Ok Alan, I've gotta ask... I know you don't use sound or keep alives and that ringing is different to too much inrush current but you say
Place a high wattage resistor across the relay input/output and viola, startup surge problems solved.
so what does the board you linked to do over the simple Big Honkin' Resistors that you use by themselves? and lack of locomotives with capacitor in them to charge aside, if you'd been wondering why manufacturers don't include it why didn't you build in a soft start for the power on the LK&O? Just curious.
- Tim
Two different problems, two different solutions.
My big honkin' resistors reduce
over-voltage spiking (ringing) on startup. The eBay board + relay resistor reduces
inrush current on startup. My big honkin' resistors are in
parallel with the load, the eBay board resistor is in
series with the load.
If you recall from our private messages, I was without oscilloscope when installing the LKO power system (Note to all: don't spill coffee on an operating oscilloscope). I was forced to rely on a SPICE simulation that showed considerable voltage ringing. Since that time my wonderful wife gave me a new oscilloscope as a Christmas present. A nice one to boot. Hands off, she's all mine.
With the ability to actually measure the system I have discovered the voltage ringing is not nearly as bad as the simulation indicated it would be. It's there but much, much less than predicted. Probably due to the various loads installed since (30 occupancy detectors, 52 Tortoise machines, hundreds of LEDs, etc.). These loads were not included in the simulation. I am now considering removing the big honkin' resistors. With concerns of voltage ringing abated, the resistors are really nothing more than a parasitic load on the system. It's a shame too, because they look so cool.