UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Closed Thread
 
Thread Tools
Old 17th Mar 2023, 10:32 pm   #1
Cruisin Marine
Heptode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
Default Step up transformer from 9 to 575 volts for a Geiger tube.

Am in the process of building a Geiger counter. I am initially planning on using a 555 at something like 100 kHz, driving a transistor and a step up transformer to increase a say 7 volt DC regulated supply from a pp3 battery supply source.
Anything from say 150 volts AC at bugga' all current will be fine 'cos I can use voltage multipliers easily on the secondary.
Any ideas greatly appreciated.
Thanks
PS the title of the thread needs editing, I typed too fast and posted- ty.
__________________
"Behind every crowd, there's a silver Moonshine"
Cruisin Marine is offline  
Old 17th Mar 2023, 10:46 pm   #2
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
Default Re: foStep up transformer from 9v to 575 volts r a Geiger tube

Look up "Boost converter" and use a proper SMPS drive chip to do current mode control, like LM5022. This avoids a lot of troubles of trying to use 555 and adding more circuits to fix shortcomings.

Boost = flyback architecture means you don't need so extreme a turns ratio and you also get regulation.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 17th Mar 2023, 11:13 pm   #3
Terry_VK5TM
Nonode
 
Terry_VK5TM's Avatar
 
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
Default Re: foStep up transformer from 9v to 575 volts r a Geiger tube

"If" you can find one of those old disposable film cameras, the flash unit out of them can be easily modified for use and as a bonus, works off a 1.5V battery.
__________________
Terry VK5TM
https://www.vk5tm.com/
Terry_VK5TM is offline  
Old 19th Mar 2023, 8:36 pm   #4
Cruisin Marine
Heptode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Look up "Boost converter" and use a proper SMPS drive chip to do current mode control, like LM5022. This avoids a lot of troubles of trying to use 555 and adding more circuits to fix shortcomings.

Boost = flyback architecture means you don't need so extreme a turns ratio and you also get regulation.

David


Thanks, I am investigating that route. It is new tech for me, I have researched on the net and see endless info. much of which is a bit iffy, but I shall have to bite the bullet and try it.
I get the jist of how it works using PWM, but like everything new, go slowly and learn, those chips are not overly cheap so will try to avoid any mistakes.

The Geiger Muller tube needs a set voltage to work efficiently, within the plateau or Geiger region, this is all new ground for me- but great fun.

Re the 555 idea, The chances of getting a bias transformer from a reel-to-reel bias oscillator or similar seem very slim anyway.
__________________
"Behind every crowd, there's a silver Moonshine"

Last edited by Cruisin Marine; 19th Mar 2023 at 8:58 pm.
Cruisin Marine is offline  
Old 19th Mar 2023, 10:02 pm   #5
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Hi, plenty of pot cores available on ebay. Ideally get one with a 4 section bobbin to reduce self capacitance and give better insulation
A 30mm dia or greater type should give sufficient space for your windings

Ed
Ed_Dinning is offline  
Old 19th Mar 2023, 10:25 pm   #6
Cruisin Marine
Heptode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Can you please link to a relevant one please Ed?
Thanks
__________________
"Behind every crowd, there's a silver Moonshine"
Cruisin Marine is offline  
Old 19th Mar 2023, 10:37 pm   #7
DrStrangelove
Banned
 
Join Date: Jan 2023
Location: Neath, Port Talbot, Wales, UK.
Posts: 286
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

I bought a geiger counter kit from Bull Electrical back in the mists of time.

It uses a transistor multivibrator driving some iron cored transformer followed by a voltage multiplier.

The geiger tube is tiny and windowless so if it clicks you know something quite significant hit it.

It detects some uranium glass quite well and the I-131 treatment my late mother had sent it crazy even through a wall.

The tube runs at about 350 - 400V.

On the other hand, the GM4 geiger tube requires 1500V plus. It worked quite well connected to a Tek curve tracer about 40 years ago. The pulses were quite visible on the screen.
DrStrangelove is offline  
Old 20th Mar 2023, 12:38 am   #8
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

A few hints:

Be careful about internet advice. In a fair proportion of cases it amounts to the blind leading the blind. Not all, but you almost need enough knowledge to be able to do the job yourself in order to spot the clueless.

National Semiconductor (now part of Texas Instruments) and Linear Technology inc (Now part of Analog Devices inc) Wrote excellent applications notes on these sorts of circuits. They take new users by the hand and lead gently. The LT ones , many of them were written by the legendary Jim Williams are worth reading even if you aren't using their parts. Often, inductors may be available from Coil Craft inc. They have a place near Cumbernald and if contacted via their website, are known to give the occasional (one-off) part to hobbyists as a free sample. Their parts are excellent, their service is excellent, but they are also friendly and encouraging.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 20th Mar 2023, 11:05 am   #9
Hengist
Triode
 
Join Date: Feb 2014
Location: London, UK.
Posts: 20
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

I've put together a geiger counter twice. The first time I used a reversed 9V mains transformer followed by a voltage doubler as in this video:
https://www.youtube.com/watch?v=8zM1HG9Agzk
The second time I used a reversed AF driver transformer from an old transistor radio followed by a 7 stage Cockcroft-Walton multiplier. The frequency applied to the transformer was around 15 kHz in the second case.

