Bill..... The bulb, if wired correctly, is doing exactly what it is supposed to do. It stops the power booster's internal circuit breaker from shutting down the entire layout if a short circuit occurs on just one turnout. Thus, the remainder of your layout is still operational even though there is a short (derailment or grazing wheel on open point) on a turnout.
The nature of the bulb is that the filament has a very low resistance when cold and a very high resistance when hot. With no short, it is the same as a piece of plain wire. With a short, the bulb lights up and the filament gets hot and the bulb becomes a giant resistor. This additional resistance causes the current drawn from the power booster to be reduced to an acceptable level. Thus the power booster's internal circuit breaker does not open and the rest of the layout is still able to keep chuffing away. The circuit breaker built into the power booster does have a problem with sound decoders due to the large inrush current that charges the capacitor on the sound decoder. The power booster cannot determine whether that large inrush current is a short circuit or a sound decoder being charged up. It all looks the same to the power booster's internal circuit breaker. The circuit breaker is just doing its job which is to protect the power booster from an overload condition which might damage itself or melt flanges. If you do not like the inexpensive bulb "solution", the more sophisticated approach is to use a DCC Circuit Breaker like the PSX-1 made by DCC Specialties and sold by Tony's Train Exchange. This little device, while costly, is smart enough to distinguish between a genuine short circuit and a charging capacitor. It acts faster than the circuit breaker built into the power booster. Thus, the remainder of the layout can still function in case of a derailment. A cheaper solution is to make sure all wheels and track are gauged properly to NMRA/NASG specifications. Then those pesky metal wheels will not graze the open point and most momentary short circuits become history. Hope this helps.....Ed L. --- In [email protected], "Bill Lane" <bill@...> wrote: > > I did not think of the bulb as a circuit breaker. I do have them already > installed as per a NCE diagram. The circuit breaker would not reset if the > only loco in that power region used a sound unit. I guess the bulb produced > some sort of load to reset the breaker where the Tsunami did not. I would > have much preferred that NCE fixed the circuit breaker issue instead of > having to resort to this bulb fix. > > > > In spite of some new found knowledge on the subject I am not going to reply > on the "bulb" as my sole source of short protection for my DCC system. > > > > Thank You, > Bill Lane ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
