Back in the early 80s I set up something kind of similar but it used an electric eye to stop my "homemade" tricklers....The first tricker was a modified Redding that used a gearmotor for fast charging...The second modified trickler used a second gearmotor only slower to trickle in after the first motor was shut down by a preliminary "electric eye" which was activated by beam position....the second and slower trickler trickled in the last part of the charge until a second "eye" shut it down at zero.....It was slow and only was accurate to a tenth of a grain because of powder clumping in the Redding trickler....If I only knew the "straw" trick back then....I made a second automatic powder scale a few years later with a stepper motor and digital circuitry this one was faster and only used one "trickler" but again the accuracy was only a tenth of a grain....I trickle in to a "kernal" or so when doing it by hand...But thats just me...

The unit was very bulky and was dismantled twice for moves a couple of houses and relationships ago....Parts were lost and it was never put together after that.....Then they came out with the "Charge masters"......But I never bought one I only load 1 or 2 thousand rounds a year now for my rifles and weigh every charge by hand on an old Bonanza model "C"...

The authors idea is good..because the beam scale when cared for and maintained properly should never read a grossly erroneous charge...Most electronic scales have the possibility to error that the user may be unaware of. The mechanics of a beam scale will reduce the likelyhood of major error....Within reasonable affordability a good beam scale (without magnetic dampening) will often weigh more accurate than an affordable electronic scale.....

Just my .02,
Randy