Decoded ESU V4 LokSound 73199, 73100, LokPilot 54650 and Atlas S2 decoders

[jdcolombo]

Thanks for the info, Pete.

The 73100 is clearly easier to add keep-alive to, especially if you want to add it to the first level (motor circuit). 

I haven't tried a 73100 yet, but now that I have dimensions, I might see if it will fit any of the locos I use (mostly GP9's and RS11's).

John C.

[RBrodzinsky]

I have been asked to put these into older Atlas GP38 and SD35.  Will document the process and fit (if it does — backup is wired Select Micro). Really not a lot of room in either.

[peteski]

Pete,
Thanks for the excellent and very clear explanation on the 73100 decoder.  Wonderful work that will help many of us.

You're welcome - I enjoy this facet of our hobby.

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.

That's fine. A agree with the ease of installation.

[reinhardtjh]

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.

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.

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.

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.

[peteski]

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.

It is pretty much about its mechanical design/layout.  Electronically it should be pretty much identical with the 73199 and other LokSound decoders.  I just need to edit couple more photos and do a small write-up. I was going to wait until I completed the write-up, but I was prodded a bit to give the keep-alive hookup info. 

[reinhardtjh]

Okay.  A layout gotcha I can deal with (I think).  Not so worried now.  Thanks!

[tehachapifan]

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?

[peteski]

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?

What physical size are those LEDs rated for 60mA?  The small LEDs (like 0402, 0603, or 0805) never come rated for 50ma.  The Chinese sellers often give inaccurate rating for their LEDs (sometimes they are way off removed from reality). Do you have a link to the LEDs you bought?  I'm really curiosu which LEDs are being sold as 60mA LEDs.

Regardless, LEDs are rated for their nominal operating current (the current at which they can operate continuously and at which their brightness is measured), and also for absolute maximum current or pulse current (which is higher than the operating current and which they will not survive for a prolonged period of time).  But the ratings are just guideline of what the LED can handle.  You (the designer of the circuit) have full control of the LED current with that current-limiting resistor you add in series (daisy chaned) with the LED.  SO even a 60Ma LED can be used at 5mA, 1mA or any current from zero to the nominal operating current.

So don't worry - those "60mA" LEDs will work just fine with a resistor which you normally use with your white LEDs and will only pass as much current as the resistor allows.  That resistor throttles down the LED current.

[tehachapifan]

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.

[RBrodzinsky]

Russ,

As Pete says, it is the resistor (and device forward voltage) that determines the current. As these are 3.1 volts, and using 12.5V for the source, a 1000 ohm resistor yields 9.4ma. A 680 ohm gives 13.8ma

I like to use the calculators at http://ngineering.com/led_calculators.htm

[peteski]

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.

Ok, that explains it. The 3014 LEDs are beefier than the tiny LEDs I mentioned earlier - these can withstand much higher current (60mA) but you can just as well use them at lower currents by choosing an appropriate resistor.

Like Rick said, regardless of the LED's current ratings, the resistor you will use determines the current which will pass through the circuit resistor and LED, since they are daisy-chained (or connected in series).  For all intensive purposes, you can use 3V as a standard forward voltage of the white LEDs we use in out hobbies.  Then just follow Rick's instructions (and like he said, there are many online LED resistor calculators).

None of this is very complicated.  It is a simple circuit (resistor and LED), and a simple, elementary-school level math.  No black magic involved. 

If you don't want to bother with calculations, a 1k resistor (with any size white LED) in a DCC environment will work just fine.  That is a typical resistor value used by many modelers.

[tehachapifan]

Ok, good info. Thanks, guys!

[RBrodzinsky]

Question on the LEDs on the 73199/54650 boards:

There are four LEDs (HL/RL/Aux1/Aux2) which are a warm white SMD right angle mount LED (rectangle with dome top).   I have searched both Mouser and Digikey for a similar one, but don't seem to be able to find a suitable match.

I am making up some different boards, and I like the color and size of these.  The right angle feature and dome top will make these ideal for my application. Currently looking at using either 0603 or 0804 SMDs, soldered on edge, but that is a PITA.

Does anyone know who makes these (or equivalent) LEDs, and if they are available from any retail distributors here in the US?

[Philip H]

Is someone keeping a running list of which locos these fit in without modification and what mods need to be made for others? Us unwashed technogeeks would really appreciate it.

[lashedup]

Other than the Intermountain locos that use the board directly, are there any others than can be done without frame mods?