Tortoise 16v AC circuit problems

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grovenor-2685
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Fri Mar 17, 2023 1:44 pm

grovenor-2685 wrote:
Julian Roberts wrote:Despite Martin's warning I did try the pair of larger capacitors (the right way round) on the circuit of two motors - the effect was quite dramatic, the motor threw at an alarmingly fast speed - but the good news is that the return throw seemed to be the same speed (I wasn't going to investigate by repeating the process for fear of damaging the motor). Nigel (who is out of the country just now) when sending them to me suggested just one small one might do the trick but wasn't clear which one in the diagram that would be.
If you use capacitors then they will charge up to the peak voltage, likely around 20V, the size won't make much difference (unless really very small). Tortoises are usually to fast at 12V, best at about 9V which is why the half wave circuit is quite good for them. If you use capacitors it has to be two, just using one will give the motors a smooth 20V in one direction and leave them with the half wave 10V in the other. I doubt he meant that.
He sent this diagram in case it was needed

You can add more diodes like that to reduce the voltage, each diode in the chain dropping about 0.7V, so to drop from 20V to 10V you would need a chain of 14 diodes! IMHO accept the speed variations or can the half wave system and get two small PSUs, ideally 9V ones as as has been suggested.
Regarding flux etc, Noel thanks for your answer too, here are the options from one place. I've found that solder tags, microswitch terminals, etc, take the solder very easily, acting as though they are already tinned - is that likely? I assume that a tin of "Fluxite" isn't what I should be after.
Definitely not fluxite. Usually component leads, solder tags etc. are pre tinned, microswitches not always as some are intended for push on connectors. But clean copper will solder well with cored solder, no need of extra flux.
Regarding electrical solder I have got one of those packets of Carrs that contain sufficient for someone of a more anorexic approach than mine. None of these say "electrical"
In an earlier post you did say you had used electrical solder, was that the Carrs? I didn't think he did any cored solder.
For any electrical wiring I would recommend old fashioned lead 60%/tin 40% solder with rosin flux core. eg. https://cpc.farnell.com/duratool/d01681/solder-wire-sn60-pb40-0-7mm-100g/dp/SD01535?st=60/40%20100gh

Don't go for 'lead free' it gives lots of trouble. Only that first item on your link looked to be proper 60/40.
Regards
Keith
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Tony Wilkins
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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Fri Mar 17, 2023 2:06 pm

I was out most of yesterday and catching up with this topic. I have used 25V Electrolytic capacitors in my power supplies and none have blow up so far. Rectified and smoothed 16V AC should give about 22.5 V DC and the diodes will reduce this a bit further.
Most of what I would have commented on has been covered already.
However while at my club yesterday I recovered the control panel that came with our acquired layout as I wanted to take a picture as a warning of what happens when using acid flux for electrical work. Click on the image twice to see the full horror story.
Control panel rear.jpg

This panel will be replaced and is only being used for test purposes.
Proof that the acid is still about comes from the smell arising when resoldering poor joints with proper electrical solder. It smells like phosphoric acid.
Regards
Tony.
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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 17, 2023 2:32 pm

grovenor-2685 wrote:If you use capacitors then they will charge up to the peak voltage, likely around 20V

Hi Keith,

Given the likely poor regulation of the 16vac supply, it is probably around 19v rms on open-circuit, which means the peak would be 26.9v. A small dummy load such as a 4.7K resistor will bring that down when there is no motor load, and the diodes will drop a volt too, but it's still too close for comfort to the 25v rating of the capacitor.

I don't know how a load on one half of the wave affects the peak on the other unloaded half -- it might actually increase it. Julian posted an image of his meter showing 30v, which must have come from somewhere.

cheers,

Martin.
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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Fri Mar 17, 2023 2:40 pm

grovenor-2685 wrote:For any electrical wiring I would recommend old fashioned lead 60%/tin 40% solder with rosin flux core. eg. https://cpc.farnell.com/duratool/d01681/solder-wire-sn60-pb40-0-7mm-100g/dp/SD01535?st=60/40%20100gh
Don't go for 'lead free' it gives lots of trouble. Only that first item on your link looked to be proper 60/40.

