ECM Compspeed controller on pure DC?

[Crosland]

The problem is most of the wall warts and the like are high  frequency switch mode power supplies which supply smoothed DC - ideal for most situations, but not unfortunately, the Compspeeds.

 

That's why I stressed buy an AC wallwart. Perhaps I should have said AC Output but anyone who bothered to follow the links would understand.

[Crosland]

No 15/16v ac ones seem available now for instance. 

 

I give up!

[PatB]

Another potentially cheap transformer option is an old-fashioned non-smart car battery charger. I've got one and the insides are pretty simple. A big mains transformer and a bunch of chunky diodes to supply unsmoothed DC. I'm not sure what amperage it could supply but I'd expect it to be enough to weld several Dublo locos to the track simultaneously. As a bonus it's better at abusing charging dead batteries than any of the smart rubbish now available.

 

On safety, many years ago when I was a mediocre Physics student at the University of Newcastle, one of the 1st or 2nd year experiments used a 12V bulb as a light source. This was fed from a large, open transformer bolted to a plywood base. Under the base the three cores of the mains lead were soldered to droppers from the transformer primary, the bare wires and solder joints having no insulation or protection whatsoever. Even at the time I thought it was an interesting bit of kit to allow idiot 18-19 year olds to play with largely unsupervised.

[polybear]

 

Chinese 12v dc power supplies can be had for a couple of quid ! 

 

But worth bearing in mind the regular warnings about the amount of fake and positively dangerous unsafe kit for sale on ebay.....

[DCB]

These non model railway power units don't have overload protection optimised for small motors etc, always assuming they have any so be careful. You could burn down the shed or put a nasty burn mark on the living room carpet if you get it wrong.  I use 1/2 amp or 1 amp Polyswitches on the outputs if I can't find an old bi metal strip overload which works. Lots of articles mentioning overload protection in mid 1950s railway magazines.

[boxbrownie]

Even at the time I thought it was an interesting bit of kit to allow idiot 18-19 year olds to play with largely unsupervised.

Hey.....it was Uni......your on a learning curve

[kevinlms]

But worth bearing in mind the regular warnings about the amount of fake and positively dangerous unsafe kit for sale on ebay.....

Three ways of looking at this topic - the list doesn't necessarily represent my choice! They just come out this way, when typing.

 

Does it work?

Is it cheap?

Is it safe?

 

Obviously different people have different ideas, of which order is important to them!

[hayfield]

Three ways of looking at this topic - the list doesn't necessarily represent my choice! They just come out this way, when typing.

 

Does it work?

Is it cheap?

Is it safe?

 

Obviously different people have different ideas, of which order is important to them!

 

 

I would always be wary about cheap far eastern products when not bought from reputable UK/EU dealers where the items are safety tested ot CE standards. Too many instances of chargers catching fire !!!! 

[Crosland]

 CE standards. 

 

Chinese Export standard

[tebee]

Isn't CE self-certified ?

 

I know when we were looking to import something from China a few years ago the CE stamp was an optional extra, but only a couple of pence a unit extra, so I guess the CE stamped one was exactly the same as the non CE stamped one.

[kevinlms]

Isn't CE self-certified ?

 

I know when we were looking to import something from China a few years ago the CE stamp was an optional extra, but only a couple of pence a unit extra, so I guess the CE stamped one was exactly the same as the non CE stamped one.

The stamp itself costs nothing. Whether it complies or not, is another matter!

[hayfield]

Chinese Export standard

 

 

Isn't CE self-certified ?

 

I know when we were looking to import something from China a few years ago the CE stamp was an optional extra, but only a couple of pence a unit extra, so I guess the CE stamped one was exactly the same as the non CE stamped one.

 

 

The stamp itself costs nothing. Whether it complies or not, is another matter!

 

 

The point I was trying to make is that there have been many serious issues with cheap imported transformers (many with the CE stamp on and sometimes bought of the internet from UK based companies) catching fire. I now steer clear of buying anything but genuine recognised branded items or items brought from leading stores, with anything that plugs into the mains.

 

With items like transformers, building your own power source using components should only be done (or certainly checked ) by those qualified to do so, whilst in some instances buying recognised branded items should be treated as buyer beware, if in doubt either steer clear of get it tested.

 

Not being an electrician, I feel some transformers not designed for model railway use may not be up to the job anyway in their output. And certainly the power source is best kept apart from the railway board

[Crosland]

Be afraid, be very afraid

 

https://www.edn.com/design/pc-board/4441830/Teardown--12V-AC-adapters---The-Horror

[Joseph_Pestell]

The ones that Crosland linked to are specifically AC output supplies. Unfortunately a couple of hidden characters crept into the end of the URL so it ended up not found. The correct URL is... 

 

https://uk.farnell.com/c/power-line-protection/power-supplies/ac-ac-external-plug-in-adaptor-power-supplies

 

None of the ones that I can see there have enough power output (if I remember my O-level physics correctly).

[PatB]

Be afraid, be very afraid

 

https://www.edn.com/design/pc-board/4441830/Teardown--12V-AC-adapters---The-Horror

 

Looks to me as if the Chinese might be recycling some of the staggering quantities of electronic waste that get generated these days. Obtain old mains electronic devices cheap (possibly even get paid to take them away), employ a handy sweatshop to remove useful units like power supplies, and put the results in respectable looking boxes for subsequent profitable sale on Ebay, AliExpress etc. What's not to like as a business model?

