What is 'normal' startup ?

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What is 'normal' startup ?

Post by forum_admin » Sat Apr 30, 2016 1:28 pm

The startup of the BST camera core in Argus 2 (and also Argus 3) can cause concern when a camera in an unknown state is first turned on. So, what is normal ?

This is a normal startup for a BST camera.
Descriptions and observations in normal text, what the camera is doing in [.....]

Turn on, initial current surge
[Charges up capacitors, there's lots in a BST core]
Current slowly rises, often no thermal image or perhaps appears behind a 'net curtain' effect.
Video out and camera display will initially be the EEV 'splash' screen, then go to show the thermal image.

[Camera now tries to control the sensor temperature using a peltier device. Takes 1 - 3 minutes]
Image becomes clearer, often with there are waves of 'twinkling' across the image, may appear and disappear a few times
Current reduces.

[Sensor reaches temperature, around 30 - 35°C]
Image clear

The peltier surge adds about 400mA (at 10V input) while the initial spike can be 2A (again 10V input) so may just hit the current foldback on an external supply. it will also drop the battery voltage on near flat cells or low grade primary cells, and can be enough to turn the camera off again.

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