I am in the process of wiring my layout. I'm using Digitrax BDL168 for block detection and SE8C for signaling. (An added bonus of the SE8C is that it functions as a stationary decoder allowing control of Tortoise machines from the hand-held throttles and also allows simple wiring of momentary push buttons on the fascia to throw or close switches manually. Those added bonuses are nice, but are not the topic for this thread.)
I'm using NJI signals. They have a resistor attached to the tiny magnet wire leads. I'm also using Digitrax TSMK signal base terminal strips. The TSMKs have resistors built in to the circuitry of the boards. The general rule is that (appropriate) resistors in the leads are required to protect the LED lights of the signals and control/match the brightness of the lenses. Is it okay to have two sets of resistors? I'm not sure exactly how many ohms are provided by the NJIs or by the TSMK, and I'm not sure how many are required, but I'm hoping some of the regular posters on this forum are familiar with these particular items and can give me specific advice what to do. I'd rather not snip off factory-installed stuff until I have a firm grasp of the details, and even then I'd prefer not to do any painful snipping unless it is really necessary.
Thanks.
Robert
LINK to SNSR Blog
The combinatiooon will be too much. The NJI signals have resistors PROBABLY appropriate for operating on 12V. It should be documented somewhere. The SE8C drives the signals at 5V, but even more so, it uses a 'trick' called multiplexing where in reality is it flashing the signals ona nd off rapidly - that's how each of those 10 wire cables can drive 12 or more LEDs - and 2 of the 10 wires are a +V and GND. That means they need a smaller resistor than would be used if they were just on constantly, to appear at the same brightness. The resistors built in to the Digitrax terminal strips are the proper size for most LEDs when using the SE8C.
If both sides of the resistor ont he siognals have exposed portions of the lead wire, you can test thusly; Hook them up WITH the resistor - I suspect they will either not light or be very dim. Then try using a jumper wire around the resistor. It should then light as expected. You can also try witht he NJI resistor in the circuit and bypass the resistor on the Digitrax strip, but those are surface mount resistors and it's hard to hold a jumper in place to bypass one.
One or the other resistor MUST be in the circuit - no resistors at all will either burn out the LED or damage the port on the SE8C or both. My educated guess is that the NJI resistor is too big, and the Digitrax supplied ones on the strips are the correct ones.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I put 12DC into their LED signals with the supplied resistors. the wire without the resistor is the 'common'. If you are using a separate power supply, why not drop it to 9V, if possible.
From the NJ international website
All NJ LED crossing signals, block signals, and signal heads contain 3v common anode LED’s. Dropping resistors are factory installed to protect the LED’s and it is recommended to use 9-14v DC power.
If you have any issues, why not drop them an email and ask them ot call them
Ph: (813) 406-4288
info@njisignals.com
Good luck!
Neal
nealknows If you have any issues, why not drop them an email and ask them ot call them Ph: (813) 406-4288 info@njisignals.com Good luck! Neal
Hey thanks, Neal-
Good idea. I pretty much copied-and-pasted my OP and e-mailed it to NJI. We'll see what happens next.
Well that information seals it - you need to bypass the NJI resistors to work with the Digitrax mast terminals which already have resistors.