Difference between revisions of "Precision Pendulum Assembly"

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'''THIS PAGE IS STILL WORK IN PROGRESS'''
 
'''THIS PAGE IS STILL WORK IN PROGRESS'''
  
This page is intended to serve as the assembly instructions for the Precision Pendulum, particularly following the setup developed for the WPA project. This page starts with a brief description of the apparatus and its core components. Then it is followed by the description fo the assembly process which is divided into three core parts: the Mechanical assembly, the electronic controller assembly and the calibration of the setup. An additional step is described for those who want to allow "non-remote" operation (ie: local operation in a museum or common area with public access).  
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This page is intended to serve as the assembly instructions for the Precision Pendulum, particularly following the setup developed for the WPA project. This page starts with a brief description of the apparatus and its core components. Then it is followed by the description of the assembly process which is divided into three core parts: the mechanical assembly, the electronic controller assembly and the setup calibration. An additional step is described for those who want to allow "non-remote" operation (ie: local operation in a museum or common area with public access).  
  
'''Contents'''
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==Order of assembly==
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Although not critical is recommended to follow this recommendation list in order to proper assembly the structure. This list only refer to the main points that shall not be neglected and highlight the most leave-out aspects:
  
#[[Precision Pendulum Assembly: Apparatus Description| Apparatus Description]]
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#Assemble the main structure according to the instructions on page [[Precision Pendulum Assembly: Mechanical assembly| Mechanical assembly]], filling up the tubes with small grained sand ''but'' only to 2/3 of their height after being tight to avoid sand leakage. Conversely they can be taped in the interior with a small cardboard disk.
 +
#Keep the screws loose (only hand tight) during the alignment; only after setting up the complete structure and proper calibration they should be tighten.
 +
#During cable measurements take the fulcrum out of the rail (cable off-centered) in order to measure the exact length by having it on the parallax plane.
 +
#Excite the pendulum by hand very gently to define the exact plane of natural oscillation and use the screw nuts on the launcher to perfectly align the launcher with it direction; before doing it have a flashlight and paper screen on opposite sides of the launcher to perfect align the oscillation plane. With this technique the wire shadow should not move from the center of the screen paper.
 +
# Use the command "laser on" to align the laser; the laser can be focused by rotation the lens on its case if the beam became quite divergent.
 +
#To do the calibration of the shovel movement, use a long displacement such as 300mm to 400mm to reduce systematic errors. Issue in sequence the commands "go to origin 5 5" to read the axes origin reference, then issue "move forward 40 2 2" to slowly move the shovel 400 mm. Lastly take note for the vertical position and maximum position. This 4 values are of extreme importance to calibrate the experiment.
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 +
 
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==Contents==
 +
 
 +
#[[Precision Pendulum Assembly: Apparatus description| Apparatus description]]
 
#[[Precision Pendulum Assembly: Mechanical assembly| Mechanical assembly]]
 
#[[Precision Pendulum Assembly: Mechanical assembly| Mechanical assembly]]
 
#[[Precision Pendulum Assembly: Electrical interfaces| Electrical interfaces]]
 
#[[Precision Pendulum Assembly: Electrical interfaces| Electrical interfaces]]
 +
#[[Precision Pendulum Assembly: Software management| Software management]]
 
#[[Precision Pendulum Assembly: Calibration| Calibration]]
 
#[[Precision Pendulum Assembly: Calibration| Calibration]]
 
#[[Precision Pendulum Assembly: Partners| Partners]]
 
#[[Precision Pendulum Assembly: Partners| Partners]]
 
==Non-remote usage==
 
For local use, the gate system can drive an up/down counter. Currently, we have adopted the Velleman multifunction up/down counter [https://www.velleman.eu/products/view/?id=348233 kit K8035] avaiable off-the-shelf. The connection to the photo-diode is done via the VCC to the UP channel (pin 9) using just the first (R14) 2,2k resistor and eliminating the protection circuit in the transistor's gate (ZD1, R15 and R18).
 
 
The device should operate with  ''Long debounce'' enable. Moreover we can use the regulated power supply (5V) in series with a 33 Ohms resistor to feed the photogate's laser pointing device.
 
 
===Gate system===
 
[[File:photogateholder.jpg|thumb|Photodiode holder forming one side of the photogate - far right - and the laser pointer holder with 3 bolts to adjust the beam focus at left. It is visible the motor and the mass launcher.]]
 
To avoid a long run of the experiment to achieve a reasonable period accuracy readout with a normal chronometer one could use instead of a gated photo-detector connected to an acquisition system or to a precision pulse counter.
 
 
The [[World Pendulum]] design can be easily adapted as it consists on a photodiode mounted in a aluminium (or PVC) holder (20x20x6 mm<sup>3</sup>) with a central 1,5mm hole and a 4mm cavity on the back side(see design) where is fixed the photodiode with a black plastic wax.
 
 
In front of the photodiode, a solid-state laser beam from a normal pointer device is used to trigger the counter once the ball hide the light.
 
 
==Partners==
 
Mechanical structures in suport of high schools replicas have been assembled and constructed with the kind help of CENFIM, Lisbon.
 
[[File:Cenfim_Logo.jpg‎]]
 

Latest revision as of 10:32, 13 February 2020

THIS PAGE IS STILL WORK IN PROGRESS

This page is intended to serve as the assembly instructions for the Precision Pendulum, particularly following the setup developed for the WPA project. This page starts with a brief description of the apparatus and its core components. Then it is followed by the description of the assembly process which is divided into three core parts: the mechanical assembly, the electronic controller assembly and the setup calibration. An additional step is described for those who want to allow "non-remote" operation (ie: local operation in a museum or common area with public access).

Order of assembly

Although not critical is recommended to follow this recommendation list in order to proper assembly the structure. This list only refer to the main points that shall not be neglected and highlight the most leave-out aspects:

  1. Assemble the main structure according to the instructions on page Mechanical assembly, filling up the tubes with small grained sand but only to 2/3 of their height after being tight to avoid sand leakage. Conversely they can be taped in the interior with a small cardboard disk.
  2. Keep the screws loose (only hand tight) during the alignment; only after setting up the complete structure and proper calibration they should be tighten.
  3. During cable measurements take the fulcrum out of the rail (cable off-centered) in order to measure the exact length by having it on the parallax plane.
  4. Excite the pendulum by hand very gently to define the exact plane of natural oscillation and use the screw nuts on the launcher to perfectly align the launcher with it direction; before doing it have a flashlight and paper screen on opposite sides of the launcher to perfect align the oscillation plane. With this technique the wire shadow should not move from the center of the screen paper.
  5. Use the command "laser on" to align the laser; the laser can be focused by rotation the lens on its case if the beam became quite divergent.
  6. To do the calibration of the shovel movement, use a long displacement such as 300mm to 400mm to reduce systematic errors. Issue in sequence the commands "go to origin 5 5" to read the axes origin reference, then issue "move forward 40 2 2" to slowly move the shovel 400 mm. Lastly take note for the vertical position and maximum position. This 4 values are of extreme importance to calibrate the experiment.


Contents

  1. Apparatus description
  2. Mechanical assembly
  3. Electrical interfaces
  4. Software management
  5. Calibration
  6. Partners