[volt-nuts] Finally got around to modifying my Fluke 845ab with LED's

[Dallas Smith]

My scope shows that the copper is working ok. May try amber or yellow to see if the performance is better.
See page 13: http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/HB/Data%20Sheets/C513A%20WSN%20WSS%20MSN%20MSS%201042.pdf

 
> Date: Tue, 9 Sep 2014 16:42:30 -0400
> From: cfharris at erols.com
> To: volt-nuts at febo.com
> Subject: Re: [volt-nuts] Finally got around to modifying my Fluke 845ab with LED's
> 
> Hi Dallas,
> 
> The thing is, CdS cells peak sharply at about 560nm, which is green/yellow.
> They are blind to most of white light... especially to the blues which are
> prominent in white LED's.
> 
> White LED's are designed purely for bulk illumination.  They have a very
> slow response so that they won't flicker when used for domestic lighting
> off of a 50/60Hz power source.
> 
> There are also green yellow and red LED's that are designed the same way,
> but there are many that switch quickly too.
> 
> -Chuck Harris
> 
> Dallas Smith wrote:
> >
> >
> >
> > Hi Chuck,
> >
> >
> > Its only 84Hz, It had the offset
> > problem long before I made this mod. The new meter at work many decades ago
> > also had this problem.
> >
> >
> > I pick white so the full spectrum would
> > be covered by the Csd's. Checked waveforms with scope, has sharp rising and
> > falling edges. This mod may not be as elegant as a Linear Devices copper mod,
> > but at lest I will not have to mess with the shielded front end.
> >
> >
> > The
> > offset may be due to the bias current in the front end reacting with the different
> > polarities.
> >
> >
> > Dallas
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