User talk:Rwl10267

Please do not add inappropriate external links to Wikipedia. Wikipedia is not a mere directory of links, nor should it be used for advertising or promotion. Inappropriate links include (but are not limited to) links to personal web sites, links to web sites with which you are affiliated, and links that attract visitors to a web site or promote a product. See the external links guideline and spam policy for further explanations. Since Wikipedia uses nofollow tags, external links do not alter search engine rankings. If you feel the link should be added to the article, then please discuss it on the article's talk page before reinserting it. Thank you. [1] (Requestion 21:18, 25 April 2007 (UTC))[reply]

I left the above courtesy message so that you can read it and the Wikipedia policies that the links point to. They are very informative. (Requestion 21:18, 25 April 2007 (UTC))[reply]

Shunt (electrical)[edit]

In my day, we used moving coil meters which typically have a full scale deflection measured in mV and/or μA. Whether the meter was a voltmeter or an ammeter was defined by whether it had shunts or multipliers connected, rather than by the nature of the meter itself. But I guess nowadays everyone is using digital voltmeters. SpinningSpark 17:44, 29 May 2008 (UTC)[reply]

Thanks for your comment. I agree. I'm not completely up to speed on the old D'Arsonval movements, but I do not believe that they ever measured current directly. Any meter with implied current measurement was in fact a volt (or millivolt) meter that measured the voltage developed across a built-in shunt. Such is the case today when attempting to measure current using a shunt -- you always do it indirectly by measuring the shunt voltage. That's why I changed your edit. I thought it was more accurate to state that a millivolt meter is used to measure the shunt voltage as opposed to an ammeter. The latter approach would in reality measure the voltage across a shunt, across a shunt. For further info see this broad selection of current shunts.Rwl10267 (talk) 18:16, 29 May 2008 (UTC)[reply]

Well, I could equally argue that a voltmeter was really an ammeter with multiplier resistors in series. Both moving coil and moving iron type movements rely on magnetic fields which are more directly related to current through the coil than voltage across it. So it is more accurate to call them ammeters, but you can always consider the meter to be a millivoltmeter if convenient to the application because for a specific meter there will be a specific voltage corresponding to fsd. Anyway, lets leave it at that - I'm happy for the article to stay as it is. I expect that no-one is much interested in mechanical movements anymore.

Oh, just one last by-the-way. It is not correct that you ALWAYS measure current indirectly. I have often been interested in very small currents and used the ammeter "neat" without any shunt. SpinningSpark 21:13, 29 May 2008 (UTC)[reply]

Exceptions to every rule, I guess. I suppose you could do that by measuring coil resistance first and using that value to calibrate readings? I'm afraid that we are both exposing our substantial age with this discussion. --Rwl10267 (talk) 16:02, 30 May 2008 (UTC)[reply]

Image tagging for File:Malcolm McNab DSC0167-1-.jpg[edit]

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Correction of a signal source image[edit]

The middle of [image] has - Vcm, shouldn't it be +Vcm ?--Diraniyoussef (talk) 07:17, 20 January 2021 (UTC)[reply]