I put a large cup hook into one of my doorframes for using a very similar luggage scale. It lets you get accurate readings for shipping packages. It also leaves your hands free to let it zero properly before hanging things on the hook. The tare function is incredibly useful on all scales. It lets you weight a container, then "tare" (zero its weight out) so that you can then use it to hold stuff being weighed without it actually adding to the weighing result. It also lets you zero something that you're already weighing so you can see the weight of what you are adding to it.
The strain gauge is basically just a single resistor that changes its value based on how much it has been bent. A few people have mentioned that it could be a Wheatstone Bridge, but based on the I+, I-, E+. and E- symbols, im fairly certain that its just a four point probe basically. there is a constant current going though the I terminals, and as the resistor changes value, the voltage changes. This method is also cheaper than using a Wheatstone Bridge. Hope that helps! Love your videos :D
How is a constant current source cheaper than 3 matched resistors (or two if using half bridge)? I also don't see why they have bothered with four wires if there is no wheatstone bridge there. The resistance in the wires shouldn't matter much in this set-up. E+ and E- likely stands for excitation voltage. I don't know why I+ and I- is chosen though for a wheatstone bridge. But I like your thinking. How will your method cope with the very minute changes of only milliohms that is normal for a stain gauge? A change from 350.00ohms to 350.01ohms can be very hard to detect even for a wheatstone bridge.
lollandster This is a 2£ product, I don't think too much attention to precision went into this. Also, a 4 wire resistance measurement is a lot easier to implement into a mass produced ASIC COB.
A 4-wire resistance measurement is also a reasonable suggestion, and is ideal for measuring low resistance values where the resistance of the wires and connections are significant. And it doesn't have to be a constant current source if the current is measured, you just need a small uncertainty in current. The way to tell which it is, is to measure the voltage across the I terminals, and then across the E terminals, with the device on and with no load. If the I voltage is comparable to, and slightly greater than that across the E terminals, then it is a 4-wire measurement circuit. But if the E voltage is very small in comparison to the I voltage, then it's a Wheatstone bridge.
Another fascinating thing about these generic scales is the calibration technique. You set the unit to calibration mode (not sure how it's done on the luggage scales) and it automatically calibrates the zero weight, then you add a known fixed weight and it calibrates to that and everything else in between comes out accurately.
Clive, fancy seeing you here. I'm trying to find more people like you but who take apart digital electronics and try to figure stuff out about it by finding UART or JTAG connectors etc.. Can you recommend anyone?
I think Julian will probably agree with me in saying that mikeselectricstuff is king for DEEP teardowns including tapping into serial ports to expose Linux style operating systems within products.
bigclivedotcom that's exactly what I'm after. Thanks for your help, and keep up the great work with your own videos! My girlfriend recognises your voice these days with a roll of her eyes :-)
Another interesting video. I wish I had had your RUclips videos thirty years ago when I had the time to tinker and build interesting projects! (As it is, I watch them in the hope that they will fill in some gaps in my electronics knowledge and that maybe some day I will have the time to build some cool stuff...)
10 grams would be kg in just 2 decimals ... but in the video you cans see the 3'rd reading out data (that would be grams) ... something doesn't match with the description on ebay.
Tare just sets the zero point for your current session on the scale. So if you have like sand or something you want to weigh, put the bag on first without sand, hit tare to zero it out, then add sand. Now you have weight of sand only. Sand sans bag, har har
In my language tare is called "tara" - an old word which means the weght of the packaging of something. So from the total weight you substract "tara" and get the net weght :)
Havnt finished the video yet but the tare function always clears the scale to zero allowing you to add say a cup, hit tare to clear the weight allowing you to weigh whatever you place in the cup without the cups added weight!!
Is it possible to adjust the scale ? I have ordered 2 pcs. and they show different mesuaring in "gramms". 1220 & 1355 difference is 135 gr. 2910 & 3045 difference is 135 gr. 5755 & 6065 difference is 310 gr. I'm dissappointed !!!
You can calibrate the temperature: 1) push the power to turn it on 2) long push 'unit' to display the temperature 3) push and hold 'power', then simultaneously push 'unit' to increase the temperature or push 'tare' to decrease
Julian Ilett too bad :-( Seems like the manufacturer changed things. My scale is almost five years old, without the LED and just two digits after the dot and 20g resolution.
