Possible replacement for my now partly failed ST-360 Counter

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Richard Hull
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Re: Possible replacement for my now partly failed ST-360 Cou

Post by Richard Hull » Fri Mar 03, 2017 3:52 pm

GM tubes, typically, need no amplification whatsoever in an electronic GM counter. Some counters do pulse shaping/forming or invert the pulse, but the signal directly from a GM tube is measured in volts or tens of volts!

Circuit digrams are best posted in the radiation forum for radiation instruments.

Richard Hull
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Dennis P Brown
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Re: Possible replacement for my now partly failed ST-360 Cou

Post by Dennis P Brown » Sat Mar 04, 2017 5:44 pm

Thank you Richard.

Did not know about GM tube signals (nice to know that); makes sense how the ST-360 handles that signal. Petty much confirms were my problem is; the U15 chip is easy to obtain. I will add that their sub-circuit for detecting a GM or scintillation signal is an ideal pre-amp/amp and voltage comparator system. Since I am ordering the Op-amp chip (with spares), I guess I will order all the components (other chip, resisters and caps) and copy that nice system for future projects. Saves me a great deal of time and trouble trying to balance a chip/feed-back circuit system for where a BF3, GM, and scintillation tube all like to operate! Would be easy to add a counter to that final chain. Might consider building a neutron/scintillation detector system for fun, electronic training/practice and of course, use with the fusor. But first, get he ST-360 fully working again.

Having the schematic was handy for not just understanding that sub-circuit but following it through its entire path until data display - the main special monster chip plays only a minor role (and is of no importance for the detection and counter display.) Again, good to know.

I will post the circuit later this week.

Aside: my DP pump has a heater problem; this forced me to break my system down so I can get at the heater section. Does give me an opportunity to add water cooling to the main chamber, and do a few changes/mods to make it a bit better. I am running into a host of issues since my neutron success - worst, they were all caused by me pushing my system too hard ... .

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