1 to 10 Gohm resistors are quite normal in condenser microphones, but does 1 Tohm or 1 Pohm still have an audio application?
Elvee, it is impressive that you roll your own test and measurement equipment. Props to you. If you look at a datasheet for a commercial tera ohm meter, you will see that the uncertainty a percentage instead of ppm uncertainty. As you go higher in resistance, you no longer can trade problems to optimize what you want to be least uncertain about. You wind up with more and more uncertainty as resistance gets higher.
In my experience, a 1T resistor must be at least shielded and possibly also guarded in order to measure it accurately. Pico amps in audio are not relevant in the sense that you want to observe pA current by itself. Instruments that can measure pA accurately are expensive.
Direct application, no: I don't see a DIYer picking a 820G resistor from a drawer, and measuring it to make sure it is still OK.
However, people meddling with ESLs or plasma speakers could find high-resistance measurements useful.
Even in less specialized fields, the ability to measure high resistances or tiny leakage currents can have a relevance for audio: a connector that has been used in harsh field conditions can be soiled or accumulate some dirt.
This contamination may cause a leakage <1nA, but it will be almost pure noise and random DC level fluctuations, and could corrupt a low level signal from a microphone or similar.
There are other ways of pinpointing such an issue, but if you have a teraohmmeter handy, it is an easy option.
As I mentioned, I am going to build an ionization chamber, and very high value resistors are required
It is just a hobby since I am now retired. I have already built a GM counter: https://www.diyaudio.com/community/threads/a-psu-controller-on-a-shoestring.330601/post-5627299
An ionization chamber has different properties, and I would like to match the sensitivity of the GM with it
An ionization chamber has different properties, and I would like to match the sensitivity of the GM with it
Interesting indeed. I have an acquaintance who is trying to create a fusion reactor on the ground floor of his rural 2-story home. I never hang around very long.
A short update: the instrument has been finalized and calibrated a little more than one month ago, and I have checked the stability of the calibration.
As expected, the 1G and 10G have remained rock-solid, and the 100G has somewhat drifted, but surprisingly not in the expected direction: the 100pA measurement current has increased to 102pA, which means that the circuit has improved.
With the nominal values, the current was only 95pA, because 5pA were lost somewhere. I compensated this loss, but now it has been reduced to 3pA.
I will continue to monitor the evolution from time to time.
The instrument stays in my lab, where the temperature and humidity are practically constant, and the enclosure is almost airtight, meaning external influences are minimal
As expected, the 1G and 10G have remained rock-solid, and the 100G has somewhat drifted, but surprisingly not in the expected direction: the 100pA measurement current has increased to 102pA, which means that the circuit has improved.
With the nominal values, the current was only 95pA, because 5pA were lost somewhere. I compensated this loss, but now it has been reduced to 3pA.
I will continue to monitor the evolution from time to time.
The instrument stays in my lab, where the temperature and humidity are practically constant, and the enclosure is almost airtight, meaning external influences are minimal
Hi Elvee,
sorry for the O.T. I was just looking for you. If you can take a look to "tubes & valves" to the Salas line preamp thread.
I posted here, since I got a problem with your SSR (regulator) a sort of oscillation that send a continuous hiss at the preamp output. Thanks, Indaco
sorry for the O.T. I was just looking for you. If you can take a look to "tubes & valves" to the Salas line preamp thread.
I posted here, since I got a problem with your SSR (regulator) a sort of oscillation that send a continuous hiss at the preamp output. Thanks, Indaco