Found these by accident. Looks like they could be useful on a layout.
Instuctions are in the review section.
Thanks Mel!
Check the comments in the reviews about chattering around the set point. Could be a problem with some applications.
Joe
JoeinPA Check the comments in the reviews about chattering around the set point. Could be a problem with some applications. Joe
I'm beginning to realize that aging is not for wimps
SHould be ok as long as there is a strong contract between the amount of light hitting the photoresistor when open compared to when blocked - having light overhead if burying the sensor between the rails, or a light source if putting it horizontally across the rails. It looks like about as simple a circuit as you cna get, so if there is some itermediate amount of light falling on the sensor it couldhave precisely the resistence for the transistor to turn on but in the process that slightly alters things so it falls below (or above) the threshold and it turns off again. Always a potential hazard using a photoresistor as a light/dark detector. There are ways to make a slightly more complex circuit that will trigger and stay triggered with a decent dead band around the activation point but of course that will cost more than $2.88.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
So much for that message, the Amazon comments answered everything. Seems like it's an easy fix to prevent the chattering, looks like they used a simple comparator and you just need to add a feedback resistor to add the dead band. One guy even posted a picture of how he did it. The picture of the product on Amazon is exactly the same as the one on eBay, so I'm sure you got the exact same item.