Trelothen - a Cornish fishing harbour

[Stubby47]

31 minutes ago, Andrew P said:

I've followed what you've done, and I can't see what is wrong with what you've done, basically it should work!

 

Could it be because the drive fulcrum has not travelled the full distance,  so the motor is still connected to the original polarity?

[Andrew P]

17 minutes ago, Stubby47 said:

 

Could it be because the drive fulcrum has not travelled the full distance,  so the motor is still connected to the original polarity?

That does sound like a possibility, but still strange.

[Donw]

When I used Tortoise motors to power crossover one for each turnout  I had no problems 

 

16vc supply two diodes connected to one side of the supply one forward one reversed gave two bus line pos halfcycles on one neg half cycles on the other

The other side of the 16v supply connected to a common return

A simple SPDT changeover for each crossover or single turnout the comon connected to the tortoise motor(s)   the NC and NO contact connected to the the pos half cycle bus and the Neg half cycle bus

The other motor contact connected to the common return.

witch thrown one way pos half cycles through the motor switch thrown the other way Neg half cycles through the motor.

I added a bipolar LED so that pos half cycles LED green Neg half cycles LED red.

 

Not tried this with Cobalts.

 

Post a diagram of how you have wired the Cobalts and the switches and we can see where the problem might be.

 

 

Don

[Stubby47]

Problem fixed - mostly.

 

Turns out despite not being able to see an issue, the 15 pin D had a short. This was obvious when I turn the power on as the Clipper was intermittently buzzing.

 

So, I've cut the 15 pin D off and added just a 9 pin to the Points cable. Sorted a 9 pin socket for the baseboard and now 2 of the 3 cross-overs work fine. Not sure on the third but I suspect a mis-connected wire in a choc block.

[Andrew P]

3 hours ago, Stubby47 said:

Problem fixed - mostly.

 

Turns out despite not being able to see an issue, the 15 pin D had a short. This was obvious when I turn the power on as the Clipper was intermittently buzzing.

 

So, I've cut the 15 pin D off and added just a 9 pin to the Points cable. Sorted a 9 pin socket for the baseboard and now 2 of the 3 cross-overs work fine. Not sure on the third but I suspect a mis-connected wire in a choc block.

See, we knew you could do it, well done, and I bet your relieved now.

[treggyman]

Hi Stu

 

I agree with Andy above.......

 

That's how I wire both my Tortoise & Cobalt motors  & they always work fine.....

 

Don't see what you've done wrong.....

 

Incidentally if your on off on switches are DPDT the wiring would be the same so the problem would also be the same.

 

Post now irrelevant as hadn't read above post before posting

 

Cheers Bill

Edited August 28, 2021 by treggyman
To add sentence

[St Enodoc]

8 hours ago, Stubby47 said:

And that's not worked either.

 

The more I think about this, the more I realise that ON-OFF-ON DPDT switches, as recommended in the Cobalt instructions, just won't work.

 

As soon as one switch is used, as the motors are stalled, they will still pass power through. So a 2nd switch immedately causes a short.

 

What a waste of time.

 

I can use (ON)-OFF-(ON) switches, but I lose the physical indication of the point settings.

 

Somewhat p'd off.

I don't think that's right. The permanent, as distinct form momentary, switches are the right ones.

6 hours ago, Stubby47 said:

Problem fixed - mostly.

 

Turns out despite not being able to see an issue, the 15 pin D had a short. This was obvious when I turn the power on as the Clipper was intermittently buzzing.

 

So, I've cut the 15 pin D off and added just a 9 pin to the Points cable. Sorted a 9 pin socket for the baseboard and now 2 of the 3 cross-overs work fine. Not sure on the third but I suspect a mis-connected wire in a choc block.

That's more likely. Keep the original switches.

[Stubby47]

There is movement !!

 

 

[St Enodoc]

16 minutes ago, Stubby47 said:

There is movement !!

 

 

You're a braver man than I, Gunga Din, driving towards an unprotected baseboard end like that!

