The frequency that it seems to manifest itself at is also interesting. 120MHz or so… Hmmm, I wonder if it changes frequency if the length of the coax is different. If you have a much longer piece of coax with a BNC termination on it I'd try that and see if the frequency is lower
Maybe some broadcast signal resonates somewhere there; In any case this is a good prove of Murphy and this should be the first lesson in any engineering,
I've just imagined Dave running around a building with a scope, jumping up off a chair in random rooms and then gushing with Davecitement about the effect 😀 Awesome!
I see many of us jumping on our seats, and after all the problem is simple, you must have a ghost on your lab. Search under the table, if you can not find it call a priest and buy some candles.
If its caused by static isn't it EMI it's picking up? like if someone starts a lawnmower up the street you can sometimes hear it through speakers or in my case guitar amp?
Very good. I could not reproduce it myself but the principal is correct with inductance, as anyone would know if they have a strong background in Electronics. You have a very basic high impedance tank circuit thats picking up a HV static charge. Creating the static depends on Material, Temp, Humidity and several other things. I never thought of this anomaly before, but it is interesting. Cheers!
It's not the chair suspension, I can get the same effect by wiping my jumper across the chair. It is simple static generation, nothing more. I just found the chair more repeatable and higher amplitude. The fascinating thing is how this manifests itself into the sin x/x like waveform.
Hello Mr ESD generator ! Hehehe
What is a 'crow-probe'?
Same thing happens with my Rigol.
the probe coax cable is loose on the BNC connector, no f*** magic, no ghost, just a bad contact initiated by the jumping guy…
Could it be that it is the springiness of your chair which causes this glitch somehow?
shielding in coax seems piss poor
The frequency that it seems to manifest itself at is also interesting. 120MHz or so… Hmmm, I wonder if it changes frequency if the length of the coax is different. If you have a much longer piece of coax with a BNC termination on it I'd try that and see if the frequency is lower
Maybe some broadcast signal resonates somewhere there; In any case this is a good prove of Murphy and this should be the first lesson in any engineering,
I've just imagined Dave running around a building with a scope, jumping up off a chair in random rooms and then gushing with Davecitement about the effect 😀
Awesome!
try it again without a probe attached
I see many of us jumping on our seats, and after all the problem is simple, you must have a ghost on your lab.
Search under the table, if you can not find it call a priest and buy some candles.
that's an Australian phenomenon. in the northern hemisphere, you have to sit down on the chair to generate it.
"i can get it… uhhh… many many places" – I was expecting "matter of fact, i've got it now" to follow that, heh.
Or something that causes a spark. Maybe try making a spark and see if it picks up something similar?
If its caused by static isn't it EMI it's picking up? like if someone starts a lawnmower up the street you can sometimes hear it through speakers or in my case guitar amp?
Very good. I could not reproduce it myself but the principal is correct with inductance, as anyone would know if they have a strong background in Electronics. You have a very basic high impedance tank circuit thats picking up a HV static charge. Creating the static depends on Material, Temp, Humidity and several other things. I never thought of this anomaly before, but it is interesting. Cheers!
It's not the chair suspension, I can get the same effect by wiping my jumper across the chair. It is simple static generation, nothing more. I just found the chair more repeatable and higher amplitude. The fascinating thing is how this manifests itself into the sin x/x like waveform.