Does anyone have a simple, cheap circuit for light sensing diodes? I need detectors for hidden staging tracks when the tracks are dead.
Thanks,
Michael
there literally hundreds out there , most do use an opamp to differentiate on / off ...
use google to find an image to your liking ...
cadmium sulphied (CDS) cells in series with a LED can work as a simple indicator. These on ebay claim to have a light resistance of ~200 Ohm a dark resistance of ~1M. (you may need to add an extra resistor in series.
can be mounted on the track between the rails with a good light source above.
greg - Philadelphia & Reading / Reading
It doesn’t get much easier than one of these.https://www.ebay.com/itm/Photoresistor-relay-control-module-optical-switch-light-sensor-module-DC12V/371659840411?epid=2184576584&hash=item5688a71b9b:g:oEwAAOSwzXJb-0mgMel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
If all you just need is a simple indicator the Obstacle Avoidance Detection Sensor Module would work. As it’s an Arduino module it is powered by 5 volts.https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Obstacle+Avoidance+Detection+Sensor+Module&_sacat=0
These detection modules work very good and the price is right too.Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
http://www.azatrax.com/ir-model-train-detector.html
Made for what you are trying for. A bit more expensive, but designed for the job.
I put them at the ends of my staging track to show when to stop.
James in Texas