[Stubby47]

Only driving slowly, although the temp wiring made the direction on the Clipper opposite to the direction of travel.  

 

If you turn the volume up, you can hear the Cobalts buzzing away when idle, I'm still not sure this is correct.

 

Each motor also has a 6-12v or 12-18v option, but on the 6-12v setting the motors are really too slow, although quieter.

 

I have a dc step down unit so I might try that to see if it helps.

 

Next is to finish off the wiring for the uncouplers, then I can turn the board round and lay the sidings.

[St Enodoc]

13 minutes ago, Stubby47 said:

Only driving slowly, although the temp wiring made the direction on the Clipper opposite to the direction of travel.  

 

If you turn the volume up, you can hear the Cobalts buzzing away when idle, I'm still not sure this is correct.

 

Each motor also has a 6-12v or 12-18v option, but on the 6-12v setting the motors are really too slow, although quieter.

 

I have a dc step down unit so I might try that to see if it helps.

 

Next is to finish off the wiring for the uncouplers, then I can turn the board round and lay the sidings.

The Cobalts definitely should NOT buzz when idle (or at any other time). I'd suggest getting a regulated dc supply. They cost about $20 over here, so you should be able to find one for a tenner or so.

 

What variety of Cobalts are these? The latest ones should work properly on anything between 9 and 23 V dc.

 

 

[Stubby47]

Thanks for confirming that.

 

I've got units similar to your Wheel Veronica uncoupler, so I just need to wire one in, inside the control panel.

 

I can then adjust the output power to get the fastest movement without the noise.

[JustinDean]

Just going to throw in a question about the Cobalts and switching having just read through your issues but I’ll also add I’ve not used Cobalts myself.

Does the Cobalt only need power whilst switching the point blade? If you’re using non momentary DPDT switches won’t they be continuously be providing power to the Cobalt even when the point has been switched hence the buzzing?

 

Jay

[Stubby47]

4 hours ago, JustinDean said:

Just going to throw in a question about the Cobalts and switching having just read through your issues but I’ll also add I’ve not used Cobalts myself.

Does the Cobalt only need power whilst switching the point blade? If you’re using non momentary DPDT switches won’t they be continuously be providing power to the Cobalt even when the point has been switched hence the buzzing?

 

Jay

 

Yep, they are a 'stall motor' design and are supposed to be continually fed power. But either I'm giving them too much power or they aren't travelling far enough each throw.

 

Just need a bit of electrickery and some fettling.

[bgman]

6 hours ago, St Enodoc said:

The Cobalts definitely should NOT buzz when idle (or at any other time). I'd suggest getting a regulated dc supply. They cost about $20 over here, so you should be able to find one for a tenner or so.

 

Hi Stu,

 

I would agree with the above having used many variants of Cobalts in the past. A decent power source is a definite must whatever you decide to power.

 

I have since gone over to servos using Dave's Megapoint system which is powered from a regulated power unit and it works as it should.

 

Hope you manage to get it sorted mate.

 

G

[Keith Addenbrooke]

9 hours ago, St Enodoc said:

You're a braver man than I, Gunga Din, driving towards an unprotected baseboard end like that!

 

Indeed - this actually happened to me today:  I’m working on a small scenic test track and connected up the controller for a test (DC, just two wires).  Engine* behaved itself perfectly when the controller was set for Forwards, but the moment I flicked the switch to Reverse it instantly set off at full speed - even though the power was still at zero!

 

No way I’d have prevented a high-speed drop test on a layout like Trelothen.  Fortunately (as @The Stationmaster and others will know), I strongly favour continuous run layouts, so was able to catch the Engine as it came around. Not sure what I’d done, though disconnecting and reconnecting the controller fixed it.

 

(* I’ll use the term Engine rather than Locomotive as it was just a ‘naked’ powered chassis with no body).

Edited August 29, 2021 by Keith Addenbrooke

[treggyman]

2 hours ago, Stubby47 said:

 

Yep, they are a 'stall motor' design and are supposed to be continually fed power. But either I'm giving them too much power or they aren't travelling far enough each throw.

