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TEKNOLOGI
BOLEH PAKAI
Digital Tachometer: Hand-Held Contact Type That Holds Its Reading (Sugiyama, Shimpo, US 4,000,465, 1976)
A hand-held digital tachometer. You press the contact head on its shaft against the end of a turning shaft and push the thumb button; a slotted disk inside chops a light beam into pulses, and the pulses counted in a fixed time, set by a quartz clock, appear in the window as the speed. A latch holds the reading after you take the tachometer away, so you can read it even where you could not see the window while measuring.
Result: a contact tachometer that shows revolutions per unit time and keeps the last reading.
Source: Y. Sugiyama (Shimpo Kogyo), US 4,000,465 (1976). Unknown: the number of holes, the clock, the gate time and the circuit details. Picture: the patent drawing.
Lanjutan
Unknown
Arahan
1
1
Make the housing and measuring shaft
Make the housing and measuring shaft
Make a cylindrical housing to hold in one hand, with a window in its side for the reading and a push button for the power switch where the thumb falls. Run a measuring shaft out of the front end in bearings and fit a contact head on its tip to press against the shaft being measured. Not given: materials, sizes. Ours: aluminium tube, a ball bearing.
Bahan untuk langkah ini:
Tiub aluminium1 housing
Logam tidak diketahui1 measuring shaft
Galas Bebola1 keping
Bahan tidak diketahui1 contact headAlatan diperlukan:
Mesin Pelarik Logam
Gerimit tangan
Dimensi tidak diketahui2
2
Make the pulse generator
Make the pulse generator
Fix a disk on the measuring shaft with a ring of small holes evenly spaced near its edge. Put a light source on one side of the disk and a photodetector on the other: each hole passing makes one pulse. Shape and amplify the pulses. Not given: the number of holes. Ours: an LED and a photodiode.
Bahan untuk langkah ini:
Bahan tidak diketahui1 slotted disk
Pelbagai LED1 light source
Fotodiod (BPW34)1 photodetector
Rintangan1 setAlatan diperlukan:
Gerimit tangan3
3
Build the counting circuit
Build the counting circuit
Divide a quartz oscillator's clock down to gate pulses one unit of time long. Pass the measurement pulses through an AND gate during each gate pulse into a counter. At the start of each gate pulse a reset pulse clears the counter. After the gate pulse ends, the first measurement pulse that arrives triggers a latch pulse that loads the new count into the display. If the head has been taken off the shaft, no pulse arrives, no latch pulse is made, and the display keeps the last reading until the next measurement or until the power is switched off. Not given: the clock frequency and gate time. Ours: logic ICs and a seven-segment display.
Bahan untuk langkah ini:
Papan litar bercetak1 keping
Kristal kuarza1 keping
Pelbagai IC logik1 divider, AND gate, counter, latch, reset
Pemacu Paparan Tujuh Segmen1 keping
Paparan Tujuh Segmen Empat Digit1 keping
Dawai Pateri1 as neededAlatan diperlukan:
Alat pematerian4
4
Power it and measure
Power it and measure
Fit the battery and the thumb button as the power switch. Press the contact head against the end of the turning shaft so it turns with it, push the button, and read the revolutions in the window, now or after you take the tachometer away.
Bahan untuk langkah ini:
Bateri1 keping
Butang tekan1 kepingAlatan diperlukan:
Alat pematerianBahan
15- 1 housingPemegang Tempat
- 1 measuring shaftPemegang Tempat
- Pemegang Tempat
- 1 slotted diskPemegang Tempat
- 1 light sourcePemegang Tempat
- 1 photodetectorPemegang Tempat
- 1 setPemegang Tempat
- 1 kepingPemegang Tempat
- 1 kepingPemegang Tempat
- 1 divider, AND gate, counter, latch, resetPemegang Tempat
- 1 kepingPemegang Tempat
- 1 kepingPemegang Tempat
- 1 as neededPemegang Tempat
- 1 kepingPemegang Tempat
- Pemegang Tempat
Alatan Diperlukan
4- Pemegang Tempat
- Pemegang Tempat
- Pemegang Tempat
- 2 vendors sell this, none ship to you yetPemegang Tempat
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