Aha! Was not aware of that, but will try it if we get our hands one some.[/COLOR]The neon lamps "regulate" around 70 V each, so connect them in series, and use instead of the Zener, or in parallel to it. You can also use a biased LM317T voltage regulator. I saw Motorola HV integrated regulators , MC1466L, for up to 500 V DC.
Well, when you mention it, it is the 100Hz which is the main problem in our circuit, any ideas why? We though maybe the 100Hz derived from the 50Hz in some way.Have you verified that the interfering signal is 50Hz and not 100Hz? And why the orientation of the -200V supply? Hard to be sure if it's at the root of your problem, but I suggest you ground the +ve output of the rectifier and move R1 to the negative side. That will at least eliminate that as a possible reason.
As jiripolivka pointed out, it's possible that the AC supply is carrying some RF interference. I suggest paralleling D1-D4 with capacitors of around 0.01uF of suitable voltage ratings.
But then no radon gas will enter the detector chamber, but maybe we can try covering the box containing the detector with alu. foil.As you write that your diode is covered by cloth, please try to cover it with an aluminum foil, so no light can reach it. At the diode your low-level signal starts, so be sure you amplify only what you want to amplify.
Yes, it's derived from the 50Hz mains frequency. But the fact that it's 100Hz implies that the source of the interfering signal is the rectified power supply ripple rather than direct mains. That narrows down the possibilities.Well, when you mention it, it is the 100Hz which is the main problem in our circuit, any ideas why? We though maybe the 100Hz derived from the 50Hz in some way.
I understood that. I was not suggesting that you use a positive supply. You can get a negative supply with this arrangement:About the negative bias: The detector needs a negative bias to not break down the diode. Since the alpha-particles are positive we need negative 200V.
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