Block Occupancy Detector for Model Railraod

Thread Starter

sornjs

Joined Dec 29, 2017
29
I found the original circuit in a Model Railroad magazine and can not relocate it. I do recall that the original design used 1 transistor and a couple of parts including the led that would light when the "Block" (stretch of track) was occupied by at least one car. Each car to be detected needed to have some resistance to current. At the time I discovered that the circuit needed the opposite type of transistor than the author used (PNP instead of NPN or the opposite).
This drawing shows, in brief, how a model railroad is wired for Block Occupancy Detection.
Track Wiring for Block Detection.png
Track Wiring BOD Circuit.png This may be the Block Occupancy Near as I can recall. Found on a MRR source.

If this circuit is near correct I believe R2 will just connect to the single "Block" feed where each "Ckt" is shown.
The above is a starting place for the circuit I need. I do not know if any of the components are correct or if the circuit is anywhere near accurate.
Thanks.
 

eetech00

Joined Jun 8, 2013
2,644
I found the original circuit in a Model Railroad magazine and can not relocate it. I do recall that the original design used 1 transistor and a couple of parts including the led that would light when the "Block" (stretch of track) was occupied by at least one car. Each car to be detected needed to have some resistance to current. At the time I discovered that the circuit needed the opposite type of transistor than the author used (PNP instead of NPN or the opposite).
This drawing shows, in brief, how a model railroad is wired for Block Occupancy Detection.
View attachment 180521
View attachment 180523 This may be the Block Occupancy Near as I can recall. Found on a MRR source.

If this circuit is near correct I believe R2 will just connect to the single "Block" feed where each "Ckt" is shown.
The above is a starting place for the circuit I need. I do not know if any of the components are correct or if the circuit is anywhere near accurate.
Thanks.
Hi

It looks like that circuit will work if you connect “track common” to +5v and each track ckt1, for example, to the base resistor of the LED circuit. When the train wheels “shunt” the track, 5v will connect to the base resistor, lighting the LED. You’ll need a ckt for each “ckt” track section.

Add a 10k resistor from the transistor base to GND.

eT
 

Thread Starter

sornjs

Joined Dec 29, 2017
29
Are you using DC to power the trains or DCC to control them?
Using dcc to power track.
Back in the day the club used Dynatrol and when they replaced it with Digitrax it still worked.
Club moved after I quit. Wife and 2 boys, club scots and boy scouts took up most of my time.
 
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