Dcc how to get power to points and signals

muns

muns

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Yesterday I decided to try something.

My test rig consists of a MTS3/Navigator setup and an Analogue controller. Unfortunately, I do not have an AC power source in this.

So I connected the 51750 to the track output of the MTS3 central station, and one of the outputs to the motor on an ESU service board.

Pressing and holding the respective switch on the 51750 causes the motor to turn in one direction but with the inevitable "Motor connected to the DCC track whine".
Pressing the switch the other way. causes the motor to turn the other direction.

However, my Massoth Service Board, which is also in the loop, has LEDs indicating track and motor power. To my surprise, both LEDs on the motor are lit when applying power to the motor through the 51570! This seems to indicate that some of the unwanted DCC signal (the bit that should be blocked by the diode in the 51750) is passing to the motor.


So, with that, I swapped the motor for a LGB Switch drive and low and behold, it did not throw whine when operating the switch on the 51750 but it did whine!
 
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Greyfox

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Get yourself a basic voltmeter. Amazon.com: Extech Digital MultiMeter: Tools & Home Improvement

The $22 MN35 is fine.

Check the voltage on the track when you turn on your system. Set the voltmeter selector to the 200V AC when measuring.

You should see something like 18-22 volts. If that is the case then connect your 51750 power input leads to the track.

If that does not work, then just connect your 51750 to your old power supply.

The switch decoders would be needed only if you make the leap to use the Massoth DCC system to control the points and signals. In that case you would sell your 51750 on ebay. You could use the money you get from that to pay for your first visit to a psychiatrist because after a few weeks of DCC you will either go crazy or drink heavily.

Only kidding. DCC is great but can drive you crazy. then again, being driven crazy is why we do this. It keeps us down the basement away from the wife in the winter because we can't play golf.


Piko came out with a DCC system that I believe is a skinnied down Massoth. Here is a video that explains using switch decoders. Jonathan does a a good job with this and other videos. While it is not your exact Massoth system, the concepts are the same.

Drawing of track control
 
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Greyfox

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Transformer system
 
J

John S

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136674_ef1f131e9ea124b38a3fda90b9bb5864.png


136676_bd40de2a17c15c3fecb38ade479d4f11.png

136678_84242ef4af70fdeacba45dabd2658176.png
 
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PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
24,075
705
Tamworth, Staffs.
Excellent!

We now have enough information to provide a reason why 'what should work' doesn't, and a number of different ways to make it work..

Mark: Than you for that.
Mark has shown the diodes within the 51750 will not provide the rectification/isolation needed to drive the point motor.

John: Elegant solution.
Greyfox will have to decide if that is a solution he can afford / cope with connecting up.


My solution:

1. Use the Massoth unit to power the track and loco's ONLY.

2. Use the existing LGB 5006 to provide AC power to the switch boxes, and hence points and lights.
The transformer can be in the house (or wherever your Massoth etc. is located). This will use your existing wiring, and as you say, works.
This also keeps the two systems totally isolated, hence any faults within one system will not affect the other.

You may need a pair of wires from the 5006 to wherever your switch boxes are going to be located.

PhilP.
 
John Russo

John Russo

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Connect wires from the track to screw terminals 17 and 18 in the picture below.

I assume you the have (1,3); (5,7); (9,11); (13,15) connect to your points and signals.


 
Greg Elmassian

Greg Elmassian

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I'm referencing the confusion from the post below:

Yesterday I decided to try something.

My test rig consists of a MTS3/Navigator setup and an Analogue controller. Unfortunately, I do not have an AC power source in this.

So I connected the 51750 to the track output of the MTS3 central station, and one of the outputs to the motor on an ESU service board.

Pressing and holding the respective switch on the 51750 causes the motor to turn in one direction but with the inevitable "Motor connected to the DCC track whine".
Pressing the switch the other way. causes the motor to turn the other direction.

However, my Massoth Service Board, which is also in the loop, has LEDs indicating track and motor power. To my surprise, both LEDs on the motor are lit when applying power to the motor through the 51570! This seems to indicate that some of the unwanted DCC signal (the bit that should be blocked by the diode in the 51750) is passing to the motor.


So, with that, I swapped the motor for a LGB Switch drive and low and behold, it did not throw whine when operating the switch on the 51750 but it did whine!
I only see the results that should be expected.

The first test should be taking the square wave DCC and only sending positive pulses with one button, and only negative pulses with the other button. This should result in a noisy motor having widely spaces square wave pulses in opposite polarities. From what you wrote, this is exactly what happened. So far so good.

Where I get confusing is you have "both leds lit" when the motor is running. I assume these 2 LEDs are in parallel with the motor and in opposite polarity. You expresses surprise that both were lit. If the wiring is as I have stated, yes INDEED both LEDs should be lit, due to the innate BEMF in the system, one led is lit from the power applied to the motor, and the other led is lit from the BEMF FROM the motor.

You could confirm this by substituting a resistor for the motor, which has no BEMF.

So, if things are wired as I believe they are, your observations are exactly what should be observed. (especially with square wave pulses, which will generate the most BEMF)

Greg
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
24,075
705
Tamworth, Staffs.
I'm referencing the confusion from the post below:


I only see the results that should be expected.

