Externet Posted October 30, 2011 Share Posted October 30, 2011 Hi. How can the exterior (as in a yard) ambient light just after sunset be focused/directed to a photosensor in order to delay its action that turns on some lights at night ? The sensing device is not adjustable for threshold of operation. I have several plano-convex and bi-convex lenses; from 1" to 6" diameter. With a defined light source as the sun disc, focusing it to the photosensor is no problem -when coaxial- but with diffuse light it is another story. Suggestions, please ? Link to comment Share on other sites More sharing options...
insane_alien Posted October 30, 2011 Share Posted October 30, 2011 you could maybe use a fisheye lense to gather light from a large portion of sky. its not going to be very efficient but really, there isn't a whole lot of light to be collecting. Link to comment Share on other sites More sharing options...
DrRocket Posted October 30, 2011 Share Posted October 30, 2011 Hi. How can the exterior (as in a yard) ambient light just after sunset be focused/directed to a photosensor in order to delay its action that turns on some lights at night ? The sensing device is not adjustable for threshold of operation. I have several plano-convex and bi-convex lenses; from 1" to 6" diameter. With a defined light source as the sun disc, focusing it to the photosensor is no problem -when coaxial- but with diffuse light it is another story. Suggestions, please ? Amplify the photosensor -- turn up the gain. Your problem is more easily solved with electronics than with optics. Link to comment Share on other sites More sharing options...
md65536 Posted October 30, 2011 Share Posted October 30, 2011 Hi. How can the exterior (as in a yard) ambient light just after sunset be focused/directed to a photosensor in order to delay its action that turns on some lights at night ? The sensing device is not adjustable for threshold of operation. I have several plano-convex and bi-convex lenses; from 1" to 6" diameter. With a defined light source as the sun disc, focusing it to the photosensor is no problem -when coaxial- but with diffuse light it is another story. Suggestions, please ? I wanted to do the same thing and I solved the problem electronically. The photosensor is probably a photoresistor. The more light that shines on it, the lower the resistance. All you have to do is lower the resistance, and that should have the same effect as shining more light on it. The way I did this was to add another photoresistor in parallel. It's very quick and dirty but it worked adequately for me. I happened to have a few lying around. If you don't, you might try using a normal resistor, but I'm not sure how effective it would be. Or a variable resistor, or even a combination of several of these. Another photoresistor should be better because it behaves like the one that's already there (I suppose it's like doubling the surface area of the original photoresistor). I also had the additional photoresistor outside of the main box so it could be tweaked by orienting it differently. Link to comment Share on other sites More sharing options...
Klaynos Posted October 30, 2011 Share Posted October 30, 2011 Electronics would be easy... but... A large parabolic mirror, would probably gather the most light easily... Link to comment Share on other sites More sharing options...
Externet Posted October 30, 2011 Author Share Posted October 30, 2011 Nope on electronics adjustments -----> www.fairchildsemi.com/ds/QS/QSE158.pdf If no lensing is promising... Parabolic mirror could work. Thanks Link to comment Share on other sites More sharing options...
ewmon Posted October 30, 2011 Share Posted October 30, 2011 (edited) You can effectively adjust its threshold by adding enough light (perhaps a tiny LED etc), thus tricking the device into believing that it's earlier in the evening. The man who taught me this sort of trick was the man who went on to invent an impedance-based method for controlled cryosurgery of malignant tumors. Edited October 30, 2011 by ewmon Link to comment Share on other sites More sharing options...
StringJunky Posted October 31, 2011 Share Posted October 31, 2011 (edited) You could put another adjustable inline dusk-to-dawn sensor switch in the electrical path before the sensor/light. Your sensor/light won't come on until your new switch turns on at your desired setting. They don't seem expensive here in the UK. http://www.lightingstyles.co.uk/Exterior-garden-lighting/PIR-detection-sensor-lights/Electronic_sunset_timer_switch.htm Edited October 31, 2011 by StringJunky Link to comment Share on other sites More sharing options...
Externet Posted October 31, 2011 Author Share Posted October 31, 2011 That was brilliant, ewmon. Thanks to all. Link to comment Share on other sites More sharing options...
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