Tortoise 16v AC circuit problems

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 13, 2023 3:29 pm

Thanks folks - useful learning process, for others too hopefully. Remember I had no idea about how to use a meter. I'll be along soon with some readings from the 50VDC setting, and I'll try the test light as a resistor. But Martin yes I'm sure the reading is up around 30 while the motor moves, very slightly lower on the unused motor. The needle moves up towards a high point and then drops back as the throw ends. I qualify everything I say with "if that makes any sense" as it may not.

Alan the photo from last night is not how I set it all up this morning for your test. I did follow your instructions except I didn't do any more soldering to the microswitch terminals, rather, I re-arranged the wires into another terminal block to follow the routes as you described. TBH I thought you might be steering me to see that I'd wired this wrongly (parallel/series?).

To give folks reading a(nother) laugh, I'll ask whether rosin is the same rosin as string players (violin, cello, etc) use on their bows (to stop the hairs simply skating over the strings). I assume not.

Tony Wilkins
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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Mon Mar 13, 2023 3:41 pm

Hi Julian.
Rosin or Resin flux are two names for the same thing and I use Carr's Orange label if I need a bit extra for a wiring solder joint.
Whether its the same or similar to that used on bow strings, I have no idea, but it wouldn't surprise me if they come from a similar source.
Regards
Tony.
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Will L
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Re: Tortoise 16v AC circuit problems

Postby Will L » Mon Mar 13, 2023 4:04 pm

Tony Wilkins wrote:Hi Julian.
Rosin or Resin flux are two names for the same thing and I use Carr's Orange label if I need a bit extra for a wiring solder joint.
Whether its the same or similar to that used on bow strings, I have no idea, but it wouldn't surprise me if they come from a similar source.
Regards
Tony.

https://www.eevblog.com/forum/chat/viol ... lder-flux/

Alan Turner
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Re: Tortoise 16v AC circuit problems

Postby Alan Turner » Mon Mar 13, 2023 4:13 pm

Julian Roberts wrote:
Alan the photo from last night is not how I set it all up this morning for your test. I did follow your instructions except I didn't do any more soldering to the microswitch terminals, rather, I re-arranged the wires into another terminal block to follow the routes as you described. TBH I thought you might be steering me to see that I'd wired this wrongly (parallel/series?).

.


Look at this: https://www.youtube.com/watch?v=h3cjSiQ ... =32&t=856s

ignore the LEDs.

see if helps.

regards

Alan

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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Mon Mar 13, 2023 4:15 pm

Thanks Will. We learn something new every day.
Regards
Tony.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 13, 2023 4:49 pm

Just watched that video first. If you go to 1 minute or a bit beyond in he demonstrates the toggle switch in use. Listen carefully exactly the same thing happens as we've been talking about here.

I was just talking to one of the "experts" mentioned yesterday, who pointed out that, supposing there are the eventual 9 motors, seldom if ever are they all going to be at the Normal position. Assuming they are all wired the same way, only the next throw will be at what I've called the "proper" speed. Most times a point is thrown it'll run at the half speed - so the discrepancy will be almost un-noticeable; the "proper" speed will seem abnormal. Not that it matters what it sounds like or how fast it travels. He suggested that unless anything is running hot, which it isn't, there isn't a problem and I should forget it! Which prompts me to wonder if what I'm questioning is something that is normal for most people? The guy in the video doesn't bat an eyelid at the different sounds.



I.e is this all a fuss about nothing!!??

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 13, 2023 5:42 pm

I've tried the quenching resistor idea Martin. When both motors are wired up to the diodes it does indeed make that motor (the one with the resistor attached) work the same speed both ways - but at about half the previous lower speed! I'll attach a video when I can.



Thanks Will by the way :D
Last edited by Julian Roberts on Mon Mar 13, 2023 5:54 pm, edited 1 time in total.

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grovenor-2685
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Mon Mar 13, 2023 5:54 pm

Julian Roberts wrote:I.e is this all a fuss about nothing!!??

Yes, I would say its a fuss about nothing. Probably one of the perils of being a musician. :)

Just had another play with my test rig, Listening and looking carefully I can see some variation in speeds similar to your reports, I would say about a 20% variation but then I'm not a musician.

At least you have learned something about meters.
Your measurements showing an increase in voltage when the motor is running agrees with my observations also.
Regards
Keith
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 13, 2023 7:28 pm

:D should I laugh or cry...spent best part of a week on this! And wasted all your time if that's right!

Laugh I think. No idea what this is about even though I played in it in the pit scores of times


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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 13, 2023 9:01 pm

Joking aside, I do apologise if I've wasted the time of you such helpful people. Going back a week or so, I think I learned in conversation that the concern would be, what happens with all nine turnout motors: four work fine, but each progressive throw makes the movement slower. So I've just rigged up the extra two motors and four from the frame, here is the video that shows less and less difference in sound and speed, so the 6th one while slow is not markedly slower than the fourth. I've made Turnout 3 the first and last to be thrown as that one is nearest the frame and camera. Apologies there's an awful lot of noise from simply moving my arms!



