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Bathroom Scale: Four Flat Load Cells Between Two Plates (Angel, 1991)
A floor scale only as thick as two plates. Four flat load cells sit in the corners between a base and a top plate; their strain gauges are wired into one bridge, so the signal is the sum of the four loads wherever you stand.
Result: a low digital bathroom scale reading in pounds or kilograms. The patent gives under 0.05 % non-linearity, hysteresis and non-repeatability, and under 0.1 % error from off-centre loads; its feet let it stand on thick carpet.
Source: S. Angel, US Patent 4,993,506 (1991). Unknown: the plate material and size, the maximum load, and the circuit. Ours: ebonite for the hard rubber, epoxy, the amplifier and display parts. Picture: patent drawing (Fig. 5).
고급
2 days
안내
1
1
Mount the four load cells
Mount the four load cells
Put one load cell in each corner of the rigid base plate. Screw each one down to small flat raised pads on the plate. Place the pads away from the edge of the cell's beam, so that fixing the cell does not change its sensitivity. Under each cell, tap two holes through the base for the overload screws. Not given: the plate material and size.
이 단계의 재료:
로드셀4 개
저울 밑판과 윗판1 base and top plate
기계 나사8 cell screws필요한 도구:
나사내기 탭·다이스 세트
드라이버 세트
알 수 없는 치수2
2
Wire one bridge and the readout
Wire one bridge and the readout
Each cell's two gauges are half a Wheatstone bridge. Join the four halves into one full bridge, one half at each corner, so the bridge gives a signal in step with the sum of the four loads. The signal is amplified, turned into numbers by an analog-to-digital converter, worked into pounds or kilograms and shown on a display. Put the electronics and batteries in the space between the plates. Not given: the circuit. Ours: an op-amp and a segment LCD.
이 단계의 재료:
연산 증폭기 IC1 amplifier
아날로그-디지털 변환기1 개
세그먼트 액정 패널1 개
전지1 as the circuit needs
배선용 전선1 as needed
땜납 선1 a little필요한 도구:
인두3
3
Fit the top plate on hard rubber pads
Fit the top plate on hard rubber pads
Glue four flat round pads of a rigid but slightly yielding material, such as hard rubber, under the top plate. Give each pad small round studs that snap into the two load holes of its cell, so the weight goes in at the centres of those holes. The pads soften impacts when something is dropped on the scale and take up sideways forces as the top plate bends. The snaps let the top plate be pulled off for repairs. Ours: ebonite and epoxy.
이 단계의 재료:
에보나이트 봉1 four pads
2액형 에폭시1 a little필요한 도구:
쇠톱(핵소)4
4
Fit the feet
Fit the feet
Under the base, below each cell, fix a shallow foot of flexible material such as hard rubber, rounded underneath. Put its lowest point exactly below the centre of the cell's beam: the floor then pushes up at the beam's centre without bending it, and the scale works on thick carpet or uneven floors. Ours: ebonite.
이 단계의 재료:
에보나이트 봉1 four feet2액형 에폭시1 a little필요한 도구:
쇠톱(핵소)5
5
Set the overload stops
Set the overload stops
Load the scale to its maximum capacity. Turn the short screws in from below until they just touch the arms of each cell's loading element, then lock them with adhesive. Any heavier load now rests on the screws instead of bending the cells further. Not given: the maximum capacity. Ours: calibration weights and epoxy.
이 단계의 재료:
기계 나사8 overload screws2액형 에폭시1 a little필요한 도구:
교정용 분동 세트드라이버 세트재료
11- 4 개플레이스홀더
- 1 base and top plate플레이스홀더
- 8 overload screws플레이스홀더
- 1 amplifier플레이스홀더
- 1 개플레이스홀더
- 1 개플레이스홀더
- 1 as the circuit needs플레이스홀더
- 1 as needed플레이스홀더
- 1 a little플레이스홀더
- 1 four feet플레이스홀더
- 3 a little플레이스홀더
연결된 블루프린트 재료
이 블루프린트로 만드는 것
CC0 퍼블릭 도메인
이 블루프린트는 CC0로 공개되었습니다. 어떤 목적으로든 자유롭게 복사, 수정, 배포 및 사용할 수 있습니다.
제품 구매를 통해 메이커를 지원하세요. 판매자가 설정한 메이커 커미션 을 받거나, 이 블루프린트의 새로운 반복을 만들어 연결로 포함시킬 수 있습니다.