My new nightlight has a cds cell feeding a comparator with a time constant, so it doesn't turn on immediately when the cell is covered. Only problem is that if you put it too close to something, you get a relaxation oscillator:
Patent it ;-) ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
"bitrex"
** Yeah - the light sensor must not be illuminated by the same light it controls.Just as dumb is putting the sensor in direct sun light and then controlling a hallway light that is in deep shade.
That *was* the case in the block where I live, the natural light level in the hallways fell to near darkness (about 0.5lux) before the sensor brought the fluoro lighting on. Similarly in the mornings, the lighting went off long before there was any daylight in the halls.
The sensor unit has no accessible adjustment, so I painted several coats of white acrylic over the window until it worked as desired.
.... Phil
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Already exists, it's called a UJT :^)
Tim
that's just irritating.
seems incredibly stupid to NOT use hysteresis instead of time constant. Perhaps, what you're seeing is an 'integration' effect that appears to look like a time constant. ...just food for thought.
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