Or to put it another way; more voltage results in less action.
My buddy wanted to install a Lionel signal bridge with the lamps being driven by the DZ switch motor. I looked at the schematics on DZ's website and thought simple enough. We had a DZ-1008 relay to use. I did a bench test with a spare switch, the signal bridge and the DZ-1008, using my bench transformer.
Some days later I wired everything up to the existing switch on his layout. The relay didn't operate. I suspected that since there are several neutral busses on the layout, when I asked for a neutral connection for the relay he gave me one that was from a different transformer than the hot side and the neutrals weren't bridged. I simulated this on the bench and thought I had found the problem because I duplicated the symptom. This was not the solution.
While another buddy and I were trying to get a reading with the VOM, he was adjusting the voltage and I heard the relay click and the light on the signal bridge went on. We fine tuned it to 14 Volts on the ZW with a reading at the switch of 11.72 Volts. At this setting the lamps on the signal bridge followed the switch without a hitch.
I had called Dennis at Z-stuff in the interim. When he called back the next day I explained the whole scenario. Dennis offered that the switch diodes sometimes leak. At a lower voltage they don't cause a problem; however a higher voltage could cause enough leakage to mess with the relay circuit.
Lesson learned.
