Servo Controlled Crossing Gate and Turnouts

[Greatnorthern]

For sometime now I have been using servo's to control road crossing gate, my train order signal and my turnouts. The problem that I have is that sometimes when I push a button for a turnout the crossing gate activates. Has anyone come across this problem. Help would be appreciated.

 

[GGNInNScale]

I had similar problems- with Arduino control. The issue is the current pulse to the switch coil creates an significant electric field. This can activate other devices if they are in a high impedance state. You are probably seeing a false trigger of the servo drive wire. The fix is to buy some small gauge coax cable, ground the shield at one place (the servo power ground is a good spot), then connect your switch to the center wire of the coax, then to the servo drive wire. This should stop the problem. You can get the coax on the internet cheaply.

 

[Greatnorthern]

Thank you for your suggestion. I changed the 6 turnout servos and the crossing gate servos to coax cable with no success. I then realised it must be the relays I have connected to the servo micro switches to control the various functions. 24 volt relay to the PLC for the automatic signalling, the turnout dwarf signals and the panel LEDs. I disconnected the relays the the problem seems to have gone. I now have hours of rewiring. Regards

 

[GGNInNScale]

Hi I did not know you were using 24V. This will create a much larger upset than I thought. You might try to put a Diode snubber on the coil. Easier than rewiring all over the layout. The diode will sink the back EMF, but stand off the DC bias. Here is a reference:

Safegaurding Circuits: The Essential Guide to Flyback Diodes

Safegaurding Circuits: The Essential Guide to Flyback Diodes

components101.com

There are lots of references. (note the spelling error in the link...)
Hope this helps!

 

[Greatnorthern]

Hi I did not know you were using 24V. This will create a much larger upset than I thought. You might try to put a Diode snubber on the coil. Easier than rewiring all over the layout. The diode will sink the back EMF, but stand off the DC bias. Here is a reference:

Safegaurding Circuits: The Essential Guide to Flyback Diodes

Safegaurding Circuits: The Essential Guide to Flyback Diodes

components101.com

There are lots of references. (note the spelling error in the link...)
Hope this helps!

Thank you for the information. I thought about using fly back diode but have decided to rather rewire. Thanks once again.