Found these by accident. Looks like they could be useful on a layout.
Instuctions are in the review section.
Thanks South Penn, I put that into an eBay search. I have what looks like the same one on the way for $2.88.
http://www.ebay.com/itm/252592538946?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
When the slow boat from China gets here I test it and do a follow up post.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melv
Thanks Mel!
I’ve been building my own optical detectors but at that price it’s looking pretty good. My built ups cost about $1.50 each and I’m not using a relay, this one is assembled in a neat package with a relay.
I had plans for building up some of my own with relays for some other projects, this just might be the answer.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
Check the comments in the reviews about chattering around the set point. Could be a problem with some applications.
Joe
This unit has a Songle relay, I haven’t used them before so that is an unknown.
I have a couple dozen Aromat relays in my control panel and I have to listen carefully to hear them. That can also be a problem when trouble shooting.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogsp
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
Randy
My reason for ordering one is for the convent packaging. After a good test I’m going to try a IR detector in it. If that works without much dinking around I’m going to order more of them. I use IR detection all over my layout and these packages look like very nice replacements for my home brews.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield
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.
–Randy
Randy
Thanks again Randy, I’ve got a drawer full of resistors so with your help I’m in business when it gets here.
I did a copy and paste of his article and picture.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California