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"I respectfully disagree.......My modeling perspective is to "stand on the detector's input node and look back towards the coupling capacitor" and what do you see?"I'm not talking about the GM tube

I respectfully disagree.......My modeling perspective is to "stand on the detector's input node and look back towards the coupling capacitor" and what do you see? You see a randomly occurring -(2+)V

Roger said: " Peter, Since the 900+V bias is blocked by the coupling capacitor to the detector circuit, you don't have to worry about that."Actually, you do have to worry about that, in my opinion.

READERS don't try this circuit at home either!It is showing negative HV feed, which puts the magnetic shield wrap at HV to ground- a big nono (deathtrap).Geo

Peter, Since the 900+V bias is blocked by the coupling capacitor to the detector circuit, you don't have to worry about that. The simple notion of a GM I modeled over 2 yrs ago was a 2.6V (the minimum

Speaking of fun I found this at Wikipedia and It got me thinking..... So, with all those pins coming out and making a resistor divider from RegHV to ground, it would not be hard to incorporate this

Roger: The series regulator flavor sounds interesting too! I don't have any idea as to what a spice model of PMT or a gm tube would be. I wonder if there are spice models for gas discharge tubes ? ESD

Right, while no9t harmless, a CDV-700 with it's high resistance secondary winding ( I need to measure that value today) and nominal 5 Million Ohms between the high resistance rectifier and the probe

1) yes, that is exactly what happens. 2) yes, you don't need too many uA's to get to mA's in capacitive discharge and hurt yourself at 900+V, or more. A HV bypass capacitor of larger capacitance could

Infinite Impedance Scope Probe schematic: if need be, the LT Spice file will suffice., Geo To: "CDV700CLUB" <[email protected]> Sent: Sunday, April 3, 2022 10:05:03 AM Subject: Re: [CDV700CLUB]

Please post that schematic. I want one!! Geo To: "CDV700CLUB" <[email protected]> Sent: Sunday, April 3, 2022 10:05:03 AM Subject: Re: [CDV700CLUB] Question and an interesting site for those that

I have that Spice, and another one too, but am not adept with them. They do draw a mean schematic tho. Geo To: "CDV700CLUB" <[email protected]> Sent: Sunday, April 3, 2022 10:05:03 AM Subject: Re:

" My point was that the negative spike from a properly biased GM tube is low enough impedance source excitation to drive a ~9K input impedance one-shot in a Lionel. So, if the impedance looking back

I have one in my LTSpice simulation program... :-) LTSpice is free from Linear Technology. rogerw

Roger said: " That spike is what I was referring to as a "pulse." perhaps bad terminology" That is indeed the pulse. Where do I get an infinite impedance scope probe? Isn't the scope itself 1M Ohm

" Geo, I want to return to your question one more time and ask about your predicate....... Does the GM tube really go to ground? I agree that the transient current does go to ground, but when I was

Geo, If I were to put an infinite input impedance scope probe on the anode of the GM tube in, say, a Lionel, I am assuming I would see then a momentary -5V (or thereabouts, as low as -2V I think is

GM tubes don't "put out a pulse". They short to ground like any other neon tube, but recover quickly when the bias voltage drops down to the tubes conducting value (that's the Quench gas at work).

On the modeling question, probably yes, but I would need to understand more. Need to see a schematic and understand the PM tube discharge and see where the output is taken..... somewhere in the

Geo, I want to return to your question one more time and ask about your predicate....... Does the GM tube really go to ground? I agree that the transient current does go to ground, but when I was