Massoth eMotion XLS decoder's Servo Control Settings

LGB333

LGB333

Member
I would say yes, and if you are using a normal +5v regulator with a "straight through ground" you can hook the servo black/ground/- wire to the DEC- or you can use the ground on the output side of the regulator.

Do not try to "dim' an output to give you 5 volts.... don't even think about that... for an entire paragraph of reasons.

Greg
Okay, sage advice...….I ordered a six pack of the 5 volt regulators LM2596 DC to DC Buck Converted 3.0 - 40v to 1.5-35V Power Supply Step Down Module, the one shown in John's diagram in lower left corner, for $10.65 today.

The Massoth XLS Sound decoder installation instructions don't mention anything about having to use a 5 volt regulator to power a 5 volt servo like the Kadee #11220 Uncoupler in any of their information about using the decoder's A7 "Servo" connector. Maybe it's because the Massoth automatic uncoupler is a servo that uses 22 volts, so maybe Massoth didn't think about the need for guidance on using 5 volt servos which are the dominant type?
 
LGB333

LGB333

Member
A7 on the XLS is a solder pad on the underside.

The diagram below is for a XL, Note the connection of the Function output (A3 in this case, A7 on the XLS) connects to one of the "servo" pads on the underside of the 6v regulator board in order to use the onboard pull up resistor.


View attachment 248167

Thanks Muns - Yes, I've got all the instructions about using the Massoth XLS A7 connection for the servo. As I just mentioned to Greg, however, there's no discussion in the Massoth instructions about the need to use a 5 volt regulation for connecting a 5 volt servo. How did you discover the need to do so?
 
John S

John S

Registered
5 Nov 2017
457
269
Exeter, Devon, UK
Just out of curiosity, is this the same XLS as in post 1, as used for the Phoenix Solenoid?
 
Last edited:
LGB333

LGB333

Member
Just out of curiosity, is this the same XLS as in post 1, as used for the Phoenix Solenoid?
John - Yes, my original post was asking the basic question whether the Massoth eMotion XLS Sound Decoder could accommodate the Phoenix automatic uncoupler and/or the Kadee #11220 automatic uncoupler. Bottom line: Phoenix uncoupler no because needs the separate Phoenix controller; Kadee yes, if use with a 5 volt regulator to connect it.

Since the Massoth decoder's Installation and Configuration Manuals make no mention of needing to use a 5 volt regulator to connect a 5 volt servo, I wondering how everyone discovered this requirement? Certainly the Massoth documentation should be amended.
 
Greg Elmassian

Greg Elmassian

Registered
8 Mar 2014
2,212
589
San Diego
www.elmassian.com
I think the 5 volts is the requirement of the servo you chose, sort of saying it is your responsibility to power your servo with the appropriate voltage.

It might be that the power supply on the decoder cannot handle a lot of additional drain, or they don't want to share the 5v power (which usually goes to flash, ram and the microprocessor.

If you check out the Zimo manuals, they make an adapter board that the decoder plugs into and provides 5v for servos... they also show circuits with a 5 volt 3 terminal regulator added...

Everyone does it differently... perhaps it is a manufacturing decision... one less way to blow up their hardware if you provide the 5v.

Greg
 
John S

John S

Registered
5 Nov 2017
457
269
Exeter, Devon, UK
Part 1:
The regulator for using a Servo has been included in at least three separate documents from Massoth, XLS etc, Configuration Manual original version,the XL as in post #20, and in my own post #7 using Massoth's own product, and the earlier version of the XLS, using a 7805, http://www.allaboutlgb.com/pdfs/Massoth eMOTION XLS Decoder User's Manual V250.pdf.

Now Massoth may well have decided and concluded that attaching a regulator circuit or board directly to a decoder is inherently dangerous for powering a Servo, because, regardless of how you’re powering them, it’s worth noting that the current consumed by the Servo motor increases as the mechanical loading increases. A small Servo with nothing attached to the shaft might draw 10 mA, while a large one turning a heavy lever might draw an Ampere or more! If the power supply isn’t up to the task, a straining or stalled servo can cause the supply to sag, which may have other unpredictable repercussions, such as causing microcontrollers to reset.

