Our model RR club uses a 25vac transformer to operate a signal system.

My question is - Is there a way to reduce the 25vac down to 18vac? A few people said to try a rotary light dimmer. It didn't work. If it was a "DC" circuit, I could use a regulator. I have no clue since it's "AC".
Worst case would be to use a seperate 18vac transformer. Would rather not.

-- Hrudya1

 

Use a seperate transformer - mains to 18Vac would be by FAR the easiest method. You could use a 25V to 18V transformer, but you would probably have to wind it yourself?.

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No need to state AC transformer, as all transformers pass only AC voltage. How much current are you going to need at 18VAC, and is the current load Constant or variable? Given not too much current and a stead load, a simple resistor can drop the 7 volts you need. Depending on the current draw, if too high, the resistor would have have a higher wattage rating and would dissipate a lot of heat. A variac is a somewhat impractical solution as it would be simpler to just buy a correct rated transformer to begin with. Another possible solution that can be a little awkward is to remove windings on the secondary winding until the voltage is what you need.

Again knowing more about your current requirements would make for a better chance at the best solution.

Lefty

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