CT DCX65/5 Decoder Info

[narrowminded]

After searching to no avail I am trying to find CT DCX65/5 decoder information.  They list the DCX 65 as a low voltage decoder specifically for 3-8V motors and then, they list another with the suffix /5, a DCX 65/5V.   Both share the same listing with all information identical except for one line in the specs towards the end of the page.  It states the DCX 65 is "Version with 6 connecting wires" and the DCX 65/5V states that it's "Version with 6 cables and Lv and Lh as logic output".  What does this mean?

Elsewhere in my searches I found reference to "T" scale for the /5 version but nothing about what it is, what it does, or why?

Here's the link to CT's site and this page.  http://www.tran.at/Produkte/DCX65.shtml  Use the translator if it's in German.

Edit Add:  Found this.http://www.tran.at/Dokumentation/DCX65.pdf  It's in German but does show a difference in a wiring diagram that mentions the two versions.  It seems that maybe there's an onboard voltage limiter for 5V... maybe?   I don't know.

[peteski]

After searching to no avail I am trying to find CT DCX65/5 decoder information.  They list the DCX 65 as a low voltage decoder specifically for 3-8V motors and then, they list another with the suffix /5, a DCX 65/5V.   Both share the same listing with all information identical except for one line in the specs towards the end of the page.  It states the DCX 65 is "Version with 6 connecting wires" and the DCX 65/5V states that it's "Version with 6 cables and Lv and Lh as logic output".  What does this mean?

Elsewhere in my searches I found reference to "T" scale for the /5 version but nothing about what it is, what it does, or why?

Here's the link to CT's site and this page.  http://www.tran.at/Produkte/DCX65.shtml  Use the translator if it's in German.

Edit Add:  Found this.http://www.tran.at/Dokumentation/DCX65.pdf  It's in German but does show a difference in a wiring diagram that mentions the two versions.  It seems that maybe there's an onboard voltage limiter for 5V... maybe?   I don't know.

T scale is a fairly new (and not very widely popular) scale. 1:450 I believe.  Tiny!  https://en.wikipedia.org/wiki/T_Gauge
I have briefly looked at those decoders and as you say they are designed to operate on low voltages and control low voltage motors.

"6-connecting wires" or "cables" likely means that it is the standard NEM651 6-pin interface (like any other decoder).  Just track power, motor output and headlight functions (with no blue wire).

"Logic outputs" likely means that those function outputs are not designed for directly driving electric loads (like LEDs or other devices). They can only supply or sink  logic-type value current (very low).  To use them in a conventional way you would have to add a buffer (usually a transistor) which would convert logic-level to standard higher-current function.

[narrowminded]

Thanks @peteski .  Looking at it a little further it seems to be about lighting only, not motor output.  But that's not clear to me.  

It got me to wondering if it could be something to do with lighting and not overpowering existing led/ resistor combos when running on straight DC.   That's an ongoing problem for them, no English language support.  It makes me wonder what in the wide, wide, world of sports they're thinking with the nature of the business they're in.  

Independently people have fixed that problem with their own English explanations for the general application as it's one standard program but this one seems to be unique in that /5V thing and I haven't yet found an explanation of that detail in English or German.  The unnecessary time I've burned on this wants me to send them a bill for their gross negligence in this matter.  It's frustrating and aggravated by my own lack of expertise in electronics but it doesn't have to be that way if they'd just respect their (potential) customers and put together a couple of sentences explaining the damn difference.

[peteski]

Yes, function outputs (standard or logic level) could be used for lighting or whatever esle you want to connect to them.

Partial translation (by google) of the web page for that decoder shows:

The locomotive decoder DCX65 is suitable for all 3-8V DC and AC motors in T to N locomotives. The maximum total load must not exceed 250mA.

The DCX65 offers high-frequency 16kHz or 32kHz motor control for Faulhaber motors. Alternatively, infinitely adjustable 30-150 Hz are also available for traditional motors.

