Model rail block detector to drive relay

[Derekm]

Hi I am a railway modeller looking for some help I work with 12v dc
I have a 12 v pcb which has a signal output to drive a open collector input which I don’t really understand

what I want to do is drive a timer relay with this pcb is it possible ?

 

[rjenkinsgb]

An "open collector" output is just a transistor without any already-connected load; in effect, it works like a switch to the 0V connection (or power -).

The timer input would have to be compatible with 12V, and you connect that input between the open collector output and +12V.

 

[Derekm]

The timer relay I have has a low trigger 0 to .1 volt input and high trigger input.

 

[JimB]

It would be helpful if you could give a link to a datasheet for the timer relay, and the device with the "open collector output".

JimB

 

[eTech]

The timer relay I have has a low trigger 0 to .1 volt input and high trigger input.

You can connect the open collector output to a relay coil, then use a NO contact of the relay ( +V to com, NO to timer) to trigger your timer.
or
you can use a transistor to invert the output signal to drive the timer input.

But...we really need to see the block occupancy detector output circuit and Timer info to be sure.
Can you post part numbers?

 

[Derekm]

Hi there is not a lot of info on block detector I asked the question whether it gave a signal and was given the information as I have stated

Block detector – MegaPoints Controllers

And the timer is
https://www.katranji.com/tocimages/files/438402-214756.pdf

 

[rjenkinsgb]

The block detector output is via an opto-isolator.

That would probably connect directly in place of the switch/button shown in the timer diagram?

 

[eTech]

Hi there is not a lot of info on block detector I asked the question whether it gave a signal and was given the information as I have stated

Block detector – MegaPoints Controllers

And the timer is
https://www.katranji.com/tocimages/files/438402-214756.pdf

Hi
Can you post a photo of the back side of the Block detector module please?

 

[eTech]

I think it should be wired this way (see below).
The Block detector output signal is normally held high(12v) via R1. When the DCC input becomes active, the Block Detector output signal will change to low(0v) and trigger the Timer Module. However, this assumes the Block Detector output is normally OFF (high).

If the Block Detector output is normally ON (low), then the wire to the Timer needs to be moved to the HL_TRIG input, so that when the output turns OFF (high), it will trigger the timer.

Whether the Block Detector output is normally ON or OFF depends on the DCC commands.

 

[Derekm]

 

[augustinetez]

Whether the Block Detector output is normally ON or OFF depends on the DCC commands.

The block detector is current driven (it is wired in series with the DCC feed to the rack), so it only activates the LED in the opto when there is something (like a locomotive) drawing current in that section of the track.

Following schematic is almost the same as the board pictured above.

 

[eTech]

View attachment 134051View attachment 134052

I was hoping to trace out the PCB traces to create an accurate schematic, but the posted photos don't show enough detail.

 

[rjenkinsgb]

Following schematic is almost the same as the board pictured above.

Ye. As far as the bridge, resistor & optocoupler part, that's the exact setup I got from the board photo in post #6.

 

[Derekm]

Just to clarify as finding it a little difficult to follow if it will work with timer relay and how to connect. Thanks a lot guys

 

[eTech]

Ye. As far as the bridge, resistor & optocoupler part, that's the exact setup I got from the board photo in post #6.

There is a +/-15vdc bipolar signal being received at the input (the power pack signal).
So is the bridge doing nothing?
I think the resistor is 330 ohm.

 

[eTech]

Just to clarify as finding it a little difficult to follow if it will work with timer relay and how to connect. Thanks a lot guys

Can you post a clearer photo of the back of the Detector PCB so we can see the traces please?

 

[eTech]

The block detector is current driven (it is wired in series with the DCC feed to the rack), so it only activates the LED in the opto when there is something (like a locomotive) drawing current in that section of the track.

Following schematic is almost the same as the board pictured above.
View attachment 134054

That's almost the circuit I traced out.
What is the purpose of the diode bridge?

 

[rjenkinsgb]

The bridge just provides a two-diode voltage drop regardless of polarity. That sets the voltage fed to the opto.

 

[Derekm]

More pics

 

[eTech]

More pics
View attachment 134057View attachment 134058View attachment 134057View attachment 134058

Thanks....that helped.