Lol, Julian Tare is used to zero the scale , say you weigh rice it won't fit on the scale or go all over so you use a bowl and set bowl on scale then press Tare the scale will then zero itself again and you can accurately weigh "rice" I may have sold some herbs in high school don't judge me
I have a slightly different scale, which only shows two decimal places and the three buttons are arranged in a smiley face. It has a metal rod going through, instead of the "rope" yours has. But internally it has a very similar PCB and LCD. I have no idea how that strip/LCD works, how is the connection made and what about pin alignment?
Okay, did that. I assume this uses the version where the conductive areas are small but there are many of them, so that whatever pattern is used as an input is presented pretty much exactly on the other side, so alignment is not essential, as long as the strip covers all pads?
YensR That's hard to tell. The strip can't really move anywhere in this scale, so it is "autoaligned", and the pads are huge with big gaps in beween. My guess is that strips with many thin layers are more expensive than a few thick ones (never bought one though ;) ). And cheap is definitely a priority here. If the conductive and nonconductive parts are the same color (often they aren't) sometimes you can tell by a slightly different reflectivity in the right light or as last measure, measure.
From when I was working the tare weight was taken with scale empty then one item was check (to get a reading of one item) then many items could be weighed ie. screws and the tare weight would be taken away (usually by the scale) and you would know you had 132 of the screws. The people in the packing dept. check this the first time they got the new machine and found it was 99.99% correct. This speeds up shipping and lowers cost. This is how I was told it worked. (See Wikipedia - Tare weight)
, can you weight a bag of sweets and test the low range accuracy or a known weight of something? {sorry for double post, youtube comments are hanging up for me tonight}
i did giggle at the funny noise you made at ruclips.net/video/q-T5PC6iDLA/видео.html#t=240 , i have a kenwood ts-711e ham radio made 20 odd yrs ago and the front panel buttons are exactly the same as those on the scale
I put a large cup hook into one of my doorframes for using a very similar luggage scale. It lets you get accurate readings for shipping packages. It also leaves your hands free to let it zero properly before hanging things on the hook.
The tare function is incredibly useful on all scales. It lets you weight a container, then "tare" (zero its weight out) so that you can then use it to hold stuff being weighed without it actually adding to the weighing result. It also lets you zero something that you're already weighing so you can see the weight of what you are adding to it.
The strain gauge is basically just a single resistor that changes its value based on how much it has been bent. A few people have mentioned that it could be a Wheatstone Bridge, but based on the I+, I-, E+. and E- symbols, im fairly certain that its just a four point probe basically. there is a constant current going though the I terminals, and as the resistor changes value, the voltage changes. This method is also cheaper than using a Wheatstone Bridge. Hope that helps!
Love your videos :D
How is a constant current source cheaper than 3 matched resistors (or two if using half bridge)? I also don't see why they have bothered with four wires if there is no wheatstone bridge there. The resistance in the wires shouldn't matter much in this set-up. E+ and E- likely stands for excitation voltage. I don't know why I+ and I- is chosen though for a wheatstone bridge.
But I like your thinking. How will your method cope with the very minute changes of only milliohms that is normal for a stain gauge? A change from 350.00ohms to 350.01ohms can be very hard to detect even for a wheatstone bridge.
lollandster This is a 2£ product, I don't think too much attention to precision went into this. Also, a 4 wire resistance measurement is a lot easier to implement into a mass produced ASIC COB.
A 4-wire resistance measurement is also a reasonable suggestion, and is ideal for measuring low resistance values where the resistance of the wires and connections are significant. And it doesn't have to be a constant current source if the current is measured, you just need a small uncertainty in current.
The way to tell which it is, is to measure the voltage across the I terminals, and then across the E terminals, with the device on and with no load. If the I voltage is comparable to, and slightly greater than that across the E terminals, then it is a 4-wire measurement circuit. But if the E voltage is very small in comparison to the I voltage, then it's a Wheatstone bridge.
Another fascinating thing about these generic scales is the calibration technique. You set the unit to calibration mode (not sure how it's done on the luggage scales) and it automatically calibrates the zero weight, then you add a known fixed weight and it calibrates to that and everything else in between comes out accurately.
Clive, fancy seeing you here. I'm trying to find more people like you but who take apart digital electronics and try to figure stuff out about it by finding UART or JTAG connectors etc.. Can you recommend anyone?
I think Julian will probably agree with me in saying that mikeselectricstuff is king for DEEP teardowns including tapping into serial ports to expose Linux style operating systems within products.
bigclivedotcom that's exactly what I'm after. Thanks for your help, and keep up the great work with your own videos! My girlfriend recognises your voice these days with a roll of her eyes :-)
Jin is a unit of weight used in China. Is is 500 g and is used for all everyday weights. The character is 斤.
