MTH 30-11038 Dwarf Signals

Don't supply the MTH signals with more than about 12-14 volts.  I have a bag of the PRR style signals with the same electronics, they're all toast from running on 18 VAC!   It apparently is taking the 555 chip out, haven't gotten around to fixing any of them yet.

So they are AC Voltage. I was thinking of using the DC side of the Tyco transformers and setting the voltage to whatever it was suppose to be. So I guess it has to be AC that cancels setting the DC Voltage to 14 volts and using that. Thanks for he answer I appreciate it.

CurtisH posted:

So they are AC Voltage.

Not sure that's what GRJ said.

I read his comment as too high a voltage may not play well with certain MTH signals...nothing about relative suitability of AC vs. DC.

Why not just hook it up to 14V DC as you were planning and see if it works.

The signals run on AC, but if you run them for any length of time from 18VAC, they seem to die. We had seven or eight of them on our modular club layout, all but one or two are in a bag on my workbench with busted electronics.

Of course, MTH says between 10 and 18 volts, but don't you believe them!   These were all running from a PH180 brick, and I know they're not getting more than 18 VAC.

Are you saying they don't run on DC? 

Why does a red-green dwarf signal have "electronics" in it (555 chip)?

MTH 30-11038 Dwarf signals User Instructions, seems there's a control box for it.

gunrunnerjohn posted:

The signals run on AC, but if you run them for any length of time from 18VAC, they seem to die. We had seven or eight of them on our modular club layout, all but one or two are in a bag on my workbench with busted electronics.

Of course, MTH says between 10 and 18 volts, but don't you believe them!   These were all running from a PH180 brick, and I know they're not getting more than 18 VAC.

And don't forget there is a filter cap which ups the DC voltage, unless there is a heat producing ballast resistor and zener to knock voltage down to what the 555 likes.