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I want to install a delay relay in the trigger wire to a couple of MTH road crossing gates. They are actuated by a pair of DZ-1011 trackside sensors and DZ-1050 block signals all feeding a DZ-1008 relay which powers the gates. This all works fine but every time I power up the layout the DZ's all wake up in "triggered" mode, and the crossing gates promptly cycle down and then immediately back up again. This is annoying plus needless wear and tear on the crossing gates, which as we know are a fragile beast at best. I have never used a time delay relay, but I was thinking of something like this guy set for about a 30 second delay:

Time delay relay

This looks like it would do the job, but is there something better suited to the task?

Any thoughts?

Rod

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  • Time delay relay
Last edited by Rod Stewart
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@Rod Stewart  Like Arthur suggested, a manual switch may also work, but I presume you would prefer something that solves this issue automatically upon powering up your layout.

I found DZ-1011 instructions on the Z-Stuff website showing wiring diagrams for connecting the DZ-1011 and DZ-1008 to an MTH Crossing Gate [EDIT which have an error, see Rod's later attachment for corrections]:



Here is also a link to instructions for the DZ-1050 Trackside signal:



Interconnecting all of these devices may possibly be achieved in more than one way, and knowing how you did is uncertain.

Would you consider posting a diagram showing your existing connections between the DZ-1011 sensors,  DZ-1050 signals,  DZ-1008 relay, the MTH crossing gates, and their power supply(ies)?  I think this may help us discover additional answers to your question.

Last edited by SteveH

Put a 19 cent switch in series with the gate power lead. Leave it off until the other stuff settles down and gets done cycling. Then turn it on.

@SteveH posted:

... Like Arthur suggested, a manual switch may also work, but I presume you would prefer something that solves this issue automatically upon powering up your layout.

Can't beat the simplicity of a 19 cent switch.  But in addition to turning it on, one must remember to turn it OFF at the end of the day.  I think the automatic part is of value and worth busting the 19-cent budget!

Turning attention to the time delay relay approach.  As you are proposing a 12V DC module I assume you have 12V DC available and that this 12V DC powers-up at the same time as the crossing gates. Generically what you are looking for is a so-called "Delay OFF" relay module.  In other words when you apply 12V DC (i.e., a trigger) to the module, it immediately turns ON the relay, waits a settable delay, then turns OFF.  Hence the sequence is RELAY-ON, DELAY, RELAY-OFF.  You'd use the NC (normally closed) contact of the SPDT relay.  When the relay is ON, it blocks the gate trigger from reaching the crossing gates during the startup delay interval.

OK, why do it this way rather than a "Delay ON" timer module that waits some delay and then turns the relay ON?  Well, that would mean the relay is powered ON for the entire duration of your operating session (except the first few seconds of the delay).  And while you may have gobs of 12V DC power available, it just exhibits poor form to burn relay power for hours upon hours when the relay already got its 15 seconds of fame - in my opinion.  But to each his own and a "Delay ON" relay module would also work using the NO relay contact which would block the gate trigger from reaching the crossing gates during the startup delay interval.

I'm not familiar with the particular relay module, and perhaps it would work.  Sometimes it's hard to decipher how a timer relay module works as eBay/Amazon instructions can be poor English translations...and other times simply incorrect.

I've used the following time delay relay module in many applications.  It's widely available (eBay, Amazon, aliexpress, etc.) and sometimes goes by the model number "JZ-801".  It should be available for less than $5.  It may be over-kill, and you do have to fuss with the buttons to "program" the timer mode and the delay interval...but I know it has the "Delay OFF" mode and you could set the delay with digital precision not that you need it. There are cheaper relay modules that "only" perform the Delay ON or Delay OFF function.

jz-801

But, it seems to me there was some guy right here on OGR that was messing around with time delays using those generic, $1 per relay, multiple relay modules for Arduinos.  I think he even fabricated some PCBs to add the timing function to the basic relay.

So, for example, marking up the schematic:

power-on delay-off modification

Upon application of power, the above circuit driving a "trigger low" Arduino relay module would turn on the relay for some settable delay time (around 10 seconds) and then turn OFF.  The lower diagram suggests how the circuit could be built using an existing PCB design inserting the components in existing holes.  Yes, it's arguably a kludge, but I figure this is a one-off.