Tim
__________________
Regards,
Tim
Hengist is offline  
Old 20th Mar 2023, 3:13 pm   #10
Tim
Dekatron
 
Tim's Avatar
 
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 3,301
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

You might be able to use the gubbins from one of those fly killer tennis racquet things they sell in the pound shops. Because I’m a nerd I measured the voltage of one for curiosity and found it was several hundred volts.
__________________
"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."
Tim is offline  
Old 20th Mar 2023, 8:05 pm   #11
Cruisin Marine
Heptode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

I got a very cheap camera flash unit made by Jessops today in a charity shop. It has a transformer driven by two 2SA1242 PNP devices, I need to do some tracing to see how they are driven. It works fine (or did before I dismantled it all). Hopefully I am sorted now.
Thanks to all, especially Tim for the interesting video, nice to know which sources can be used to test the Geiger.
I wonder if that Uranium glass or porcelain is still easily available?
__________________
"Behind every crowd, there's a silver Moonshine"

Last edited by Cruisin Marine; 20th Mar 2023 at 8:15 pm.
Cruisin Marine is offline  
Old 20th Mar 2023, 9:26 pm   #12
broadgage
Nonode
 
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

A useful test source is an old stock pressure lamp mantle. Newer production might be non radioactive but older ones contain radioactive thorium.

"Uranium glass" has come to mean a style of glassware that may not contain any actual uranium. Genuine antique uranium glass can be a useful test source, but modern production may not be.
broadgage is offline  
Old 20th Mar 2023, 10:09 pm   #13
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Hi Presently away from home, but try looking for Pot cores on ebay. Ideally you want a new one, but cheap older ones can be stripped. Mullard made them in a variety of sizes up to 45mm and on a range od ue grades (higher ue/ lower turns needed)
An inductor core normally has an airgap(possibly with an adjuster); a transformer core is ungapped (but can easily be gapped).
Transformer types are used with push pull drivers, rather like with audio amps.

David (RW's) warning is very valid there is now a huge amount of crap out there on various social media sites

Ed
Ed_Dinning is offline  
Old 21st Mar 2023, 12:36 am   #14
DrStrangelove
Banned
 
Join Date: Jan 2023
Location: Neath, Port Talbot, Wales, UK.
Posts: 286
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

I'd forgotten about the lamp mantle so beloved of the Late Nuclear Boyscout: I have a fairly old camping gaz lamp with a mantle, that makes the geiger click too.

As I understand it the thorium has been removed from more modern examples.

I cobbled together an inverter for the GM4 tube using a large prewound pot core with some added thick primary winding.

Worked a treat driven by a big fat MosPower pulsed at 1kHz or so though I doubt if it would last long before the insulation on the secondary failed.
DrStrangelove is offline  
Old 22nd Mar 2023, 11:46 pm   #15
Cruisin Marine
Heptode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

I am researching this still and getting further and further.... but, one aspect I don't know the answer to is - can the Geiger Muller tube be used in a screened aluminium box? Or should it be plastic?
A dumb question maybe, but one that I have to ask.
I don't intend to have a remote sensor, all built in one box.
Thanks.
__________________
"Behind every crowd, there's a silver Moonshine"
Cruisin Marine is offline  
Old 23rd Mar 2023, 12:18 am   #16
Hengist
Triode
 
Join Date: Feb 2014
Location: London, UK.
Posts: 20
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Most Geiger-Muller tubes will detect beta and gamma radiation. Some, such as the Mullard MX168, will detect alpha radiation as well. An aluminium sheet will certainly stop alpha radiation but beta radiation can penetrate thin aluminium. Gamma radiation will penetrate aluminium sheet.
__________________
Regards,
Tim
Hengist is offline  
Old 23rd Mar 2023, 7:39 pm   #17
DrStrangelove
Banned
 
Join Date: Jan 2023
Location: Neath, Port Talbot, Wales, UK.
Posts: 286
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Goodness me, beta particles can penetrate 3cm of aluminium.

I didn't know that.

As against 1mm of lead.
DrStrangelove is offline  
Old 23rd Mar 2023, 11:44 pm   #18
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Quote:
Originally Posted by broadgage View Post
A useful test source is an old stock pressure lamp mantle. Newer production might be non radioactive but older ones contain radioactive thorium.

"Uranium glass" has come to mean a style of glassware that may not contain any actual uranium. Genuine antique uranium glass can be a useful test source, but modern production may not be.
You can get thoriated tungsten electrodes (coded with a dip in red paint at one end) from welding equipment suppliers who sell them for TIG welding. There are also Ceriated and Lanthanated types which aren't radioactive. Alternatively, if you know a welder, he might give you a few stubs left over when too short for the torch to grip. These are typically 2% Thoriated.

Some WWII photoreconnaissance lenses used lenses doped for anomalous refractive index and the dopant was a radioactive salt For added fun the 'hot' element was often the front one and the glass was slightly water-soluble! Do not clean by licking! This stuff after the war turned up in some specialist telephoto lenses as well... until it was thought better to leave this technology behind.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 24th Mar 2023, 2:32 am   #19
Chris55000
Nonode
 
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

One of these any good?

https://www.ebay.co.uk/itm/115274062...mis&media=COPY

. . .They appear to give about the right sort of h.t. voltage for a G.M. tube off a 3–5V supply, and you can always add a 78L33 or 78L05, or an LM317 circuit with a 240 Ω & a 1k preset, between your battery supply and this module to give your desired output!

Chris Williams
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!
Chris55000 is offline  
Old 24th Mar 2023, 10:44 am   #20
DrStrangelove
Banned
 
Join Date: Jan 2023
Location: Neath, Port Talbot, Wales, UK.
Posts: 286
Default Re: Step up transformer from 9 to 575 volts for a Geiger tube.

Just dug out a Griffin & George geiger counter with a Mullard GM tube.

The background count is low, a count every 5 seconds or so.

The uranium glass doubles or trebles the count.

The mantle in the camping gaz lamp is hot compared with the uranium glass.

The mantle in the Lidl gas lamp is as inert as expected.
DrStrangelove is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 6:19 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.