I would agree whole wholeheartedly with Keith on that. There is a reason that 60/40 Tin Lead solder was used. It was what was found to work best for electrical work.
Regards
Tony.
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Alan Turner
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Re: Tortoise 16v AC circuit problems

Postby Alan Turner » Fri Mar 17, 2023 3:00 pm

Julian Roberts wrote:Hi Alan - you didn't put in a link for the control board in your post yesterday


https://merg.org.uk/merg_wiki/doku.php? ... b_to_drive

You have to be a member of MERG though.

regards

Alan

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Re: Tortoise 16v AC circuit problems

Postby Alan Turner » Fri Mar 17, 2023 3:01 pm

Tony Wilkins wrote:
grovenor-2685 wrote:For any electrical wiring I would recommend old fashioned lead 60%/tin 40% solder with rosin flux core. eg. https://cpc.farnell.com/duratool/d01681/solder-wire-sn60-pb40-0-7mm-100g/dp/SD01535?st=60/40%20100gh
Don't go for 'lead free' it gives lots of trouble. Only that first item on your link looked to be proper 60/40.

I would agree whole wholeheartedly with Keith on that. There is a reason that 60/40 Tin Lead solder was used. It was what was found to work best for electrical work.
Regards
Tony.


And remember Lead free solder is not allowed in aerospace applications - there is a reason for that!

regards

Alan

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Martin Wynne
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Re: Tortoise 16v AC circuit problems

Postby Martin Wynne » Fri Mar 17, 2023 3:09 pm

Tony Wilkins wrote:There is a reason that 60/40 Tin Lead solder was used. It was what was found to work best for electrical work.


Hi Tony,

63/37 Tin/Lead is better if you can get it. It's a eutectic alloy which means it stays bright, with no slushy phase on cooling, so much less risk of dry joints. Adding 2% silver to make 62/36/2 is even better, with improved wetting and flow (i.e. "179°C solder" from model suppliers). More info:

https://fctsolder.com/eutectic-solder

From which: "Non-eutectic 60/40 solder melts in the range of 183 to 191 °C. As this alloy is heated it starts to melt at 183°C, is slushy between 183°C and 191°C, and becomes fully liquid at 191°C.
Eutectic solders tend to have a bright, shiny appearance while non-eutectic solders tend to have a dull, grainy appearance."


cheers,

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

Postby Julian Roberts » Fri Mar 17, 2023 8:57 pm

Again, very many thanks Tony, Martin and Keith* for making the time to give all this very useful information. For now I'm happy with the turnout operation and won't do any more experiments as time is limited. Jim - the decision to go with Tortoises was in full knowledge of the reported problems with the changeover switches (and the Andrew Jukes thread), as against the many reports like yours. Dave, your remedy sounds drastic but it's useful to know if problems arise in future that there may be a solution, and there's the option of using a relay instead. Keith, the Carr's solder is called Speedy Solder; it is cored and claims to have good electrical soldering properties. But I'll get the proper stuff now I know what.

*And Dave

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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Sat Mar 18, 2023 1:00 pm

Martin Wynne wrote:
Tony Wilkins wrote:There is a reason that 60/40 Tin Lead solder was used. It was what was found to work best for electrical work.


Hi Tony,

63/37 Tin/Lead is better if you can get it. It's a eutectic alloy which means it stays bright, with no slushy phase on cooling, so much less risk of dry joints. Adding 2% silver to make 62/36/2 is even better, with improved wetting and flow (i.e. "179°C solder" from model suppliers). More info:

https://fctsolder.com/eutectic-solder

From which: "Non-eutectic 60/40 solder melts in the range of 183 to 191°C. As this alloy is heated it starts to melt at 183°C, is slushy between 183°C and 191°C, and becomes fully liquid at 191°C.
Eutectic solders tend to have a bright, shiny appearance while non-eutectic solders tend to have a dull, grainy appearance."


cheers,

Martin.

