LAS_v2
Light Activated Shutter design Version 2 with a little pre amp to reduce hysteresis and allow level setting. It works in the house but will it do the job in the field?
To set it up all the adjustments are put centre. At the activation low low level 'level1' is adjusted until the shutter just opens. After setting the activation level the 'gain' is adjusted so there is a suitable difference between the dark activation (shutter open) and the light activation (shutter closed). Level 2 adjustment can tweak the low light activation but can only be used over a small part of its middle range. The gain adjuster can only be used over a short range due to design limitations. To overcome the gain limitation the level 2 adjustment needs to be low impedance and the gain adjuster should not be tied to 0V.
Alternatively the pre amp could be replaced with a positive feedback hysteresis amplifier.
LAS_v2
Light Activated Shutter design Version 2 with a little pre amp to reduce hysteresis and allow level setting. It works in the house but will it do the job in the field?
To set it up all the adjustments are put centre. At the activation low low level 'level1' is adjusted until the shutter just opens. After setting the activation level the 'gain' is adjusted so there is a suitable difference between the dark activation (shutter open) and the light activation (shutter closed). Level 2 adjustment can tweak the low light activation but can only be used over a small part of its middle range. The gain adjuster can only be used over a short range due to design limitations. To overcome the gain limitation the level 2 adjustment needs to be low impedance and the gain adjuster should not be tied to 0V.
Alternatively the pre amp could be replaced with a positive feedback hysteresis amplifier.