TIU passive mode watchdog indiviual channel control question.

If you're using the TIU in passive mode, the fact that there is no power on the input or output of the channel will "reset" the channel, and when power is applied, the WD will be generated.  I think Barry was talking about the TIU channel already having power and you simply switching power to the siding on to the already powered loop.

John,

I think Barry was talking about the TIU channel already having power and you simply switching power to the siding on to the already powered loop.

That;'s correct. Thanks for the "assist"  

Does the 0 to some voltage to issue the WD have to be applied to the inputs and will not work on the outputs?

Applying it to the outputs is fine, works for all four channels.

With the TIU on can i use a spst switch in line with one of the feeders from the Z1000 (basically applying track power) to issue the WD?

willygee posted:

With the TIU on can i use a spst switch in line with one of the feeders from the Z1000 (basically applying track power) to issue the WD?

I don't see why you can't... The watch dog goes out each time the voltage on that channel  is raised above 0. So turn on the  channels  input feeder using a spst toggle and out goes the watch dog.  

It works just fine.

Will the track feed to fixed 1 out (which powers the TIU if i'm not mistaken) interfere with the aux in z750 which also powers the TIU?

With aux power plugged in, the Fixed #1 does not attempt to power the internal TIU circuitry.

Thank you gentlemen..just for clarification what is the term used when not using "passive" mode? Active, normal

Normal.

gunrunnerjohn posted:

Applying it to the outputs is fine, works for all four channels.

gunrunnerjohn, and all other electronic gurus here...

... in case this could be of interest to you ...

On the passive WD subject, I have started to develop a passive solution concept a while ago to take advantage of any passive WD sources for a period of 10 seconds.  It is an "On-Demand WD trigger". 

The first idea was to be able to use ONE single PBW (perpetual barking watchdog) to serve multiple tracks, as required. (ref: https://ogrforum.com/...89#70974704667412389 ). 

While doing the prototype, I then realized that this concept could be used with any passive WD source (ex: an unused TIU output !)

The passive (i.e, it does not need any separate power) circuit detects the transitions from 0Vac to 18Vac on a track, flips a relay for 10 seconds to power and connect momentarily the track to any passive WD sources, which in return immediately provide the WD signal to the newly powered track.  The process lasts 10 seconds, stops, and it is ready to be triggered again.

I unfortunately do not find enough time these days to fully complete this concept, but the prototypes I made proved it to be working/promising.  It is obviously an unfinished project at this moment, but a good starting point, in my opinion.

Attached is the relevant information on where I brought that project until now.  If someone wants to pursue the concept, please share your progress and successes !

Note 1 : I asked help for the circuit design on the electronics stackexchange.  The details are available at:  https://electronics.stackexcha...endent-power-sources

Note 2: The attached video shows the circuit connected to a PBW (perpetual barking watchdog).

Enjoy !

Connecting two TIU channels together is not a good idea, so using a spare TIU channel may not be the best solution.  I had come up with a simple solution for our modular club yards, I just wanted to signal on the currently powered track.  Since we have a rotary switch to power the tracks, only one is powered at a time.

gunrunnerjohn posted:

Connecting two TIU channels together is not a good idea, so using a spare TIU channel may not be the best solution...

 

I fully agree that this does not seems to be the right thing to do with a TIU, but at the same time, when you think about it, that is exactly what happens each time locomotives or rolling stocks (with two pick-up rollers) pass over two isolated blocks powered by two separate TIU channels.  These locomotives or rolling stocks could also be stopped right there over an isolator, making a permanent connection between two TIU channels. 

I might be wrong, but as far as I know, there is no rule about where to stop a locomotive on a layout. 

My point here is not to start a debate.  It is just an observation that a connection between two TIU outputs  occurs most probably every 10 seconds on a busy layout, in passive mode or normal mode.

The prototype "On-Demand WD trigger" circuit proposed does that passive connection for 10 seconds, just the time to get the WD sent properly. 

That being said, and while I  did not have any problems during all test performed with any passive source of WD,  I would strongly recommend to use a standard DCS Remote Commander (http://mthtrains.com/50-1033) or a PBW (perpetual barking watchdog) in a passive mode as a WD source.  Nothing will get damaged for sure !

The "passive mode" has obviously some counter-intuitive advantages and mysteries ! 

Daniel,

My point here is not to start a debate.

That's good, because there is no debate to be had

Intentionally bridging two TIU channels is simply a bad idea for a number of reasons. If they belong to 2 different TIUs, it's a worse idea.

Barry Broskowitz posted:

Daniel,

My point here is not to start a debate.

That's good, because there is no debate to be had

Intentionally bridging two TIU channels is simply a bad idea for a number of reasons. If they belong to 2 different TIUs, it's a worse idea.

Agreed Barry, but...  ...oupsss,... that's right,  "no debate",  that's what I wrote  ;-)  !