Author Topic: CRO "floating" inputs?, fail?  (Read 13204 times)

0 Members and 1 Guest are viewing this topic.

Online Simon

  • Global Moderator
  • *****
  • Posts: 17728
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: CRO "floating" inputs?, fail?
« Reply #25 on: February 20, 2011, 03:23:14 pm »
Yea i realize people tent to think user with higher post counts may have more knowledge. Big mistake (one I made often on another certain forum where mods often came out with outlandish claims to look clever but were actually providing fatally inacurate information like a heated discussion over RCD's and what the correct values for safety were. Due to the mods attitude I left as it was plain accuracy of knowledge was not a priority there only ego). Firstly some of us hang out here more, secondly someone who just joins may be very knowleageble but just be new. By 3 posts making one an expert i was refering to the use of this forum and knowlege of it's members not electronics in itself.

No offence intended of course, I'm happily corrected. One should never take any information for 100% accurate particularly where life is endangered and usually letting the discussion run for a bit allows for things to be thrashed out properly and a sane conclusion reached
 

Online mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 13695
  • Country: gb
    • Mike's Electric Stuff
Re: CRO "floating" inputs?, fail?
« Reply #26 on: February 20, 2011, 03:26:58 pm »
If only someone could figure out an algorithm to calculate posters' signal-to-noise ratio instead of post count...
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Online Simon

  • Global Moderator
  • *****
  • Posts: 17728
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: CRO "floating" inputs?, fail?
« Reply #27 on: February 20, 2011, 03:54:47 pm »
yes quite, unfortunately we live in the real world
 

Offline saturation

  • Super Contributor
  • ***
  • Posts: 4787
  • Country: us
  • Doveryai, no proveryai
    • NIST
Re: CRO "floating" inputs?, fail?
« Reply #28 on: February 20, 2011, 09:28:12 pm »
In some boards, you can rate posts for their quality, but few forums use it consistently, you'd have to encourage it.  It doesn't speak for accuracy of the content, but that folks found a post helpful.  If peers read the post and gave it a bad mark, then the good and bad will balance each other.  If the writer later deletes the post, votes disappear too, so percentage of votes can be used as an index of the poster, than raw thumbs up or down numbers.

If a member has only 3 posts, but all rated well, he'd have a 100% rating, but if another poster simply posted 'wow', 'nice', 'awesome' type posts and are not rated, even if has 1000 posts, he'd have no rating or even negative ratings.

Its not perfect, but its better than simple raw total posts.
 

If only someone could figure out an algorithm to calculate posters' signal-to-noise ratio instead of post count...
« Last Edit: February 20, 2011, 09:30:15 pm by saturation »
Best Wishes,

 Saturation
 

Offline EliminateurTopic starter

  • Regular Contributor
  • *
  • Posts: 179
  • Country: ar
  • Electronic's Technician
Re: CRO "floating" inputs?, fail?
« Reply #29 on: February 20, 2011, 09:41:44 pm »
intrigued, i put the DMM in continuity test and to my horror i find that the input "outer rim" of the BNC connector is part of the chassis which is GROUNDED to mains ground!, WHAAAA, FAIL! which essentially grounded the neg output of the bridge rectifier(-150Vdc~) when i touched it, aren't CRO inputs supposed to be fully floating?.

Congratulations, you learned that scopes are grounded in the true traditional time honored method! *pins badge of honor to your chest*

Dave.
tehehe i'm gonna wear my badge of fail proudly, best way to learn stuff if by blowing it up :D
 

Online Simon

  • Global Moderator
  • *****
  • Posts: 17728
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: CRO "floating" inputs?, fail?
« Reply #30 on: February 20, 2011, 09:43:53 pm »
hm providing you use RCD's and any other precautions
 

Offline ziq8tsi

  • Regular Contributor
  • *
  • Posts: 80
Re: CRO "floating" inputs?, fail?
« Reply #31 on: February 20, 2011, 11:12:43 pm »
If only someone could figure out an algorithm to calculate posters' signal-to-noise ratio instead of post count...

I am a huge critic of the whole concept of Artificial Intelligence.  But the problem you define actually is one that is more or less solved, albeit by harnessing human opinions.

I would propose a system similar to that used to rank reviews on Amazon.  Forum members would have an optional binary vote on each post they read.  It could be "helpful"/"not helpful", or "interesting"/"not interesting", depending on what the goals of signal-to-noise consideration would be.  Call it "good"/"bad".

Forum members could then be ranked by total goodness, instead of total posts.  Or more extremely they could be ranked by absolute goodness, which is total goodness minus total badness.

I believe that this would work and would be relatively easy to implement (compared to AI).

However, I think that DLJ's EEVblog time is better spent researching and filming blog entries rather than hacking forum software or screening real life people to do so.  Therefore we should expect members to make their own decisions about the credibility of individual posters, based on standards similar to those that have been used on Usenet for decades.

After several weeks' reading the forums, or less if delving back into historical posts, any sensible user should get an impression about each of the regular posters, and will then know if a poster is reliable, or is frequently corrected, or simply has to respond to every message, whether s/he can add anything useful or not.
 

Offline Chasm

  • Regular Contributor
  • *
  • Posts: 211
Re: CRO "floating" inputs?, fail?
« Reply #32 on: February 20, 2011, 11:22:28 pm »
User rating systems are often the a major source for problems and flamewars between users.

I'm not convinced that they are worth the hassle on this or any other board.


In some boards, you can rate posts for their quality, but few forums use it consistently, you'd have to encourage it.  
[....]
 

Offline grenert

  • Frequent Contributor
  • **
  • Posts: 448
Re: CRO "floating" inputs?, fail?
« Reply #33 on: February 21, 2011, 05:21:56 am »
 

Offline saturation

  • Super Contributor
  • ***
  • Posts: 4787
  • Country: us
  • Doveryai, no proveryai
    • NIST
Re: CRO "floating" inputs?, fail?
« Reply #34 on: February 21, 2011, 05:37:32 pm »
I'm not a sysop, so I don't know how well it works.  But in other technical boards, I'm been paid for my posts based on ratings, and its not much, but its a free 100+ US$ a year, its like getting free test gear every year.  Some top posters 10,000+ a year based on the quality of their posts. 


User rating systems are often the a major source for problems and flamewars between users.

I'm not convinced that they are worth the hassle on this or any other board.


In some boards, you can rate posts for their quality, but few forums use it consistently, you'd have to encourage it.   
[....]
Best Wishes,

 Saturation
 

Online Simon

  • Global Moderator
  • *****
  • Posts: 17728
  • Country: gb
  • Did that just blow up? No? might work after all !!
    • Simon's Electronics
Re: CRO "floating" inputs?, fail?
« Reply #35 on: February 21, 2011, 05:43:12 pm »
it is a tricky thing to get right as it is all based around peoples opinions and perceptions. Personally unless someone is offering a clear cut commercial deal I'd distrust any board that pays members although I admit I'm not falmiliar with how it works
 

Offline Bored@Work

  • Super Contributor
  • ***
  • Posts: 3932
  • Country: 00
Re: CRO "floating" inputs?, fail?
« Reply #36 on: February 21, 2011, 06:50:47 pm »
In some boards, you can rate posts for their quality, but few forums use it consistently, you'd have to encourage it.  It doesn't speak for accuracy of the content, but that folks found a post helpful.

It is a rather stupid mechanism. The result is that postings that make readers feel cozy and good and support their prejudice get voted up, not the ones that are correct.
I delete PMs unread. If you have something to say, say it in public.
For all else: Profile->[Modify Profile]Buddies/Ignore List->Edit Ignore List
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf