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Electrical interference with digital scale
- Thread starter 308Loader
- Start date
It can. Radio signals induce currents and voltages in conductors and semiconductors (how a radio receiver picks the signals up). When you are making a very sensitive measurement, you need to have what is called a low signal-to-noise ratio, and those induced currents are added noise in DC circuitry that measures a scale's transducer output. Put enough such current into a semiconductor junction such as the input transistor to an operational amplifier measuring a strain gauge, for example, and it can create an offset voltage that is added to the reading and shows up as a measurement error. The only way to block this is with a Faraday shield, and the higher price scales have them built-in. You can use an aluminum foil-lined box if you need to improvise one.
The other common way radio frequency interference (RFI) gets into electronics is when the noise source, like electric motor brushes in your blender motor or the current surges in a fluorescent lamp fixture, draw that interrupted and surging current through the AC line and they enter a plugged-in power source in your scale. In that instance, using an RF filter on your power connection can help. These are built into computer battery-backup devices, and if you have an old one, even with no battery, you can plug it into the wall and then plug the scale power into it to get that filtering.
But before you go to any of this sort of trouble, make sure you have a problem. Turn off the fluorescent light and motors. Turn off the cell phone to power it down. Wrap it in foil. Take a reading. Bring the phone back and see if the scale reads the same.
The other common way radio frequency interference (RFI) gets into electronics is when the noise source, like electric motor brushes in your blender motor or the current surges in a fluorescent lamp fixture, draw that interrupted and surging current through the AC line and they enter a plugged-in power source in your scale. In that instance, using an RF filter on your power connection can help. These are built into computer battery-backup devices, and if you have an old one, even with no battery, you can plug it into the wall and then plug the scale power into it to get that filtering.
But before you go to any of this sort of trouble, make sure you have a problem. Turn off the fluorescent light and motors. Turn off the cell phone to power it down. Wrap it in foil. Take a reading. Bring the phone back and see if the scale reads the same.
I have two digital scales, both made by PACT, but one is distributed by RCBS. One is in the garage where I reload shotshells; the other is in my reloading room in the house. Both are plugged into an "SL WABER" Powermaster Surge/Noise Suppressor, Model PM 1N.
Of course, I keep them turned off when not in use, but every time we have a storm that causes a power outage, when the power is restored, both scales have been turned on. I also have an Intermatic Panelguard Residential Surge Protection Device on the main circuit breaker panel. Since I'm not certain this activity would not cause permanent damage to the scales, I keep them completely unplugged when not in use.
Another strange situation that is to my benefit is what I suspect the Residential Surge Protector is doing. We have thirty-five standard incandescent 65-watt ceiling floodlights throughout the house and another 18 lighting the periphery outside. In 23 years 5 outside bulbs and 2 inside have burned out and required replacement. In the basement rec room and main room middle floor, we leave 75-watt table lamps on all night from sundown to sunrise that have standard incandescent bulbs as well - and in 23 years I have changed 6 bulbs. Am I correct that the surge protector is keeping the other bulbs alive?
Of course, I keep them turned off when not in use, but every time we have a storm that causes a power outage, when the power is restored, both scales have been turned on. I also have an Intermatic Panelguard Residential Surge Protection Device on the main circuit breaker panel. Since I'm not certain this activity would not cause permanent damage to the scales, I keep them completely unplugged when not in use.
Another strange situation that is to my benefit is what I suspect the Residential Surge Protector is doing. We have thirty-five standard incandescent 65-watt ceiling floodlights throughout the house and another 18 lighting the periphery outside. In 23 years 5 outside bulbs and 2 inside have burned out and required replacement. In the basement rec room and main room middle floor, we leave 75-watt table lamps on all night from sundown to sunrise that have standard incandescent bulbs as well - and in 23 years I have changed 6 bulbs. Am I correct that the surge protector is keeping the other bulbs alive?
@ 308loader google EMI interference then buy a snap on Ferrite bead for a couple of bucks and if you really want to protect your scale buy the least expensive uninterruptible power supply that Best Buy or Amazon sells and plug your scale into that. I think I paid 60 bucks for mine. It won't power the scale for long but that is not why I have it
We have a whole house surge protector and a Generac automatic generator and I still had a computer get fried last summer with a power surge. Now we have all electronics on small UPS's
We have a whole house surge protector and a Generac automatic generator and I still had a computer get fried last summer with a power surge. Now we have all electronics on small UPS's
jetinteriorguy
New member
Yup, that’s why I only use a good beam balance scale for measuring powder charges.
603Country
New member
And I haven’t used my balance beam scale in at least 10 years. RCBS 1500 electronic scale for me.
Never thought much about lighting when my RCBS1500 does not match my old 5-0-5 beam scale.
Just bought some LED 8ft tubes to rid my bench of the fluorescent buzz and will be pulling the ballast out to rewire for the LED tubes soon.
Think I'm going to do a few test weighs both before and after the lamp changes just to if there is a variance.
E.
Just bought some LED 8ft tubes to rid my bench of the fluorescent buzz and will be pulling the ballast out to rewire for the LED tubes soon.
Think I'm going to do a few test weighs both before and after the lamp changes just to if there is a variance.
E.