Walt, I presume your accessories consist of inductive load devices (relays, solenoids, AC motors) that can be sources for the EMF voltage spikes.
I guess my rotating beacon and PW swinging crossing gate are probably the only things that qualified then. I have stuff like the MTH operating station, gantry crane, whistle shed... but I don't think those have the parts in them that you mention. AGAIN, sorry for not understanding electrical things very well !!
- walt
John Meyncke posted:I got my order from Digikey today. Flawless and perfect and an American company! Thanks to Gunrunner John for the suggestion. I now have a reliable source for electronic products. I highly recommend them.
Now on to the install!
Ditto. Have been purchasing from them for several months now after recommendations here on the forum. Excellent service and super-fast shipping.
And don't forget to add an inexpensive 10 amp circuit breaker also.------------TVS for the train's and a 10 amp circuit breaker for the transformer.I think this is correct.
A spike, if it's strong enough, can easily jump a switch connection. Lightning can come right through the wall. Back in the mid 60's, when I was a kid, lighting hit a water tower a half mile away, bounced off that, hit our outdoor tv antenna, came down the antenna wire and fried out the tv antenna. Never underestimate the power of any electrical source.
Most bets are off when the spikes are millions of volts! 
Great read. Question, what about DC applications?
Background:
I run both ac and dc on an old school conventional two rail pike. Each power source is attached to one end of a d.p.d.t. toggle. The center toggle pair goes to the posts on an MTH terminal board which distribute either ac or dc to blocks around the layout.
There are four major branch lines totally separated electrically. So there are four pairs of ac and dc power sources feeding into four MHT power distribution terminal boards.
So I can run conventional dc on one branch line while a PS-3 is on another branchline.
All branch lines converge to a interchange yard.
Application questions:
I am guessing a TVS connects each end pair of each d.p.d.t. terminals with respective ac or dc TVS devices.
What TVS for dc?
Is there a multi use ac&dc TVS to use for the MTH terminal board posts?
If attaching both ac and dc TVS do they play nice with one another?
In addition to the main panel there are also 7 other towns or yards around the 2 rail layout each with fully selectable ac or dc option.
Main panel:
Tape on power pack controls same color tape on schematic. Other packs adjacent,
White, red left side & black, yellow right side tape above toggles above the Z-1000s flip ac and dc.
Typical of town power:
There are also some individual 3 rail ac only ZW & Z-1000 routes running at different levels which I will treat as recommended earlier.
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Tom, one size fits all for the TVS, the same one will work for AC or DC, I use this one: 1500W 33.3V TVS at Digikey. There's no reason you can run AC on one line and DC on another line, just as long as they don't actually end up being connected together. You can also run PS/3 stuff on DC, and if it's all PS/3, it doesn't care about polarity. PS/2 runs on DC, but PS/2 does get picky about polarity.
gunrunnerjohn posted:I use this one: 1500W 33.3V TVS at Digikey.
Did not know you switched from the 36V model. I thought Dale's recommendation was the 33V version if your max input was 18VAC, 36V for transformers like the Z-4000.
How does one control a -2 entering / exiting a TT?
Three of my TTs have a 180 degree split rim rail.
Problem some of my TTs are Millhouse which power the bridge through the center shaft and the solid 360 degree ring rail. Great for 3 rail but not for two rail. Maybe I should move this question to another thread??
TVS for the dedicated TT powerpack?
So, to confirm TVS across the switchable + & - output of dc packs?
No selectable direction change of + & - to - & + affecting TVS operation?
CAPPilot posted:gunrunnerjohn posted:I use this one: 1500W 33.3V TVS at Digikey.
Did not know you switched from the 36V model. I thought Dale's recommendation was the 33V version if your max input was 18VAC, 36V for transformers like the Z-4000.
The 3V isn't all that significant, and one size fits all.
Tom Tee posted:So, to confirm TVS across the switchable + & - output of dc packs?
No selectable direction change of + & - to - & + affecting TVS operation?
Polarity doesn't matter, so just slap them across the power. You can also put them at the track connection, perhaps a bit better location.