Added to which, the vast majority of Servo's produced from Far Eastern sources, and not to put too fine a point on the subject, really are carp!, Massoth may have decided to, quietly drop mentioning the idea, probably due to so many decoders being returned for repair, and in line with other decoder manufacturers revamped and reintroduced this, 8152501 eMOTION 8FS Servo Decoder – Massoth Elektronik GmbH

Referring again to post #7, I showed an example of a DC to DC converter, I deliberately omitted "how to connect it to the decoder", my own view is to keep the supply for a Servo well away from the decoder, if you look at this example, Shourt Line - Soft Works Ltd. - Products - SL-6102104 Mini Gold Cap Buffer 2.5 Farad 10.7 Volt - UPS for analog train LED lights, the parts can be very easily sourced, DC to DC Converter, Bridge Rectifier to construct the same item for less money, power in, is taken directly from the DCC Track Input, regulated down to 5V for the Servo, only connection now will be the Servo Signal wire via a 1K pull up resistor to the decoder output, (if required, depending on which Massoth decoder and which Function Output, and whether the Servo behaves or misbehaves), the power source for the Servo is separate and independent from the decoder.

One last observation, I have no idea what the Servo is in a Kadee Coupling, I would hope for the money paid for it, it's a Digital Servo with Metal Gears, and not some piece of Far Eastern junk, but regardless of that, a 104 Capacitor should be fitted across the POS and NEG 5V OUT on the DC to DC Converter, Servo's are finicky devices at the best of times, and it is imperative to keep the Servo input supply voltage free from "noise" that can upset the Servo's internal electronics.

Part 2:
Solenoid Uncoupler
115529_ba37c83651231623c64b793c8c776459.png


Some detective work, obtained (on the right) remarkable similar to those on the left which are fitted to the Phoenix Uncoupler.

Still awaiting a email reply from Phoenix regarding a query I sent them about the specifications of the Solenoid that is fitted to their uncoupler, the two on the right which I do have the specifications for "could" be connected directly to a reinforced output on a decoder, as to whether this is the best option, probably not, would prefer an auxiliary method to isolate the Solenoid from the decoder.

Returning to post #1, I do not see any mention of a "snubber diode" fitted? Rather a critical component to be omitted..... a Solenoid "must" be treated exactly the same way as connecting a Relay.
115719_0ea7995ca5c5b2b2589dfe7b07a330b7.png

When the coil is de-energized, the "field" around it collapses, this unwanted energy requires to be dissipated safely to GND, reading post #1 this would have flowed straight back into the decoder vai a unreinforced 10ma A7 Output, result "probably" destroyed the output transistor, I say probably, because as the output is only 5V @10mA, would it actually have been able to energize the Solenoid in the first instance.

The A4 Output could well have powered the Solenoid, again no mention of a "snubber diode", plus no mention of an "on time" for the Solenoid, which should be pulsed in "parts of a second", anything between 3 and 5 seconds "on" time is likely to destroy it, again when de-energized "field" collapses, flowed straight back into the A4 Output.

First course of action, now would be to test the A4 & A7 Outputs, including any +22 and GND connections used when installing, and fingers crossed, perhaps a touch of the "Irish" and perhaps the Outputs survived........
 
Last edited:
John S

John S

Registered
5 Nov 2017
457
269
Exeter, Devon, UK
Had a tinker with this, have no intention at the present to pursue this further, maybe later on in the year, the 3D printer is somewhat overwhelmed at the moment and for the foreseeable future.

Can indeed successfully operate a Solenoid from a Massoth XL Decoder, and as long as the criteria as per the A3 output can be replicated on other Massoth decoders, will work fine.

At some point will look at this again, we already have Micro Servos working Hook & Loop couplers, be an interesting Winter project to adapt the existing STL files for the 3D printing, to see whether it is practicable to use a Solenoid in place of a Micro Servo, anyways all the bits have arrived for the turntable project, will keep me amused for some time to come...................

116867_d754048b12d77f0d9446112501d4bc5c.png