Hi Martin.
Thanks for the info, but I already have a stockpile of 60/40 solder (188°C) as when it was announced that it was to be phased out in favour of lead free solder, I made sure I acquired a load, but that's another story that I won't go into here.
Regards
Tony.
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Sun Mar 19, 2023 8:34 pm

Tony Wilkins wrote:However while at my club yesterday I recovered the control panel that came with our acquired layout as I wanted to take a picture as a warning of what happens when using acid flux for electrical work. Click on the image twice to see the full horror story.
Control panel rear.jpg
This panel will be replaced and is only being used for test purposes.
Proof that the acid is still about comes from the smell arising when resoldering poor joints with proper electrical solder. It smells like phosphoric acid.
Regards
Tony.


Hi Tony

Somehow I missed this post till more recently. Thanks for this warning. I think somewhere I had read on this Forum that a slosh of methylated spirits over the soldered joints of a model being built using 145 and phosphoric acid would wash off the acid. I brushed this over solder tags etc under this layout I'm making. Obviously I will now mend my ways and use the proper procedures but I wonder if this might have forestalled the worst? I seem to remember Ricey saying in one of his books that a slosh with (or in) water and dilute Washing Soda would achieve the same objective.

Regarding the solder that's been recommended, the RS online site says it is only available for professional use. When registering it asks for my occupation - "other" is the only category I properly belong to, or "hobbyist": I wonder whether ticking those boxes will prevent me from ordering this solder, does anyone know?

Regarding further progress on installing capacitors, resistors, more diodes, etc, I'm just putting that to one side till I get to meet up with some of the clever people near here. Having established that there is no actual fault I'm quite happy with the operation for now.

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grovenor-2685
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Sun Mar 19, 2023 10:07 pm

Julian Roberts wrote:Regarding the solder that's been recommended, the RS online site says it is only available for professional use. When registering it asks for my occupation - "other" is the only category I properly belong to, or "hobbyist": I wonder whether ticking those boxes will prevent me from ordering this solder, does anyone know?

Which is why I gave you the link to CPC, I am reasonably sure they have no such restriction, I purchased a reel recently. https://cpc.farnell.com/duratool/d01681/solder-wire-sn60-pb40-0-7mm-100g/dp/SD01535?st=60/40%20100gh
PS. I linked to a 100g reel, given the handling charge you get a better rate if you go for larger, eg 500g.
Regards
Keith
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Julian Roberts
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Re: Tortoise 16v AC circuit problems

Postby Julian Roberts » Mon Mar 20, 2023 11:01 am

Thanks Keith - actually the CPC site says the same thing. Talking on the phone to them, she said I can just order it anyway - I'll say here if that proves to be any problem.

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Re: Tortoise 16v AC circuit problems

Postby Tony Wilkins » Mon Mar 20, 2023 11:26 am

Also available from some traders at model railway shows.
Regards
Tony.
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Re: Tortoise 16v AC circuit problems

Postby grovenor-2685 » Mon Mar 20, 2023 1:57 pm

Julian Roberts wrote:Thanks Keith - actually the CPC site says the same thing. Talking on the phone to them, she said I can just order it anyway - I'll say here if that proves to be any problem.

It gives a warning sure, but no restriction on actually buying it.
Unlike RS who specifically say they cannot supply the general public.
Regards
Keith
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Winander
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Re: Tortoise 16v AC circuit problems

Postby Winander » Mon Mar 20, 2023 2:31 pm

grovenor-2685 wrote:Unlike RS who specifically say they cannot supply the general public.

And only limited companies count as professionals, for sole traders they say 'no'.
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Re: Tortoise 16v AC circuit problems

Postby Alan Turner » Mon Mar 20, 2023 4:00 pm

Winander wrote:
grovenor-2685 wrote:Unlike RS who specifically say they cannot supply the general public.

And only limited companies count as professionals, for sole traders they say 'no'.


Not so. I buy my solder from RS.

regards

Alan

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Re: Tortoise 16v AC circuit problems

Postby Winander » Mon Mar 20, 2023 5:35 pm

Alan Turner wrote:
Winander wrote:
grovenor-2685 wrote:Unlike RS who specifically say they cannot supply the general public.

And only limited companies count as professionals, for sole traders they say 'no'.


Not so. I buy my solder from RS.

They refused to supply me in 2021 stating only a Ltd co was acceptable.
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