[kevinlms]

The point I was trying to make is that there have been many serious issues with cheap imported transformers (many with the CE stamp on and sometimes bought of the internet from UK based companies) catching fire. I now steer clear of buying anything but genuine recognised branded items or items brought from leading stores, with anything that plugs into the mains.

 

With items like transformers, building your own power source using components should only be done (or certainly checked ) by those qualified to do so, whilst in some instances buying recognised branded items should be treated as buyer beware, if in doubt either steer clear of get it tested.

 

Not being an electrician, I feel some transformers not designed for model railway use may not be up to the job anyway in their output. And certainly the power source is best kept apart from the railway board

Not being specifically designed for model railways, ought not be a problem. After all say, 16 volts AC at 1 Amp should mean exactly that. It should be able to provide 1 Amp at 16 volts, if it drops away to say 14 volts at such a current, then it is poorly designed or is likely to be a fake.

[Colin_McLeod]

Model railway specific transformers tend to have built in safety cut outs. Do not assume this applies to every alternative transformer.

[robert17649]

I had an old Compspeed, sounds like a song!

 

When I tested it it worked ok on the correct input in this case 16v dc via an equally old H and M controller.

 

things worked reasonably but when I ran the same loco, a Dapol PUG with exactoscale EM wheelset, on my less old Gaugemaster feedback controller it was clear that the comspeeds performance was not in the same class.

 

I ran a few others , the old rewheeled B12 with the XO4 was ok on both but the others a couple of wills J67's on brass chassis showed significantly better performance on the Gaugemaster.

 

Does any one want an old Compspeed?

[Crosland]

I think we need to be clear on terminology and compare apples with apples The discussion started out with buying a bare transformer and wiring it to the mains.

 

Not being specifically designed for model railways, ought not be a problem. After all say, 16 volts AC at 1 Amp should mean exactly that. It should be able to provide 1 Amp at 16 volts, if it drops away to say 14 volts at such a current, then it is poorly designed or is likely to be a fake.

 

A transformer output is expected to drop at the rated load.

 

A power supply (e.g. transformer, rectifier, reservoir capacitors) that droops under load may not be regulated, in which case there is probably nothing wrong with it.

 

 

Model railway specific transformers tend to have built in safety cut outs. Do not assume this applies to every alternative transformer.

 

Anything with extra components is not just a transformer. Unfortunately the term has been misappropriated. This is especially the case in the US where complete power supplies are often referred to as transformers.

[34theletterbetweenB&D]

...On safety, many years ago when I was a mediocre Physics student at the University of Newcastle, one of the 1st or 2nd year experiments used a 12V bulb as a light source. This was fed from a large, open transformer bolted to a plywood base. Under the base the three cores of the mains lead were soldered to droppers from the transformer primary, the bare wires and solder joints having no insulation or protection whatsoever. Even at the time I thought it was an interesting bit of kit to allow idiot 18-19 year olds to play with largely unsupervised.

 

Just as it should be, and you are still alive to prove it, despite fiddling with the innards of mains powered equipment. I took a 5kV belt as an even more idiotic 16 year old beginning an A level physics course, Which taught me - unforgettably! - to ever after be thorough in matters relating to my own and other's safety.

 

(If I ran the country, you wouldn't be able to learn to drive a vehicle without a pass in comprehension of Newtonian mechanics.)

[boxbrownie]

 

(If I ran the country, you wouldn't be able to learn to drive a vehicle without a pass in comprehension of Newtonian mechanics.)

The most effective “safety device” in a vehicle would be a nine inch steel spike on the steering wheel boss........

[Dunsignalling]

Exactly........oddly I have a 40 year old (or more) H&M Duette which still works fine........

That pre-dates "electronics", of the sort you find in an ECM Compspeed, though.

 

Those were some of the best hand-helds/panel mounts of their time, but that was then, this is now, and you can do better. They went out of production a good while ago and even late ones will be getting on a bit now.

 

Several that we had in the group I used to attend gave up the ghost a few years ago. IIRC a couple of them were repairable, but, if you need something you can rely on, I'd replace it with something new. We went for KPC, now also out of production, though I understand somebody still makes a unit that's the same inside.

 

Even apparently bulletproof antiques from the likes of H&M that still seem as good as new can have deteriorated internally and should really be tested annually for safety's sake.

 

John

Edited December 22, 2018 by Dunsignalling

[kevinlms]

 

 

Not being specifically designed for model railways, ought not be a problem. After all say, 16 volts AC at 1 Amp should mean exactly that. It should be able to provide 1 Amp at 16 volts, if it drops away to say 14 volts at such a current, then it is poorly designed or is likely to be a fake.

 

A transformer output is expected to drop at the rated load.

 

 

 

Exactly so, that is why my example showed something outside its specified ratings.

Edited December 22, 2018 by kevinlms

[Colin_McLeod]

Model railway specific transformers tend to have built in safety cut outs. Do not assume this applies to every alternative transformer.

  

 

Anything with extra components is not just a transformer. Unfortunately the term has been misappropriated. This is especially the case in the US where complete power supplies are often referred to as transformers.

 

Perhaps I should have referred to a model railway power unit

[sharris]

That pre-dates "electronics", of the sort you find in an ECM Compspeed, though.

 

Looking at the sketch on page 1 of this thread of the circuit diagram there is, however, nothing that didn't exist (just) 50 years ago - 4000 series CMOS was introduced in 1968, the commercial release of 7400 series TTL a little earlier, and 1968 was when a process was created to make LEDs affordable, so theoretically a 50 year old ECM Compspeed would have just about been possible, although with just introduced components probably rather expensive. Edited December 23, 2018 by sharris