Another interesting video. I wish I had had your RUclips videos thirty years ago when I had the time to tinker and build interesting projects! (As it is, I watch them in the hope that they will fill in some gaps in my electronics knowledge and that maybe some day I will have the time to build some cool stuff...)
10 grams would be kg in just 2 decimals ... but in the video you cans see the 3'rd reading out data (that would be grams) ... something doesn't match with the description on ebay.
i wonder how the other scales work? the tiny ones they use for gold and certain white powders?
Neat. I like these teardowns of cheap chinese stuff, just to see whats inside and how they produce these things at such a cheap price.
Tare just sets the zero point for your current session on the scale. So if you have like sand or something you want to weigh, put the bag on first without sand, hit tare to zero it out, then add sand. Now you have weight of sand only. Sand sans bag, har har
In my language tare is called "tara" - an old word which means the weght of the packaging of something. So from the total weight you substract "tara" and get the net weght :)
Thanks again! Love the videos.
Tkanks
10g minimum weight.
You have Clas ohlson in the uk? Did not know that... :) Nice video as allways.
Havnt finished the video yet but the tare function always clears the scale to zero allowing you to add say a cup, hit tare to clear the weight allowing you to weigh whatever you place in the cup without the cups added weight!!
Is it possible to adjust the scale ? I have ordered 2 pcs. and they show different mesuaring in "gramms".
1220 & 1355 difference is 135 gr.
2910 & 3045 difference is 135 gr.
5755 & 6065 difference is 310 gr.
I'm dissappointed !!!
You can calibrate the temperature:
1) push the power to turn it on
2) long push 'unit' to display the temperature
3) push and hold 'power', then simultaneously push 'unit' to increase the temperature or push 'tare' to decrease
Unfortunately, that doesn't seem to work on this one. I guess there must be a calibration menu somewhere on this device, but I've not found it yet :(
Julian Ilett
too bad :-(
Seems like the manufacturer changed things. My scale is almost five years old, without the LED and just two digits after the dot and 20g resolution.
Can it display more than 10kg ?
Lol, Julian Tare is used to zero the scale , say you weigh rice it won't fit on the scale or go all over so you use a bowl and set bowl on scale then press Tare the scale will then zero itself again and you can accurately weigh "rice" I may have sold some herbs in high school don't judge me
I have a slightly different scale, which only shows two decimal places and the three buttons are arranged in a smiley face. It has a metal rod going through, instead of the "rope" yours has. But internally it has a very similar PCB and LCD. I have no idea how that strip/LCD works, how is the connection made and what about pin alignment?
Search for "zebra strip". It's a brand name. In essence it's alternating conductive and non conductive rubber layers.
Okay, did that. I assume this uses the version where the conductive areas are small but there are many of them, so that whatever pattern is used as an input is presented pretty much exactly on the other side, so alignment is not essential, as long as the strip covers all pads?
YensR
That's hard to tell. The strip can't really move anywhere in this scale, so it is "autoaligned", and the pads are huge with big gaps in beween. My guess is that strips with many thin layers are more expensive than a few thick ones (never bought one though ;) ). And cheap is definitely a priority here.
If the conductive and nonconductive parts are the same color (often they aren't) sometimes you can tell by a slightly different reflectivity in the right light or as last measure, measure.
superdau Cheers, will keep an eye open for these.
I bought exactly the same one in Taiwan!
if it had a Wheatstone Bridge another sensor should be on the other side of the metal bar
From when I was working the tare weight was taken with scale empty then one item was check (to get a reading of one item) then many items could be weighed ie. screws and the tare weight would be taken away (usually by the scale) and you would know you had 132 of the screws. The people in the packing dept. check this the first time they got the new machine and found it was 99.99% correct. This speeds up shipping and lowers cost. This is how I was told it worked. (See Wikipedia - Tare weight)
Can I just give you my eBay and PayPal logon details so you can just order double the same things you get to play with :)
, can you weight a bag of sweets and test the low range accuracy or a known weight of something? {sorry for double post, youtube comments are hanging up for me tonight}
have a link to buy?
Joe Lycett 🤔
i did giggle at the funny noise you made at ruclips.net/video/q-T5PC6iDLA/видео.html#t=240 , i have a kenwood ts-711e ham radio made 20 odd yrs ago and the front panel buttons are exactly the same as those on the scale
I thought clas ohlson was a Norwegian thing...