What I really need is for the Daves B and H to take a similar video of their installations but that is likely an ask too far! - or some report as to whether the sound or speed there has similarities. And of course I wonder what people think about this, other than Keith? Should I carry on the investigation that you Dave B were suggesting?

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Mon Mar 13, 2023 11:28 pm

Hi Julian,

You haven't wasted my time. It was/is an interesting conundrum. :)

I still think using half-wave for these motors is a kludge, and that almost certainly on a proper smoothed triple-rail DC supply they would run faster and without speed variations.

But if you are happy with the results of the kludge, it is obviously a cheap and cheerful way to go with a simple AC power source.

Applying half-wave to stalled motor coils is bound to produce some interesting voltage effects, but exactly what they are and the effect on the circuit would need some deeper investigation.

cheers,

Martin.
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Alan Turner
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Re: Tortoise 16v AC circuit problems

Postby Alan Turner » Tue Mar 14, 2023 8:28 am

Martin Wynne wrote:Hi Julian,

You haven't wasted my time. It was/is an interesting conundrum. :)

I still think using half-wave for these motors is a kludge, and that almost certainly on a proper smoothed triple-rail DC supply they would run faster and without speed variations.

But if you are happy with the results of the kludge, it is obviously a cheap and cheerful way to go with a simple AC power source.

Applying half-wave to stalled motor coils is bound to produce some interesting voltage effects, but exactly what they are and the effect on the circuit would need some deeper investigation.

cheers,

Martin.


If you want to use DC but still use SPDT switches (which the use of microswitches requires) you could use this control board:


Photo 6.JPG


It requires a positive lead (BLACK) and two ground wires (WHITE). You switch between the ground wires to control the motor. The two RED wires go to the motor.

regards

Alan
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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Tue Mar 14, 2023 9:25 am

Alan Turner wrote:If you want to use DC but still use SPDT switches (which the use of microswitches requires) you could use this control board

Hi Alan,

That looks expensive if you need one of those for every motor?

Cheaper to have a proper triple-rail supply, which needs only single-pole change-over (SPDT) switches:

tortoise_supply.png

The two 12vDC supplies must be entirely separate*. The GND wire can be your layout's common-return wire if you have one (saves on wire).

The switch must be a quality break-before-make switch (some slide-switches and rotary wafer switches are not).

(*they could be from isolated transformer secondaries/rectifiers, but if you know what that means you won't be reading this.)

cheers,

Martin.
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davebradwell
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Re: Tortoise 16v AC circuit problems

Postby davebradwell » Tue Mar 14, 2023 9:38 am

There's nothing fundamentally wrong with using half-wave power - it does, after all, make the motors go round. The problems start when trying to measure voltages with a meter not suitable for this situation and drawing rash conclusions. It's usual to fit the capacitors and mine will be either 2200 or 4700 microfarad. This gives the dc you are after (and can measure) and gets rid of the hum that surrounds a load of stalled motors.

Having said that, it's probably easier these days to buy 2 pug-in dc power supplies (as Martin has just added) and use these. Some are adjustable so the Tortoise whine can be turned down. Spares readily available in case of failure, too.

You are right, Julian, that on a practical installation the parked motors will be spread across both sides of the supply so the effect you see will not occur. I was serious about dumping the contaminated components, especially as you intend exhibiting the layout and reliability is very important. You should also look carefully at any layout wiring done with the acid flux - it's claimed it can be neutralised to prevent future corrosion so perhaps it can.

I still think it's worth measuring the resistance across several of your soldered joints in case we missed something. Sounds like it will be fine but it's still not clear why the volts come down enough to affect the motor. Probably just internal impedance but capacitors may help.

DaveB

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Tue Mar 14, 2023 10:47 am

Just for reference, the 3 alternative wirings, from the Tortoise instructions. (Ignore my writing 'orange' obviously)
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Tue Mar 14, 2023 11:28 am

Martin Wynne wrote:The two 12vDC supplies must be entirely separate*.

Not just seperate but also the outputs must be fully isolated from the inputs which essentially requires that the units must have only 2 pins, no earth pin. Power supply units with an earth pin commonly have the 0v (-ve) of the output earthed and connecting them in this way will cause a short.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Tue Mar 14, 2023 11:42 am

Thanks, I'm glad if this isn't regarded as a media storm in a teacup!

I'm guessing the varying amounts of time it takes motors to move is the demonstration of the "kludge". The points all move at the same speed on the layout I mentioned where the turnouts are operated by a relay (somehow.)

Just been making some videos while I've got the six motors wired up together (obviously with lots of unsatisfactory aspects like 145 soldered wire end strands etc.)

The first here shows the maximum difference in speed - all points normal, I reverse one (quick) and then put it back to normal (slow). That slow speed is roughly equivalent to when I had it singly operated by the Duracell 9V battery I've been using several months. Your volume will need to be on maximum probably.



Next the same turnout pulled off and returned, while 3 other turnouts are already pulled off. So here the speed is roughly the same both ways and would be a typical way it behaves in normal operation where some were normal and some reversed.