Also:
Rail voltage 7 - 21 V
Maximum motor current - peak (3 s) 400m A
Maximum motor current - duration 250m A
Maximum current of the function outputs 250m A
Maximum total current of the decoder - duration 250m A

[narrowminded]

Yes, @peteski .  I was able to get that much using the translator and it also seems to be identical to all of their decoders, high frequency, low frequency, and all, with the only real exception being the smaller maximum load and a lower supply voltage rating.  That supply rating allows for 7-21 V where others are rated at 10-19V.  So far, so good.  Meanwhile, I have already tested motors a few years ago supplying 6V to their 76D decoder and it all worked fine.  In fact, that was my first experience using a decoder of any sort. 

And the claim has always been that high frequency PWM can be used to lower max voltage to run a lower max rated motor.  My own experience is a qualified yes with the qualifier being that it's not immediate but a higher supply voltage, even reduced through high frequency PWM, does take its toll on the smaller coreless motors with metal on metal brushes, and that toll surfaces in brush life.  They didn't like the higher voltage, even though pulsed to reduce the average, and high frequency to further improve the effect on them was an improvement but wasn't a fully satisfactory solution.  What IS of note and wasn't a problem, whether high frequency or low, was any pulsed power as long as those pulses were derived from a power source no higher than the rating of the motor.  It wasn't the pulses or their frequency, it was the voltage of those pulses. 

And it's all of this experience that has me so interested in how this decoder's ratings are being arrived at and whether they have any benefit for my purposes.  It seems not.   The only real benefit this decoder has as I'm understanding it is the smaller envelope dimensions, none in performance or how it gets to that end.  I wish I could be sure that this IS the true story and I wish I knew what in the hell the /5 suffix is, although at this point I'm thinking it has nothing to do with motor voltage so is outside of my known motor voltage interest.

In summary, so far, I don't see any difference in how this decoder delivers anything different to any motor connected to it as long as the motor draw is below the 250mA rating.  It does not internally reduce the max voltage and therefore is no different up to the 250mA limit.  Does that seem like a fair understanding?  It does allow for smaller components and therefore a physically smaller decoder but in function, below 250mA, there will be no difference whatsoever. 

[peteski]

You make good points Mark.  I cannot tell you for sure how they supposedly limit the motor voltage with much higher voltage is being feed from the track.  Only way for sure would be to check the motor output using an oscilloscope (whcih I own, but I don't have the decoder).

I also agree that it is highly doubtful that they step down the motor voltage using some on-board voltage regulator (not just using PWM of the full rectified voltage from the track).  That decoder seems way too small (physically) to have an additional voltage regulator on-board.

If you are worrying about damaging the low-voltage coreless motors with a higher voltage PWM signal, and this is just for your layout, you could just lower the track voltage coming out of the DCC booster.

[narrowminded]

Thanks again @peteski .  This interest is based on the desire to have a unit capable of running on a standard layout with standard voltage and all accomplished without using any space, mainly because there isn't any space in some of what I want to build.   Lowered voltage schemes are many and I've experimented with just about all of them.  They work fine but they either have to have the whole track limited or if included on board, consume valuable space that's just not available at all or better used for weight.  

And my frustration isn't that what I wish for doesn't exist or that this latest piece from CT isn't really any different but for the size, but that the very easily furnished information to confirm this doesn't exist and the amazement at this company's ability to continue this lack of normal information as a long term theme.  They DO have the smallest stuff available and my limited experience says when running the performance is quite excellent but that just makes the whole lack of reasonable support that much more baffling.  It seems that they exist in spite of themselves.

[DavidMatthewson]

Hi Guys

A bit of background on this.. I've used these in T gauge stuff - 1/450 scale - one needs small fingers, bright light, magnifying 'specs & patience but they do work...

See:

https://www.tgauge.com/product/395/0/250ma-5v-decoder

http://www.talkingtgauge.net/viewtopic.php?f=10&t=525

Usual disclaimer - just another customer..

best wishes

David

[DavidMatthewson]

Data sheet attached