 

Just need a bit of electrickery and some fettling.

Hi Stu

 

As far as I'm aware as soon as the motor can travel no further it should stop whether it has completed it's full travel or not.....Hence the name stall motor.....

It should certainly not buzz once it has completed it's throw.......

I may be wrong & am quite happy to be corrected but that was how they were sold to me....

If you have a spare one try wiring it up without fitting it to the point & see if it buzzes when power is applied & it reaches the end of its travel/throw.....I've just tried it with a spare Tortoise motor & restricting the throw stops the motor but no hum/buzz only the sound of the gears when the motor is actually moving....

My power source is nearly 40 year old H & M Duette.

I'll leave it on with restricted throw for a while & see what happens ie if it gets warm or not....

 

Cheers Bill

[JustinDean]

Just to reiterate what Bill has said above I’d remove the motor and test to see if it actually stalls as it should. If power is constantly applied and the motor is still operating there’s a risk of damage. Maybe worth looking up if you can adjust the switching point on the motor where the it stalls to match the throw of your point?

 

Jay

Edited August 29, 2021 by JustinDean

[treggyman]

Hi

Well the motor has been 'Stalled' for 3/4 hour now so I would have thought that if it's going to have an effect it would have happened by now....

The motor has not heated up....

There is no buzz/hum other than a faint electrical noise that you have to put your ear close to the motor to hear....Exactly the same noise as when the motor has travelled full throw in normal use......

 

In restricting the throw the power is on full.....

The motor can only travel less than a third of it's allowable travel.....

 

As I said this is a Tortoise point motor but as far as I'm aware the working principles of Tortoise point motors & Cobalts i assume are the same.....

 

I'll leave it a while longer to see if any change occurs......

 

I had heard that Cobalts can be noisier than Tortoise motors but I had assumed that this only related to when they were moving not when stalled.....This in my experience I would agree with......

The Cobalts I have are silent when thrown but I've not got one to do the same test as I'm doing on the Tortoise motor.....

 

Hope this helps

 

Cheers Bill

[Stubby47]

27 minutes ago, JustinDean said:

Maybe worth looking up if you can adjust the switching point on the motor where the it stalls to match the throw of your point?

 

Hi Jay, that's part of the planned fettling process. I've not yet glued the pivot hole plates in place, so can adjust them so the arm throws as far as possible.

 

Plus using the regulated supply, it should all be sorted.

 

Two positives: all the points throw as planned on the panel diagram and all the track polarities were correct first time.

[Stubby47]

Thanks Bill, very good of you to experiment on my behalf.

 

I'm sure I can resolve this - these motors are new to me so it's just a learning curve.

[St Enodoc]

5 hours ago, bgman said:

A decent power source is a definite must whatever you decide to power.

 

1 hour ago, Stubby47 said:

Plus using the regulated supply, it should all be sorted.

I think this is the key.

[Donw]

Well to start with the are various models of Cobalt they origninally had a low stall current but didn't like higher voltage so much. A replacemnt type was happier with a higher voltage but drew more stall current about 60mA I believe the newer ones IP I think have circuitry which detects the stall and then reduce the supply to reduce the stall current . Which ones do you have.

 

Tortoises seem to have a inherrently lower stall current.

 

Servos can have there own issues but can work out cheaper depending on the servo driver you use.  Note Servo are best with short leads . Servo drivers that can handle just a few servos can be placed around to keep the leeds short.

 

Don

[Stubby47]

The Cobalts are the Omega variety, as I don't need the additional complexity of the DCC ones.

 

I tried using servos with MERG control boards on T-CATS. I found the initial shuffling (chatter) on power up could affect the setting of the point, plus I had an intermittent failure where the servo didn't respond.

[Stubby47]

Small pcb thingy wired in and adjusted so the points move.

 

I still have buzzing from all 6 motors, at a low level, and I think the 6 combined, plus the baseboard itself, are contributing to the overall noise.

 

I can always introduce an on/off switch into the feed circuit to only be used when changing points.