Ushirikiano
SANAA
UREMBO NA USTAWI
UJANJA
UTAMADUNI NA HISTORIA
BURUDANI
MAZINGIRA
CHAKULA NA VINYWAJI
UHANDISI WA KINYUME
SAYANSI
MICHEZO
TEKNOLOJIA
VAZI
Digital Caliper: Capacitive Scale and Slider with Two-Chip Electronics (Baxter and Buehler, Starrett, 1986)
A six-inch caliper that reads out on a display. Under the slide, a strip of etched copper bars runs along the beam. Electrodes on the slider pass a signal through the bars by capacitance, and the slider's electronics count the bars crossed and work out the position in between.
Result: a digital caliper reading in inches or millimetres, repeatable to a ten-thousandth of an inch, with floating zero, peak hold and high/low limits. It runs on two 1.5 V cells at 10-50 microamps.
Source: L. K. Baxter and R. J. Buehler (L. S. Starrett Co.), US Patent 4,586,260 (1986). Unknown: the metal of the beam, slide and rod, their dimensions, the processor's program, and how the chips and display are made. Ours: the etchant, photoresist and glue. Picture: Wikimedia Commons.
Juu
2 days
Maagizo
1
1
Etch the scale
Etch the scale
Etch the scale pattern onto a strip of copper-clad epoxy fibreglass with photoresist and etchant. Each copper bar is 0.40 inch long, with a wider centre 0.12 inch long and two ends 0.14 inch long. Space the bars on 0.05 inch centres: the centres sit 0.004 inch apart, the ends 0.025 inch apart. Run the pattern the full length of the scale. Ours: dry film resist and ferric chloride.
Vifaa kwa hatua hii:
Bamba tupu la mzunguko (lililofunikwa shaba)1 strip, length of the beamZana zinazohitajika:
Filamu kavu ya kupinga mwanga
Myeyusho wa kloridi ya feriki
Glavu zinazostahimili kemikali2
2
Fix the scale into the beam
Fix the scale into the beam
The beam is a metal bar with the fixed outside and inside jaws at one end, a wide shallow channel in its face and a second channel along its back. Fix the scale permanently into the face channel, copper up. The patent allows etching before or after this step. Not given: the metal, the dimensions and how the scale is fixed. Ours: epoxy.
Vifaa kwa hatua hii:
Upau wa kalipa1 with integral jaws
Epoksi ya Sehemu Mbili1 a littleZana zinazohitajika:
Vipimo visivyojulikana3
3
Fit the parts to the circuit
Fit the parts to the circuit
The circuit is one folded piece: a double-sided slider board joined by a flexible hinge to a circuit board. Its bottom face has two pickup electrodes, 0.750 x 0.110 inch and 0.0625 inch apart. On each side of them is an interdigitated transmitter array: fingers 0.115 inch long on 0.025 inch spacing, opening to 0.0375 inch at the centre. On the circuit board, solder or wire-bond the two chips: an NEC uPD7503 3 V processor (768 bits RAM, 2 kB ROM) and a CMOS gate array. Then fit the LCD, the 100 kHz crystal, the integrating capacitor and the MODE and SET buttons. Not given: the processor's program. Ours: a capacitor from a kit.
Vifaa kwa hatua hii:
Bodi ya saketi gumu-nyumbufu1 slider board + circuit board
Saketi iliyounganishwa2 uPD7503 CPU, CMOS gate array
Paneli ya LCD ya sehemu1 5 digits
Kioo cha kwatsi1 100 kHz
Seti ya Kapasita1 one integrating capacitor
Kitufe cha kubonyeza2 MODE, SET
Waya wa Lehemu1 a littleZana zinazohitajika:
Chuma cha kulehemia4
4
Build the slide
Build the slide
The slide frame wraps the back and edges of the beam and carries the movable jaws. Fix it to the depth rod, which runs in the back channel of the beam; the rod's free end is the depth gauge. Put the moulded plastic housing between the frame ends. Fasten two metal wear strips under the slider board, one on each side of the scale. They ride on the beam and connect the board's copper to it. Not given: the metal and sizes.
Vifaa kwa hatua hii:
Fremu ya kitelezi1 with jaws
Metali isiyojulikana1 depth rod and two wear strips
Kasha la kitelezi1 kipandeZana zinazohitajika:
Vipimo visivyojulikana
Seti ya bisibisi sahihi5
5
Assemble and check
Assemble and check
Fold the circuit into the housing recess, slider board facing the scale, and screw it to the frame. The electrodes must lie parallel to the scale bars at every point of travel. Put the two 1.5 V cells (the patent says 'zinc oxide') in the battery pockets of the circuit. The display shows five digits, a ten-thousandths bar graph, a minus sign and 'mm', plus PEAK, LOW, HIGH and LIMIT. Ours: check the reading against a vernier caliper.
Vifaa kwa hatua hii:
Skrubu za mashine2 vipande
Betri ya kifungo ya volti 1.52 vipandeZana zinazohitajika:
Seti ya bisibisi sahihi
Kalipa ya VernierVifaa
15- 1 strip, length of the beamKishikilia Nafasi
- 1 with integral jawsKishikilia Nafasi
- 1 a littleKishikilia Nafasi
- 1 slider board + circuit boardKishikilia Nafasi
- 2 uPD7503 CPU, CMOS gate arrayKishikilia Nafasi
- 1 5 digitsKishikilia Nafasi
- 1 100 kHzKishikilia Nafasi
- 1 one integrating capacitorKishikilia Nafasi
- Kishikilia Nafasi
- 1 a littleKishikilia Nafasi
- 1 with jawsKishikilia Nafasi
- 1 depth rod and two wear stripsKishikilia Nafasi
- 1 kipandeKishikilia Nafasi
- 2 vipandeKishikilia Nafasi
- 2 vipandeKishikilia Nafasi
Zana Zinazohitajika
7- Kishikilia Nafasi
- Kishikilia Nafasi
- Kishikilia Nafasi
- Kishikilia Nafasi
- 2 vendors sell this, none ship to you yetKishikilia Nafasi
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- Kishikilia Nafasi
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