Hobbyist electronics/wiring question

[Possessed Freak]

Notes:
1) Everything is running at 5v
2) This needs to be done on the cheap, there will be 100+ of these circuits on one project and I am trying to keep the price per part way low.
3) It is Arduino based, and I am already using shift registers to control a lot more outputs then I have access to.

Problem: Imagine multiple electric trains running along on their own circuits. They run over a physical switch that opens the circuit killing their motors. Later, I want to remotely close the circuit (all 100 of them) at the same time to allow the trains to run again. Now the fun part, some of these circuits will already be closed (IE some trains did not run during the last iteration).

Now the switch particulars, I would like it to be lever actuated, and on the pressing of the lever it opens the circuit. It can NOT be a momentary as the 5v power needs to be severed for a length of time to different circuits until an all go signal is sent.

My brain is trying to wrap around this and it basically seems to be a half relay half switch idea.

 

[jaedaliu]

Later, I want to remotely close the circuit (all 100 of them) at the same time to allow the trains to run again. Now the fun part, some of these circuits will already be closed (IE some trains did not run during the last iteration).

Tell me how you want to tell the trains to run again. You press the switch again? (Maybe removing the train that was sitting on top of the switch when it ran over it and shut off?) Or software command?

What happens to the trains whose circuits that are already closed? Were they running while the previous bank of trains were shut off by the switch? Do they stop running when you start running the others? or do they just keep running? Or were they also stopped with their circuit closed?

Is this an open area with cables running to each train? or are you planning on communicating/powering via traces on the track/surface? or are you using self contained trains with batteries and wireless?

Is there a track? Are the only signals you need to send Power off/Power on? or do you need a go/stop signal too?

 

[Possessed Freak]

Okay, it is not actually trains as the project but it was the simplest explanation of what happens. Many somethings will physically encounter a switch on an isolated track that will open the connection to their motor, stopping them. These many somethings are given power through individual relays whose coils are controlled by shift registers so that I can enable specific ones to run.

So I want:
1) To send power to specific coils to enable motors so specific units run (working)
2) A physical switch that opens the circuit killing the power at specific points, these points are fixed for each unit. (easy)
3) After a time, send a command to remotely enable the trains to run again (basically close the switch remotely). (?)

I don't think I can use a latching relay as some of the units will not encounter the switch so the relay may or may not be in a specific state when I send power to specific units again.

 

[festa_freak]

I've never used arduino but other microcontrollers. Could you have the switch wired to an input on the arduino and then trigger in software the outputs to the trains? Then after a software delay re-initialize the outputs?

 

[skimple]

If your talking motion, use an optical sensor. Trigger pulse creates the cutoff event. Subsequent state/pulses ignored until circuit is re-energized.

 

[Possessed Freak]

Thanks for the replies so far.

I am trying to do the cutoff/restart at a electro-mechanical level so I don't have to try to read 100 sensors simultaneously (while still in my main program of moving the units).

 

[OCGuy]

OP is this something Homeland Security needs to worry about?

 

[skimple]

Apparently you are operating asynchronously. If you have to trigger off of one of many possible events (any one of the "trains" could reach the switch before the other) the only way to avoid multiple sensors would be to hook them up in parallel (sort of like a pull-down). Only one input to monitor, but can be triggered by many possible switches.

 

[skimple]

You might consider looking at "safety interlock" schemes for wiring ideas.

 

[jaedaliu]

You might consider looking at "safety interlock" schemes for wiring ideas.

yeah, this type of thing. the switch and the input working together like a lightbulb wired to 2 light switches. Flip either one and it switches state.

I would imagine a solid state relay wired to a xor switch wired to your arduino output signal and the switch.

 

[Scarpozzi]

1. Assign each circuit with its own variable name.

2. Create a loop that sets them with the state they need to be in based on
whatever criteria you wish...(like a foreach loop)

3. After that loop completes, have an execution foreach loop that sets the states.

Splitting it up into Define, Set, Execute will help keep the processing side of it isolated from what you're physically trying to accomplish and keep the timing of them actually turning on closer together. Arduinos work in execution loops anyhow, so it should be pretyt basic.

 

[Possessed Freak]

OP is this something Homeland Security needs to worry about?

Worry about, no. Think it is cool (assuming they are into train boardgames), yes.

Thanks guys for the ideas. I will (obviously) have to research this a lot more.

 

[DesiPower]

love them toy trains, ttiwwp