The first test should be taking the square wave DCC and only sending positive pulses with one button, and only negative pulses with the other button. This should result in a noisy motor having widely spaces square wave pulses in opposite polarities. From what you wrote, this is exactly what happened. So far so good.

Where I get confusing is you have "both leds lit" when the motor is running. I assume these 2 LEDs are in parallel with the motor and in opposite polarity. You expresses surprise that both were lit. If the wiring is as I have stated, yes INDEED both LEDs should be lit, due to the innate BEMF in the system, one led is lit from the power applied to the motor, and the other led is lit from the BEMF FROM the motor.

You could confirm this by substituting a resistor for the motor, which has no BEMF.

So, if things are wired as I believe they are, your observations are exactly what should be observed. (especially with square wave pulses, which will generate the most BEMF)

Greg
The fact it will not drive a point-motor over (at least, as I read it) is a little surprising?

Without going back to the specifications, I could suggest a couple of reasons why this would be so. I suspect the frequency used to be the main problem?
(Unless I have interpreted Mark's observations incorrectly, of course).
 
Greg Elmassian

Greg Elmassian

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Back to the basic issue :) , it really should not be frequency per se.

Also, I would suspect that perhaps the diodes in the LGB box might not switch fast enough, as DCC, while of variable frequency (due to the constant modulation) has a frequency that sort of varies between 5 and 10 KHz ... pretty low frequency for a diode to switch, but again significantly higher than 60Hz, i.e. 100 times faster.

Just kind of basically not a good idea, since you cannot rely on the signal. Better off to use the recommendation to rectify the DCC to DC, and then either pulse the dc with momentary reversing switches, or if you MUST use the LGB box, back to AC 60 Hz (sorry in your case 50 Hz)

Greg
 
P

phils2um

Phil S
11 Sep 2015
384
172
Ann Arbor, Michigan
Thanks for the sketches!

OK, so it has been determined your wiring is correct :clap: and the LGB 51750 indeed does not like a track DCC signal as a quasi-ac power input:cry:. Apparently Mohammed at AllAboutLGB.com was absolutely right. John's solution on post #64 appears to me to be the best if you must use the 51750. He also wisely recommends the inclusion of electronic fuses for the track feeds to both of your LGB switch boxes.

Might I suggest instead that you move completely to the "dark side"? Relegate the 51750 to Ebay and purchase a DCC 4 channel switch decoder such as the Massoth 8156101 or LGB 55025 or 55525. The wiring all appears to be in place to use a DCC switch decoder as a "drop-in" replacement for the LGB 51750 switch box. This does mean you will need learn how set it up with your 1210. It should be relatively straight forward since you were able to get your locos running with DCC. And, this is something you will in all likelihood want be able to do in the future. You are only using four switch outputs (as of now!) so you can can leave the decoder set to its default DCC switch addresses of 1 through 4. No decoder programming necessary!

One advantage to the Massoth 8156101 over the LGB turnout decoders is that you can add momentary contact switches to manually operate your turnouts/signals if you decide you can't live without dedicated physical buttons. It will require some soldering and additional wiring but you "can have your cake and eat it too"! I suggest you download the Massoth and LGB manuals from their respective websites and see if this is how you might want to go.

Good luck with whatever you decide and keep us updated with you're progress.
 
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Greyfox

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In the above diagram, for 51800, are the two wires coming from the 1200Z connected on the the far right screw terminals shown in the photo below?

View attachment 258775
Hi All thanks for your help I have decided to run more wires out to 51800 and using a transformer to power the points as this at the moment seems best solution .have tented and massoth works the train fine and transformers sends power to points /signals .
 
G

Greyfox

Registered
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Excellent!

We now have enough information to provide a reason why 'what should work' doesn't, and a number of different ways to make it work..

Mark: Than you for that.
Mark has shown the diodes within the 51750 will not provide the rectification/isolation needed to drive the point motor.

John: Elegant solution.
Greyfox will have to decide if that is a solution he can afford / cope with connecting up.


My solution:

1. Use the Massoth unit to power the track and loco's ONLY.

2. Use the existing LGB 5006 to provide AC power to the switch boxes, and hence points and lights.
The transformer can be in the house (or wherever your Massoth etc. is located). This will use your existing wiring, and as you say, works.
This also keeps the two systems totally isolated, hence any faults within one system will not affect the other.

You may need a pair of wires from the 5006 to wherever your switch boxes are going to be located.

PhilP.
hi have only just got into massoth so there is a great big learning curve ,but what I noticed is that the navigator when slowing down and deciding to change direction navigator seems very slow to react as in transformer type of control is instant massoth is very slow and also stop button is sometimes not even working ,but the right hand stop works ok to shut whole system off ,to move train with navigator is very slow from start and when turning dial you get to halfway and train is only just trying to speed up .is there something I can change to speed up this action thanks Paul

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Greg Elmassian

Greg Elmassian

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8 Mar 2014
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www.elmassian.com
You posted this question in 2 places, 2 forum members answered on the other thread. It helps avoid confusion if you just put the question in one place (and also a gentle suggestion is start a new topic for a new topic, helps people see what you are asking)