|
Show content only (no menu, header)
Support frame, mouting
 |
Side view of the system
The system is mounted on the side of a building at the Mauna Loa Observatory. The mount and camera are inside the large white cylinder, which is mounted to tbe building with an aluminum frame. The total volume of the cylinder is 0.67 m diameter, 0.3 m tall. The outer part is a white cylinder designed to reduce wind on the camera and mount.
|
 |
Front view of the system
Mount and camera body are seen inside the cylinder. They are coverered by while silicone rubber for protection against weather and sunlight. The camera is parked, with the lens pointing down.
|
Electronics
 |
Electronics are mounted on a metal plate (Old configuration: Dec 2010 - Jul 2011)
The I/O modules are at the top of the pictures (from left to right: relay board, analog I/O, digital I/O), power supplies are at the bottom.
|
I/O modules
Custom electronics I/O is performed with 3 commercial RS232 cards. The computer communicates with the cards through USB with a USB to RS232 converter.
Communication with the modules is described in the following 2 documents;
- Stackable RS-232 Communications [pdf]
- Host Programming Guidelines [pdf]
Temperature sensors
10k thermistors are used to sense temperature.
Using Wheatstone bridge, with 10k resistors (Rx), 5V excitation voltage.
V = E ((R2/(R1+R2)) - Rx/(Rx+R3))
Using Wheatstone bridge + resistor R4 in series with bridge.
V = E1 ((R2/(R1+R2)) - Rx/(Rx+R3))
with
E1 = E (R1+R2)//(R3+Rx) / (R4 + (R1+R2)//(R3+Rx))
(R1+R2) // (R3+Rx) = 1/(1/(R2+R3) + 1/(R3+Rx))
With E=5V, R1=R2=R3=R4=6.666k :
V = 5V (0.5 - Rx/(Rx+10k))
With the -10V to -8V voltage range setting on the WTAIN-M, the resolution is 22 uV = 0.18 Ohm on Rx at 0C = 0.4 mK (435 Ohm / C).
With the -0.6V to +0.6V voltage range setting on the WTAIN-M, the corresponding temperature range is -10C to +8.5C.
Page content last updated:
27/06/2023 06:35:52 HST
html file generated 27/06/2023 06:34:44 HST
|
