Lenz LS150 AC Power Supply

Model Railroader Electronics and DCC
1

I am using a couple of Lenz LS150 turnout decoders and have a couple of questions concerning the AC supply that is not totally clear from the manual…

Is it possible to power two LS150s from the same transformer? The manual is clear that the common “C” outputs should not be connected together, but makes no mention that the AC supply must be unique for each unit.

The manual does mention that for manual pushbutton wiring for switch machines, the common connection to the pushbuttons must be wired to the AC power terminal that is furthest from the corner of the board. If it is allowable to power two LS150s from the same transformer, I suspect that the connections to the transformer must be wired to the same terminals on the LS150s.

The other question is regarding maximum voltage. The manual just says that 16 V is the maximum. I am using a Hammond doorbell transformer rated at 16 V and 40 VA. With no load on the transformer, its voltage is more like 19. The manual does mention that if a transformer has a VA rating over 45, then a 10 ohm resistor should be used to limit current. I am wondering if a resistor should be used in my case. The units work fine with this voltage, but I am wondering if it will take its toll over time (things generally are engineered to take maximums over their documented values, but performance or lifespan may suffer).

2

I will find out in a week or two - a friend who’s layout I help out on has chosen to use LS150’s to drive his turnout motors. I hooked one up this weekend and it works great - he already has a 12VAC bus run around his layout to power accessories so the second one will tap off that same bus.

The purpose of the limiting resistor is to restrict current through the decoder if one of the outputs is shorted and activated. It can’t hurt. I would see if you can find a similar rated transformer but with a voltage rating of 12-14 volts - with little or no load it should be around 16 so as to not exceed the LS150’s input rating. If you won’t be powering more than the LS150’s from it, there will likely be very little load on it except at those times you actually activate one of the outputs.

–Randy