Thank you Chuck, I think you have something there, that is probably driving the choppers. The meter had a little more jitter than before after the mod, that is why I modified the integration filter caps. I like the slower response anyway. When I have time I'll share my mods for the Fluke 540b, Much better than before, can transfer at lightning speed. The suggestion of using a voltage regulator (LM1117) for the 1.35v mercury battery from the EEV Blogs Didn’t pan out. Its not a reference, it’s a voltage regulator. You don't need accuracy but stability.
Dallas > Date: Tue, 9 Sep 2014 20:30:30 -0400 > From: [email protected] > To: [email protected] > Subject: Re: [volt-nuts] Finally got around to modifying my Fluke 845ab with > LED's > > Hi Mark, > > I have an itty bitty white led, probably called a T-1 size, and it > glows dimly for a long time after you shut it down. They all pretty > well have to. > > I think what you are seeing with your analyzer is the blue/UV component > that drives the phosphor element. It will run just as fast as any old > style LED. > > I also think that the blue/UV component, which is very bright, is what > is driving Dallas's chopper. > > But enough on that. I wasn't trying to criticize, just make mention of > something I noticed in my own work. > Where I got to thinking of this is when I burned out the strobe tube > in my G-R strobotach. Replacement tubes were in the $300 range, so I > knew that would never happen, so I was thinking of making a solid state > replacement using a handful of those wonderful little white LED's. > They would certainly be bright enough, but I'm pretty sure the phosphor > hang would make them unsuitable for stopping motion... your eye would > see a blur instead of the razor sharp image you get with the strobe tube. > > -Chuck Harris > > > > Mark Sims wrote: > > I would probably use green or yellow LEDs, but the white ones should not > > be a > > problem. I built an LED analyzer/integrating sphere and one of the features > > is a > > circuit that optically measures the LED driver PWM frequency. It can also > > detect > > the minute variance in LED intensity from an LED driven by a 950 kHz boost > > converter. It also had no problems with a white LED driven at 4 MHz from a > > signal > > generator. You see the long persistence phosphors mainly in large lighting > > LEDs > > and not in small indicator LEDs. > > _______________________________________________ > > volt-nuts mailing list -- [email protected] To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the > > instructions there. > > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
