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Offline 3030guy  
#1 Posted : 10 April 2023 10:54:30(UTC)
3030guy

Sweden   
Joined: 08/04/2023(UTC)
Posts: 6
Location: Skåne
I recently purchased a big lot of C rails and among them were a couple of what I think is train detectors.

Someone has drilled out a section between two of the ties and inserted something that looks like a detector (magnetic sensor perhaps). The sensor is then connected to a home made PCB populated with a couple of digital IC's.

Does anyone have more information as to what it is and how to connect it to something ?

Below are couple of pictures of the units.
UserPostedImage
UserPostedImage
Offline mario54i  
#2 Posted : 10 April 2023 13:02:14(UTC)
mario54i

Italy   
Joined: 28/03/2007(UTC)
Posts: 283
Location: Torino,
I would say there is a glass tube in the slot, likely a reed relay. A closer picture of the other side of both rail and pcb could help
Offline hxmiesa  
#3 Posted : 11 April 2023 14:34:41(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 3,519
Location: Spain
Could they be Hall sensors?
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
Offline 3030guy  
#4 Posted : 11 April 2023 19:00:36(UTC)
3030guy

Sweden   
Joined: 08/04/2023(UTC)
Posts: 6
Location: Skåne
Mystery solved, kinda.

The sensor is a photo resistor connected to what looks to be a serial shift register. From what I can see it most likely has a master unit (that I do not have) that sits in the start of a number of these units connected in a chain using 10 pole flat cables. Each connector has 4 signals in total: 1-power, 2-clock, 3-data, 4-Ground, and one of the connectors is an input and the other is an output that feeds the next unit in the chain.

So, when the train runs over the sensor it signals this in a bit in the shift register that the master can read out. The board I have played around with seem to work and I can see the sensor data in the generated bit stream.

Date codes on the chips indicates that it was assembled sometime 1998. It does require that you have a significant amount of light right above the sensor so night sceneries are not possible here.

I will not use these at all so if anyone wants them I can send them if you pay shipping.
Offline kiwiAlan  
#5 Posted : 11 April 2023 21:42:42(UTC)
kiwiAlan

United Kingdom   
Joined: 23/07/2014(UTC)
Posts: 8,082
Location: ENGLAND, Didcot
Originally Posted by: 3030guy Go to Quoted Post
Mystery solved, kinda.

The sensor is a photo resistor connected to what looks to be a serial shift register. From what I can see it most likely has a master unit (that I do not have) that sits in the start of a number of these units connected in a chain using 10 pole flat cables. Each connector has 4 signals in total: 1-power, 2-clock, 3-data, 4-Ground, and one of the connectors is an input and the other is an output that feeds the next unit in the chain.

So, when the train runs over the sensor it signals this in a bit in the shift register that the master can read out. The board I have played around with seem to work and I can see the sensor data in the generated bit stream.

Date codes on the chips indicates that it was assembled sometime 1998. It does require that you have a significant amount of light right above the sensor so night sceneries are not possible here.

I will not use these at all so if anyone wants them I can send them if you pay shipping.


I would expect to find the electronics emulates an s88 sensor, and would probably quite happily work in an s88 string.

Offline BenP  
#6 Posted : 12 April 2023 00:15:42(UTC)
BenP

United States   
Joined: 04/02/2021(UTC)
Posts: 344
Location: Michigan, Ann Arbor
That's pretty fancy electronics for location sensing. Ground sensing or reed switch seem a lot simpler solution (and cheaper).
Ben
Digital M (+ some K) track layout with mostly vintage rolling stock and accessories, and small Z scale layout.
https://youtube.com/play...0kgVYbh0CeDTF-bYXoD_2-V9
Offline 3030guy  
#7 Posted : 13 April 2023 14:41:05(UTC)
3030guy

Sweden   
Joined: 08/04/2023(UTC)
Posts: 6
Location: Skåne
I did a little digging into the S88 stuff but these boards do not comply with this standard. There is for one no PS (load) signal on the connectors. From what I can determine the master unit resets the string of boards by holding the clock signal low for a fixed period of time. When the clock starts each board generates a load signal to the shift register that loads the sensor state but also a few bits from a ripple counter. Not sure what this is for.

However, i have gotten really curious right now so I will connect two of these boards to an arduino and see what I get from it.
thanks 2 users liked this useful post by 3030guy
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