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  • jz-801
  • power-on delay-off modification
Last edited by stan2004

Thanks for the ideas all. Arthur, I would do the switch thing (KISS) except the gates are no where near where I operate from, and getting to the switch would require crawling under the layout and using an access hole. Mostly I would forget to turn the switch on and the gates would never operate I suspect.

I'm not sure it's a simpler solution to the off-the-shelf relay, but could you rig up a circuit that uses a an RC delay to turn on a triac, the triac then controlling power to the DZ-1008?

I think the time delay relay would be way simpler than what you are suggesting, plus I don't have to remember to turn anything on. Thanks though for the idea. My plan is to use the TDR to turn on power to the 1008, or maybe just the blue wire common to the 1008 from the gates.

@SteveH posted:

@Rod Stewart  Like Arthur suggested, a manual switch may also work, but I presume you would prefer something that solves this issue automatically upon powering up your layout.

I found DZ-1011 instructions on the Z-Stuff website showing wiring diagrams for connecting the DZ-1011 and DZ-1008 to an MTH Crossing Gate:

Here is also a link to instructions for the DZ-1050 Trackside signal:

Interconnecting all of these devices may possibly be achieved in more than one way, and knowing how you did is uncertain.

Would you consider posting a diagram showing your existing connections between the DZ-1011 sensors,  DZ-1050 signals,  DZ-1008 relay, the MTH crossing gates, and their power supply(ies)?  I think this may help us discover additional answers to your question.

Thanks Steve. Note though that figure 3 you attached from Z-Stuff is totally wrong. It shows the white output from the 1011 connected to ground of the 1008, and the green 1008 input connected to power. Many years ago I first tried wiring them this way, with no joy at all.

I have my 1011 white's wired to the green 1008 wire thru a 1N4148 diode, which prevents the red led on the 1011's from staying dimly lit when the greens are lit (a quirk of the 1011's I find very annoying). And when one 1011 triggers the other goes red too.

The 1050's also trigger the 1008 through a diode, and they trigger each other and they trigger from the 1011's. It all works well and is the result of several exchanges with Dennis Z. a very helpful guy for sure.

I could scan the circuit diagram but you would laugh out loud at how crude it is. It got started many years ago.

@Rod Stewart posted:
...Thanks Steve. Note though that figure 3 you attached from Z-Stuff is totally wrong. It shows the white output from the 1011 connected to ground of the 1008, and the green 1008 input connected to power. Many years ago I first tried wiring them this way, with no joy at all.

I have my 1011 white's wired to the green 1008 wire thru a 1N4148 diode, which prevents the red led on the 1011's from staying dimly lit when the greens are lit (a quirk of the 1011's I find very annoying). And when one 1011 triggers the other goes red too.

That's good to know.  I wonder why they haven't corrected the instructions on the Z-Stuff website?

@Rod Stewart posted:
I have my 1011 white's wired to the green 1008 wire thru a 1N4148 diode, which prevents the red led on the 1011's from staying dimly lit when the greens are lit (a quirk of the 1011's I find very annoying). And when one 1011 triggers the other goes red too.

The 1050's also trigger the 1008 through a diode, and they trigger each other and they trigger from the 1011's. It all works well and is the result of several exchanges with Dennis Z. a very helpful guy for sure.

I could scan the circuit diagram but you would laugh out loud at how crude it is. It got started many years ago.

Rod, your text description is helpful.  I think a diagram would be even better showing the connections that actually work, per your conversation with Dennis and based on your personal experience.  I promise not to laugh if you do decide to post it. (Especially since my diagrams aren't usually very neat either).  It's the concept that's important, IMO.

Last edited by SteveH

Stan2004; I posted my last post above before reading yours. Good idea the simple delay board concept; (I think I know the guy you are referring to). And i just might have all the parts on hand too! Have to play with your idea a bit. A 10-15 second delay should be ample. I have never timed the present startup cycle, but it can't be more than maybe 5 seconds all told. Have to check.

Rod

@SteveH posted:

That's good to know.  I wonder why they haven't corrected the instructions on the Z-Stuff website?

Rod, your text description is helpful.  I think a diagram would be even better showing the connections that actually work, per your conversation with Dennis and based on your personal experience.  I promise not to laugh if you do decide to post it. (Especially since my diagrams aren't usually very neat either).  It's the concept that's important, IMO.

