The Digitrax UR90 IR receiver panel has a 12 volt DC input receptacle and the instructions say that a 12 volt power supply is necesssary to operate the unit.
In my enthusiasm to set up the club UR90’s and demonstrate IR control using an unthethered UT4 throttle to club members for the first time, I connected the panels to the loconet but forgot to connect to the PS12 power supplies. However the demonstration was successful, including being able to control a loco while bouncing the IR signal off walls, ceiling and floor without a direct line of sight. The green and red LED’s flicked on and off as would be expected.
Were we drawing power through the loconet or were we missing a function that is enabled by 12 volt power? We’ve since connected the PS12’s but I’m still puzzled.
PS: The problems previously posted about locos bolting when programming and other funny programming glitches seem to be behind us, thanks to those forum members who responded.
Yes, if you didn’t have the power supply for the UR90 plugged in, you were indeed drawing its power from LocoNet.
There are no additional functions provided by the 12 volt power supply, other than to specifically power the UR90. Not using the 12 volt power supply, however, can greatly reduce the number of throttles you can use at a time, by reducing the amount of power available on your LocoNet, and, as the voltage drops lower and lower, could cause your LocoNet to act unpredictably.
Generally speaking, you want to avoid using LocoNet as a power source as much as possible.
You need only buy a 12V wall wart from Radion Shack, no more than $7.00. In order to use the DT300 and 400 as IR transmitters, you also need to put a 9V battery in the throttle. Just remember to take it out if you don’t use the throttles for a week or more. There are dissimilar metals in there and the electrolysis will “get” the contacts.