple glow.
Toy, really, soon fell off and never replaced. Rob
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10th Feb 2021, 8:04 pm | #12 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Neon EHT Indicator wand.
Surely, a purple glow requires argon. Neon gives an orangy pink.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
10th Feb 2021, 8:28 pm | #13 | |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,998
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Re: Neon EHT Indicator wand.
Quote:
You'll get purpleness. Trust me on this. In times-past the colour-of-glow from your neon-dipstick was a reliable indication of whether the parasitic-oscillations in the amplifier-you-were-debugging were VHF or LF. |
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10th Feb 2021, 10:31 pm | #14 |
Heptode
Join Date: Dec 2003
Location: South Yorkshire, UK.
Posts: 900
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Re: Neon EHT Indicator wand.
This looks a fun little project I like gimmicks like this. I remember back in the day it was possible to buy some impressively large neon lamps. The little modern ones do look a bit sad. Thanks for posting.
Regards Chris
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10th Feb 2021, 11:08 pm | #15 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Neon EHT Indicator wand.
Thank you for enlightening me on this.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |