Charles, After modifying the CDV-715 Ion Chamber and scratch building the rest of the circuit from your Web Site I have some questions a possible improvement...
I would bet that the majority of pulses are from alpha particles coming off of exposed metal in the can, even the center wire and especially any solder joints....
Charles wrote: ... My large cookie tin chamber typically shows a hump with a 24 hour period, which is what would be expected from cosmic rays, but I don't ...
I not even willing to assume it's cosmic rays. It's more likely something in the local environment, although I haven't figured out what. I'm pretty sure it...
... It almost would seem to be a problem of detecting everything. 8-) The range of sources and energy levels which can cause a detectable 'event' is all over...
Just remember that if there is any suspicion that the source of the bump is caused by something in deep space, and that there is some directionality in play,...
I've seen plots of the rate of coincidence detection as a function of the distance between detectors. It's a good test of cosmic ray detection because you can...
I really believe it's local stuff, probably radon. You can see that it's drawing the same bump today. So closely, in fact, that I'm going to hold the uranium...
I will assume the GC has a single pulse output you can use. For the simplest solution, I would increment a single chip, multi-stage binary counter (4040 looks...
... Charles, I would like to add a event counter to your modified CVD-715 circuit I'm try to get a idea of the number of ping (hits) on the meter for one...
How about monitoring the voltage across the meter? Measure both meter terminals relative the the battery negative terminal with little deflection and with...
I think I would make some significant changes to the chamber. For one, I would fill it entirely with CO2 and seal it, making sure to get all the water vapor...
It looks like one side of the meter goes to "ground" or the negative side of the battery, so measure the voltage from there to the other side of the meter when...
Is the only battery voltage 3 volts? What sort of alarm do you want? Is there room for another battery? How are you going to turn off the alarm? Oh, look at...
I think the hysteresis I described has an "issue" or two, but one step at a time. The problem is that I said to use a "high value" pot but if it's too high,...
Yes, that's very close to what I was suggesting. Instead of hysteresis, they have a latching circuit. I was going to suggest the PNP to drive the alarm. If...
Not really, just electronics suppliers. I suspect latex paint remains conductive, compared to a good insulator. But it will out-gas water vapor for a while. In...
I need the answers to the questions, first: what kind of beeper, what kind of level setting control, behavior of the alarm, available voltage from the battery...
paint with metal fillers can be tried. Copper paint in spray cans worth a try.Stay away from aluminum paint, since Al forms an insulating oxide. Another idea...
Whatever happened to green Gliptal (or Gliptol)? That was a slightly conductive paint for spreading charge evenly. Oh, yeah, how about powdered zinc primer...
It's not regular insulating Glyptol. Here it is: http://www.glyptal.com/9921Tech.pdf It is with an "a." I'm liking the zinc primer. That's everywhere....
You will need a circuit to generate the sound if you use a simple piezo or dynamic speaker. Piezo buzzers have the electronics to produce the tone built in. I...
I have a first cut under Files/Images/geigeralarm.jpg. I used an LM393 dual comparator and a current booster transistor. The first comparator on the left will...