Actually Steve I likely won't be able to hear the laughter all the way out west here anyway! But here is the circuit regardless.

Once you are finished LYAO, some comments on the drawing: The two 1011's are close to the gates, 2-3 feet either side. The 1050's are several feet farther away, in both directions. So the idea is the 1050's provide advance gate closure and trigger all other signals. The 1011's are probably redundant, but they were there first years ago, so I just left them in place.

The 1050 in the lower right does not have its white connected because it has some internal issue and there is no white output (I bought the 1050's used). Diode D2 isolates the lower left 1050 and enables it to trigger the 1011's and the gates. Diode D1 allows any 1011 to trigger both 1050's to red, but also allows the white from the 1050 to trigger the gates. When the 1050 triggers it also triggers the 1011's to red. Hope that makes sense.

I also attached a pdf of a compatibility matrix I made up for the Z-Stuff items, plus some installation notes I have put together along the way. These were mainly just for my own reference because after you haven't played with these things for a while you have to re-learn everything all over again. But here they are in case they can help anyone out there. I sent these both to Dennis last year, so he knows all about them. I probably have 30 odd Z-stuff sensors running various signals, gates, block signals, semaphores, flashers, you name it on the layout. Last year with covid going on I took the time to upgrade several of the installations and got with better signal operation all around. They work much better now.

Rod

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Rod, thank you for sharing your diagram, chart and notes.  They're all perfectly legible to me   and very helpful.  I think I see where you are considering adding the power-up delay relay.  I like both of Stan's implementation suggestions. If you decide to go with the off-the-shelf delay relay and connect it like Stan suggests, so that the relay is only energized when the layout is first powered-up, I think it would go something like this.  Using your diagram as a reference:

Delay Relay Connections

  • Common input: the combined outputs from the two diodes (sourced from the DZ-1011 and 1050 detectors' trigger output signals; Whites)
  • Normally Closed: Green Input wire to DZ-1008
  • Normally Open: not connected


Is this how you are planning to connect the delay relay?

Actually Steve I was thinking to insert it into the blue wires from the crossing gates (after they join) going to the 1008. Those blue wires feed hot to the relay common, so breaking that should prevent unneeded gate cycling. Or if that doesn't seem to work satisfactorily I would next insert it into the main red power connection that feeds the whole works at this location. That's the 14VAC power on the highly exotic circuit sketch.

And yes I will likely connect it between the NC and COM connections and energize the relay only at startup until it times out. That will be the plan anyway, subject of course to change!

Rod

One concern I have about this is that if the relay does not activate almost instantaneously, there will be a blip of power to the circuit before the NC-C points break; since it's the same power supplying the TDR as for the gate installation. This would not be desirable. If that happens I will change it to NO-C connections and when the relay activates after the timeout it will close the points and power up the signals and gates. This is opposed to Stan's suggested method of hookup, but it's fail-safe open, or unpowered, and might work better.

Rod

Last edited by Rod Stewart

Now that we are back home I finally got with the plan to install a "Delay Off" type relay to try to solve the gate cycling problem originally discussed in the OP above. This is the module I installed:

Type 3 TDR Relay Pic

Most of these time delay modules have to be triggered by some external source to start the delay timing. This was the only one I found that will power up with the relay triggered, then count down the preset time and release the relay. Jumpering the KEY contacts (left end) sets it to power up triggered. I connected the blue power wire from the gates to the relay COM terminal (right end), and the blue power supply common to the DZ-1008 to the NC terminal above. I set the time delay to 15 seconds after timing the complete gate cycle at about 10 seconds.

So the module powers up with the relay triggered and the NC connection open; no power to the gates. then after 15 seconds the relay untriggers, the NC connection is powered and the gates can operate normally. Actually there is a fraction of a second delay in the relay triggering, so the gates move about 1/2" when first powered up. But when the relay untriggers they immediately reset to full up position. It's not as perfect as I would have liked, but it's close. It beats the heck out of the gates completely cycling needlessly down then up every time the layout is powered up.

These modules cost about $5 each on ebay with free shipping. The lower right indicator shows the exact time delay in seconds, or minutes; selectable using the jumper in the lower left corner. The white pot is used to set the delay time exactly where you want it. Easy-peasy. Ranges are 0-99 seconds or 0-99 minutes.

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  • Type 3 TDR Relay Pic
Last edited by Rod Stewart

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