Simple geiger counter power supply design - Page 1
Forum section: electronics / projects

author: Snake____1
author_rank: Contributor
timestamp: July 16, 2019, 08:58:58 am
content: Hello, I am in the process of building a simple handheld geiger counter. As known by many the old sensor tubes need a voltage of around 400v DC, therein lies my question.How can I make a simple power supply for this? Preferably something I can run from a single 18650 cell.Attached is a simple supply I bought that I thought I could reverse engineer. But as you can see the sot23-5 and to-252 are sanded down...Any bright ideas?

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 16, 2019, 09:11:46 am
content: Search for Nixie power supplies.With a voltage tripler on its output, I used one for a Dekatron project, which requires 510 volts.Edit, from the photo, it appears that the tripler is already built in

author: jaromir
author_rank: Unknown
timestamp: July 16, 2019, 06:22:24 pm
content: Nixie power supplies are designed for typical nixie load, that is a few mA to few tens mA, depending on how much nixies you have. Geiger detectors, on the other hand, do require much less current, say two or three orders of magnitude less.Quiescent current of simple nixie supplies isn't stellar, but there are circuits better suited for Geiger detectors, like the one from linkhttps://mightyohm.com/blog/products/geiger-counter/it has quite low quiescent current and supply range suitable for single Li-Ion.

author: Marco
author_rank: Super Contributor
timestamp: July 16, 2019, 06:29:19 pm
content: Lots of threads about this lately. As I said in the other thread,the Thereminodesign seems hard to beat for it's simplicity.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 16, 2019, 06:35:36 pm
content: Quote from: Marco on July 16, 2019, 06:29:19 pmNoticed that as well.Are people starting to fear a nuclear war or something?

author: iMo
author_rank: Super Contributor
timestamp: July 16, 2019, 06:35:50 pm
content: The GM tube draws nothing, unless an event happens. The current peak (maybe 100us long) is usually limited with a resistor like 5-10Meg.Normally you get a ~dozen ticks per minute, unless you mess with some active material.. (PS: don't do it at home(!!), but an old WWII meter's dial from a Junkers plane makes 4000 ticks per minute even today). Mind the GM tubes have a limited life, based on number of events.The power supply I built in past consisted of 3 transistors, a choke, 3 fast diodes with 3 10n/600V caps and 3 150V zeners as the feedback to get something stable like 450V. I will search for the schematics, the GM stuff worked several months off a 9V battery..PS: MPSA42 was the driver afaik..Ok, here - the second schematics from top was the one, we built several and it worked fine:http://www.techlib.com/science/geiger.htmlThe HV diodes were some "fast" 1000V diodes as I can remember, not sure the 1n4007 is the best choice there..

author: JimRemington
author_rank: Regular Contributor
timestamp: July 17, 2019, 02:59:17 am
content: I was recently inspired by a design from an article in a publication titled Aerovox (below) and modernized it by replacing the spark gap with 3 200 V Zeners, which rectify in the forward direction and limit the voltage in reverse.In the pic below, the cap is 82 nF, 600V. I used a speaker output transformer from a tube radio. Four brief pushes of the "pushbutton" (blue ellipse) result in ~600V across the cap, which had an unloaded decay time in excess of 20 minutes! Works great with the Geiger tube shown in the photo, of unknown manufacture (450V threshold voltage), so just need to add the click amplifier, and I'm ready for the forthcoming nukes.Doesn't get any simpler than that.For quantitative work, the guy runninghttps://rhelectronics.net/store/diy-geiger-counter-kit.htmlhas some really nice, low power HV power supply modules for PM and Geiger tubes. I've bought a couple from him and they are well designed, as well as extremely efficient.