OK so there are several schematics that I reviewed from DZ and others, but each one did NOT completely extinguish the opposing LEDs. Even using the DZ-2502 does not completely turn off the opposing LED; so if the switch is set to Green you can see some leakage in the RED led. 

I want none because I will be wiring LEDs directly to a control panel and one one LED may be lit for each machine at a time.

So what I required was a sort of break-out circuit board for at least 25 switch machines that would wire to 25 DZ-2500s on the layout and from that circuit board to the panel where I needed to wire one momentary switch and two LEDS (one green and one red) for each of the 25 switches.

DZ had a circuit diagram and ROYZ at ROYZTrains had a circuit board;each one does not completely shut down the opposing LED. Meaning if the switch machine is  set to one position and say the Green LED is lit then for these circuits the Red LED is not bright but still lit. This would be very confusing on a control panel for 25 switches with 50 LEDs some which are partially lit.

So during this Turkey period my son, a part-time electrical engineer and his good friend a full time electrical engineer, created a circuit i can use to create a breakout board for at least 25 DZ-2500 switch machines that will replace the DZ-2502 controllers. 

I have a working (animated) schematic that in the next month or some will become a circuit board that some Chinese firm will build for me. I will likely make a few of these break-out boards since I have several control panels of different parts of my layout that I laser cut.



Original Post

Hey Alan....yep...I am disappointed with my DZ-2500's and the 2502 controllers. I have 23 of them. I just spent over two weeks making my control panel drilling all the holes for the 2502's. After hooking up all the wires, I notice the same issue. I even have a few 2502's that both the red and green are on "full power" at the same time. 

I have some problems with the 2500's. A few are finicky and do not cycle all the time. 

I have to stay my course for now...I am not about to make another panel or replace all my motors.

My old layout I had 40 DZ1000's and never had any issues. But I had to use the DZ1008 relay with each one plus they were 3 times bigger than the 2500's. 

Good luck with your project. I will be watching if you provide updates later.



"If two rails are good, than three rails has got to be better."


"Give a person a toy train and watch them play for a day. Teach a person to fill their basement with trains and give them a lifetime hobby."

Sounds interesting, I know this has come up here before so it seems to be a problem for others as well. Would you consider posting the schematic of the circuit? We just started working on a list of projects that have been designed here on the forum and this would be a very good one to add to the list. We are trying to organize them somewhat so they can all be easily accessed from one thread.

Anyway, I was just doing some comparisons of different PCB makers and posted this info about a few of then and their pricing yesterday. Some of them also offer a few free assemblies as well, but I didn't check into that as I have never tried it. I thought this might be of some interest to you for ordering your control panel boards.

If you are interested, here's a link to the thread where we are working on the projects list: Creating a List of Electronics Projects developed on the OGR Forum

Yes I will. The circuit uses two MOSFETs (whatever that is ) to switch power to the LEDs.

DZ-2502 controller circuit

 press the H (high) to change to L (low) that simulates what the DZ-2500C sends back to the controller to trigger the LEDs; Both LEDS shown are RED for on. Two are shown so that one remains on the breakout board for testing. Moving your mouse around will show the current and voltage at the various components. The momentary switch is not shown but that  just grounds the circuit to the White wire on the DZ-2500C

My laser cut control panels as well. Because it's cut by a laser cutter and not an Xacto knife I can make the track lines as inlays in another color of Plexiglas and perfectly inlay the track lines into the panel.

All holes for LEDs and momentary switches are not drilled but again perfectly laser cut too.


Last edited by AlanRail

I build a control panel at our model rr club years ago for DZ-2500's and DZ-1000's. Used push buttons and 3 mm led's. If I recall correctly I had led's that would not go completely out. Flipping the polarity to the led fixed that. Try that do the led that won't go out or both. I used separate led's , not bi-color,  green for through route and red for diverging.


Also had this problem at the switch machine. They were keyed to install only one way. Reamed the hole out so I could reverse the Led. Problem solved.


Thanks for the link, that is pretty cool. I gotta learn how to create those animated circuits! I have seen a couple of websites that do that, others have done things with them, but haven't gotten it figured out.  

Please keep us posted on your progress with the PCBs and how it all works out. I think this is good info for the project list.

One thing is probably the LEDs are not very good quality and may have different forward voltages. Ditto el cheapo MOSFETs if they are "leaky" source to drain.

Basically, the first MOSFET when conducting (LEDs on) has to pull the second MOSFET gate almost to ground to insure reaching cutoff below the two LEDS forward drop of ~4V.  If the first MOSFET gate is not near 0V cutoff, then it may be operating along its curve resulting in its LEDs not fully on lighted.  When the first MOSFET gate is 0V, the second  MOSFET gate has to be high enough to insure the MOSFET reaches saturation completely lighting the LEDs.  If the first MOSFET is not completely on saturated, then the second MOSFET gate may not be pulled to 0V and lettig the LEDs light dimly.  The 10K resistors might need adjusting to get the gates into their cutoff and saturated regions.

Also wondered about the 1K current limit resistors.  If we assume V+ is 5V and the two LEDs drop 4V and run at 10mA, then resistor could be dropped to 100 ohms which would leave headroom in case V+ varies.

Feel free to correct my assumptions.

Last edited by rrman

Interesting comments.  I have the Royz Trains 2502 replacement control at several locations on my control panel.  The two LEDs are only one together when the pushbutton is depressed.  After releasing they indicate the position of the Z-2500.  The 2502 steals power from the 2500 thus loading it down.  The Royz Trains replacement board does not.  What it does do is use around 50uA from the 2500 digital signal line.  I can operate multiple 2500 simultaneously! 

The only downside is if the 2500 is not properly installed and a "request" to throw the switch does not fully engaged/throw the points...the control panel just shows where it was positively placed last.  At least I know to go check the physical switch to see what wrong!

Moon Doggy

DZ-1000's do not need the DZ-1008 to wire with momentary toggle and led's.  http://www.z-stuff.net/app17.html  This is the instruction page.  You will need to install a diode to direct which way the signal runs.  Use aux power of 14V.  They will not work on 10VAC.  Do not use track power to activate the switches.

Could not find momentary toggle switch  w/led's for the DZ-2500.  You may want to contact Dennis, he may be able to help.


Last edited by bruce benzie

Bruce, you don't need a toggle switch with the DZ-2500.  Just a momentary push button properly connected.  However, with the DZ-2502 the LEDs suck power from the 2500 which can degrade the performance!  So you need to use very low current draw LEDs if you want a separate circuit, or use the alternate unit by Royz Trains which includes its own supply for LEDs.

Moon Doggy

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