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Rifles, Reloading, Optics, Equipment
Reloading
Electronic vs Balance Beam scales
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<blockquote data-quote="boomtube" data-source="post: 274791" data-attributes="member: 9215"><p>"I have heard that florescent lights, dimmer switches, mobile phones, RFI and even static electricity from the neighbors cat (another post, another website, no BS) might interfere with electronic scales. Can you please enlighten me as to WHY?"</p><p> </p><p>Not quickly, but yes. (Well the cat thng may be an exageration.) Basically, it's either or both static/magnetic fields that have the potential to impact such sensitive instruments as even cheap digital scales have to be. </p><p> </p><p>"Does anyone calibrate lab scales for a living?" </p><p> </p><p>Yes. There are many professional calibration/repair labs for electonic measurement instuments of all types. I worked in that business for some 20+ years, first for the USAF at the Cape and later for NASA. I only did a few scales and that was a LOONG time ago so I have no current specific knowledge of what they are using for a weigth sensening cells but it still has to be either of two main types of strain gages. </p><p> </p><p>Given that .1 grain is only 1/70,000 th of a pound you can see that it requires a LOT of amplification of a tiny signal to see that and read a change of one unit at a time. Electronic amplifier gains of such magnitude, even in solid state and digital chips, are subject to interference from many more things than would be the case at lower levels of gain. The gain will drift easily because very high gain makes for unstable gain. </p><p> </p><p>You also need to know that such high gains from the scale's tiny amplifier means any small changes in the circuit temperature AND/OR power line voltage has the potential (granted, not an automatic certainty in all instruments and good feedback design can help) to change the gain. Thus, digitals need frequent user re-zeroing and calibrations, even while working. What a pain. </p><p> </p><p>Finally, to have even a chance to provide the amp a input usable signal , reading stress on the pan, requires a VERY sensitive pressure cell. Again, great sensitivity means physically quite delicate. Dropping a one ounce weight on a digital scale's pan, from say 6 inches high, would likely damage the cell if not destroy it. But that's my guess, not a fact from personal knowledge. Keep the pan in a digital scale covered at all times if you can.</p><p> </p><p>All that may not help you much but it's about as clear as I can make it for anyone who is not an electronic tech. </p><p> </p><p>As I see it, there are perhaps two valid hopes for a digital over a beam scale. Speed is one, but proper work flow and good work methods will greatly reduce any potential speed advantage. Easy readablity is the other, but putting a beam scale on a shelf at the right height makes it as easy and fast to read as a digital display sitting on the bench. ?? </p><p> </p><p>I have no faith in such digital instuments. My beam scale works too well to spend so much money on something I would never trust. Hope those who have them never have cause to regret it but doubt if many experienced electonic techs would disagree with me.</p><p> </p><p>Am I wrong?</p></blockquote><p></p>
[QUOTE="boomtube, post: 274791, member: 9215"] "I have heard that florescent lights, dimmer switches, mobile phones, RFI and even static electricity from the neighbors cat (another post, another website, no BS) might interfere with electronic scales. Can you please enlighten me as to WHY?" Not quickly, but yes. (Well the cat thng may be an exageration.) Basically, it's either or both static/magnetic fields that have the potential to impact such sensitive instruments as even cheap digital scales have to be. "Does anyone calibrate lab scales for a living?" Yes. There are many professional calibration/repair labs for electonic measurement instuments of all types. I worked in that business for some 20+ years, first for the USAF at the Cape and later for NASA. I only did a few scales and that was a LOONG time ago so I have no current specific knowledge of what they are using for a weigth sensening cells but it still has to be either of two main types of strain gages. Given that .1 grain is only 1/70,000 th of a pound you can see that it requires a LOT of amplification of a tiny signal to see that and read a change of one unit at a time. Electronic amplifier gains of such magnitude, even in solid state and digital chips, are subject to interference from many more things than would be the case at lower levels of gain. The gain will drift easily because very high gain makes for unstable gain. You also need to know that such high gains from the scale's tiny amplifier means any small changes in the circuit temperature AND/OR power line voltage has the potential (granted, not an automatic certainty in all instruments and good feedback design can help) to change the gain. Thus, digitals need frequent user re-zeroing and calibrations, even while working. What a pain. Finally, to have even a chance to provide the amp a input usable signal , reading stress on the pan, requires a VERY sensitive pressure cell. Again, great sensitivity means physically quite delicate. Dropping a one ounce weight on a digital scale's pan, from say 6 inches high, would likely damage the cell if not destroy it. But that's my guess, not a fact from personal knowledge. Keep the pan in a digital scale covered at all times if you can. All that may not help you much but it's about as clear as I can make it for anyone who is not an electronic tech. As I see it, there are perhaps two valid hopes for a digital over a beam scale. Speed is one, but proper work flow and good work methods will greatly reduce any potential speed advantage. Easy readablity is the other, but putting a beam scale on a shelf at the right height makes it as easy and fast to read as a digital display sitting on the bench. ?? I have no faith in such digital instuments. My beam scale works too well to spend so much money on something I would never trust. Hope those who have them never have cause to regret it but doubt if many experienced electonic techs would disagree with me. Am I wrong? [/QUOTE]
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