Now to some videos of the meter on 50V DC, to see how the needle behaves even if you're not seeing the actual readings clearly. The black probe is on yellow, red on grey for both of them.

First, here all six turnouts are thrown in turn, and then thrown back again. The last to be thrown is at 23 seconds.



Next, a single turnout is thrown and then returned - all others are at normal. This is as in the first video above



Is this interesting to anyone and shall I do the same on some other combinations of the yellow/grey/ orange wires?

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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Tue Mar 14, 2023 11:56 am

This is with 3 turnouts reversed already, pull one off and return it


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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Tue Mar 14, 2023 12:38 pm

grovenor-2685 wrote:
Martin Wynne wrote:The two 12vDC supplies must be entirely separate*.

Not just seperate but also the outputs must be fully isolated from the inputs which essentially requires that the units must have only 2 pins, no earth pin. Power supply units with an earth pin commonly have the 0v (-ve) of the output earthed and connecting them in this way will cause a short.

? ? ?

I have just had a rummage through my box of power adaptors, and I can't find a single one with a metal earth pin.

500ma, good for about a dozen motors (2 needed): https://uk.rs-online.com/web/p/ac-dc-adapters/1753294

2.5A, for large layouts (2 needed): https://uk.rs-online.com/web/p/ac-dc-adapters/2008939

cheers,

Martin.
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Tony Wilkins
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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Tue Mar 14, 2023 2:06 pm

Post deleted. See below.
Regards
Tony.
Last edited by Tony Wilkins on Wed Mar 15, 2023 11:11 am, edited 2 times in total.
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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Tue Mar 14, 2023 2:37 pm

Julian Roberts wrote:
I'm guessing the varying amounts of time it takes motors to move is the demonstration of the "kludge". The points all move at the same speed on the layout I mentioned where the turnouts are operated by a relay (somehow.)


Hi Julian.
The relay simply does the same thing as the microswitch, but remotely. There may also be a difference in the design of the power supply. In my case I have used a fully rectified and smoothed 9V transformer output. This produces 14 volts DC with no load.
As already mentioned, I am using Cobalt motors. The instructions state average power 20mA when they really mean current. However their internal resistance is somewhat lower than a Tortoise at about 140ohms meaning that when stalled they will draw about 100mA or 0.1A. They do include a switch for higher supply voltages and this increases their stall resistance to about 330ohms and reduces the stall current to 43mA drain This soon mounts up though and with some 80 point motors installed could amount to a current drain approaching 3.5 A. In practice it doesn't quite work out like that as when the load increases the supply voltage falls to about 12V, so reducing the current drain a bit. It has meant that I have had to arrange the point motor supply in such a way that with all the turnouts normal half are supplied from the positive rail and half from the negative rail.
In these energy conscious times it seems rather perverse to be wasting close to 50 watts all the time the layout is powered up, but that is the consequence of the situation.
Regards
Tony.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Tue Mar 14, 2023 6:48 pm

Tony Wilkins wrote:A cheaper option is to add two further diodes to the circuit to form a bridge rectifier.
Tortoise mod.JPG
This will give you full wave rectification and a higher output voltage although unsmoothed.
Regards
Tony.


Hi Tony - thanks for this.
If this works better I wonder why it's not on the Tortoise instructions? Annoyingly I've mislaid two of the four diodes Nigel sent me of 1A, so I've got two at 3A and two at 1A - would it be inadvisable to try the circuit with those four? If so I've got to make an order for various supplies so I'll get some soon.

Alan thanks for the reference to that accessory which I'd seen promoted. Re the following diagram from Martin, I'm going to see if this AC above circuit works and may stick with this "kludge" in any case ;)

davebradwell wrote:
I can't see that your readings on ac tell us anything. What we want are the dc voltages across the motor under the different conditions to support my initial assertion. Before that you might measure the resistance from one diode terminal through the 3 soldered joints and closed microswitch to the Tortoise terminal. It should, of course, match your zero setting exactly.


DaveB


Dave, do the meter videos I put here this morning show what you meant? Fraid I need clearer instruction what to measure the resistance of if that's still of interest. There was only one soldered joint between diodes which is now eliminated by extra loops of wire between terminals on the choc bloc.

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Tue Mar 14, 2023 8:16 pm

Julian Roberts wrote:If this works better I wonder why it's not on the Tortoise instructions?

Hi Julian,

I'm struggling to see how that circuit can work. Current doesn't usually go round in circles. Tony?

But worth a try if you have some spare diodes. The current ratings don't matter for a trial if you have 4 diodes to hand.

cheers,

Martin.
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Tue Mar 14, 2023 9:34 pm

Right, Martin, thank you, but I'll wait for Tony to reply to your question!

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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Tue Mar 14, 2023 10:15 pm

Tony Wilkins wrote:A cheaper option is to add two further diodes to the circuit to form a bridge rectifier.
Tortoise mod.JPG
This will give you full wave rectification and a higher output voltage although unsmoothed.
Regards
Tony.

IMHO, if you follow the current paths the motor is still getting only half wave as there is no return path for the other half. The two extra diodes are smoke and mirrors.
Regards
Keith
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