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Pete,Thanks for the excellent and very clear explanation on the 73100 decoder. Wonderful work that will help many of us.
I am thinking to use the stage 1 for additional caps on this decoder, purely because of the relative ease of access for the soldering iron.
Judging by the info imprinted on the circuit board (the part number and the date) this decoder is a precursor of the 73199. The date seems to indicate that it was designed in 2015 (73199 shows date of 2016). So even though the 73199 was introduced first (originally factory installed in Intermountain SD40-2, then made available as a separate item), the 73100 appears to have been designed first, but made available only after 73199 was released.
As I mentioned earlier, going by the year imprinted on the ESU circuit boards, the 73100 was designed a year earlier than the 73199. I see few things that IMO were not optimal on the 73100 and I see some of those have been addressed on 73199. I will add this info soon.
Members here related information from both IM and ESU in the years before the SD40-2 finally appeared indicating that there were multiple attempts from ESU to create the decoder finally used. I wonder if the 73100 is a version of one of those that didn't make it.I'm looking forward to finding out what you found as I have a small pile of 73100's to use and I hope it's nothing too critical. Plus the form of the 73100 seems to fit better in the frames I'm looking at.
I noticed on the 73100's packaging that the function outputs on these are rated at 50mA. I ended up purchasing some 60mA SMD LED's by accident, instead of 20mA ones (I installed a couple 60mA ones in a LL SW1200 with a Digitrax decoder that apparently has outputs rated at 500mA, so all is working OK so far in that unit). Regarding output ratings, what might happen if one or two 60mA LEDs with resistors get attached to a 50mA output? Would there be excessive heating, is the decoder itself in any danger, or are the LEDs simply not going to illuminate as bright?
Thanks, Pete! That eases my concern. That said, I've never been very good at calculating required resistor values. I've always gotten by OK with simply using a 1/4 watt resistor between 680-1K Ohms (when I'm [normally] using a SMD LED around 20mA). Can't recall now how I arrived at that. Not sure if these resistors would be adequate enough with a 60mA (3014) SMD LED running from one of these 50mA outputs. Yes/no? The 60mA 3014 size SMD LED's I got this last time around were from Digikey and the part number is 1416-1216-1-ND. I like this size as it will cover both lenses of a typical headlight, the lighting surface extends to the edges of the package and they're a size that makes attaching leads pretty easy.