ECM Compspeed controller on pure DC?

[tebee]

I'm doing a retro layout which needs DC control. I've got a number ECM Compspeed controllers lying about which I could use, but it would appear that all the old transformers I have stashed away no longer work !

 

Would they work with a modern power brick that gives smoothed DC or do they specifically need an AC supply ? The power bricks seem significantly  cheaper than buying a cased transformer. 

 

I can't find any details of the circuit the compspeed uses to try and work it out myself.

[brigo]

The ECM Compspeed needs an AC input. The output is a series of pulses whose timing is derived from the 50 Hz AC The compspeed was discussed fairly recently.

 

.http://www.rmweb.co.uk/community/index.php?/topic/133793-ecm-compspeed-circuit/

 

Sketch of the circuit for the standard Mk 1 Compspeed

 

 

Brian

[Pete the Elaner]

Open transformers don't cost much. I bought a couple from www.rapidonline.com recently for about £8 each.

You'll need to mount them, typically in a control panel or under the board then you will probably want to cover with some bits of wood or plasticard for safety.

[Colin_McLeod]

Be very careful regarding making this safe. 240v can kill and the open transformer should be enclosed in a suitable box and not just "covered with some bits of wood or plasticard"

[dhjgreen]

Be very careful regarding making this safe. 240v can kill and the open transformer should be enclosed in a suitable box and not just "covered with some bits of wood or plasticard"

Also fuses on the primary and secondary sides and the frame of the transformer earthed. I would not go there.

Edited December 17, 2018 by dhjgreen

[hayfield]

I'm doing a retro layout which needs DC control. I've got a number ECM Compspeed controllers lying about which I could use, but it would appear that all the old transformers I have stashed away no longer work !

 

Would they work with a modern power brick that gives smoothed DC or do they specifically need an AC supply ? The power bricks seem significantly  cheaper than buying a cased transformer. 

 

I can't find any details of the circuit the compspeed uses to try and work it out myself.

 

I recently bought 3 transformers at a local show, one a mains controller the other two needing 16v input. The mains controller has a 16v AC output. Paid £5 (they asked 50p each so I told them to add the change to the club funds) thinking I would have a good deal if only 1 worked, all 3 are fine !!

 

Just go to these small type of shows look on both the traders and club sale stands for bargains or your local model railway shop if it sells sh items. Those sold by traders should be PAC tested

[tebee]

Open transformers don't cost much. I bought a couple from www.rapidonline.com recently for about £8 each.

You'll need to mount them, typically in a control panel or under the board then you will probably want to cover with some bits of wood or plasticard for safety.

 

 

Be very careful regarding making this safe. 240v can kill and the open transformer should be enclosed in a suitable box and not just "covered with some bits of wood or plasticard"

 

 

Also fuses on the primary and secondary sides and the frame of the transformer earthed. I would not go there.

 

 

This is precisely why I'd have prefered to buy one of the  switched mode power supplies from China - they're cheap  - I just paid £3.95 for a 6 amp 12v one for my kitchen lights inc postage - and they come ready in a nice package. They are also more efficient than an old style transformer. They are easier to get - I live out in the wilds of rural France, buying large components either entails a 200km round trip or paying the price of the item again in postal charges.

 

But I had a vague memory that they needed either unsmoothed DC or AC input, so it looks like I was right.

[kevinlms]

This is precisely why I'd have prefered to buy one of the  switched mode power supplies from China - they're cheap  - I just paid £3.95 for a 6 amp 12v one for my kitchen lights inc postage - and they come ready in a nice package. They are also more efficient than an old style transformer. They are easier to get - I live out in the wilds of rural France, buying large components either entails a 200km round trip or paying the price of the item again in postal charges.

 

But I had a vague memory that they needed either unsmoothed DC or AC input, so it looks like I was right.

Agreed, because even experts can get it wrong. At my club we had a member build a power supply with all the trimmings, including a safety switch built in.

When I tested it a couple of years later, I found that the active and neutral were reversed! He was horrified when I discretely told him. He had years of experience, working on specialised equipment, including military radar and calibrating specialised test equipment. Naturally he was highly embarrassed to make a beginners mistake, especially when the the equipment had been in service for some time.

[Pete the Elaner]

Be very careful regarding making this safe. 240v can kill and the open transformer should be enclosed in a suitable box and not just "covered with some bits of wood or plasticard"

Oops. I did describe that a bit sloppily, but I did actually mean to build a suitable box.

You didn't even need to twist my words or 'selectively' drop some key ones either. 

[hayfield]

Oops. I did describe that a bit sloppily, but I did actually mean to build a suitable box.

You didn't even need to twist my words or 'selectively' drop some key ones either. 

 

Pete

 

The trouble is there are some who would take you seriously and at face value. Unless someone is profficent (better still qualified) electrician its much better for those like me buying a pre-built unit.

 

May even be worth keeping it separate from the baseboard/control panel, on the basis that the mains supply is safely away from where fingers may go 

[sharris]

Oops. I did describe that a bit sloppily, but I did actually mean to build a suitable box.

You didn't even need to twist my words or 'selectively' drop some key ones either. 

 

I wouldn't even build a box - there are plenty (by which I mean 1000s) to choose from from RS, Farnell, etc. ready made that would just need cutouts made for the mains inlet and low voltage output terminals. 

[brigo]

As the OP lives in France, could I suggest looking on eBay or locally for people selling off the transformers from train sets. The train sets from Roco,Trix, etc normally contain a conventional transformer in a plastic case either as a wallplug mounted or on a short cable. Many people often buy the sets because they are a cheap way of buying a particular loco (I have done so) and then selling the controller and track off. This also applies to DCC sets which contain a decent transformer.

 

Brian

[boxbrownie]

Make sure it is the transformers you have which are the problem, I had a few Compspeeds some years ago and I had them stored for a while, when I got them out each one had problems moving anything on the track and one was completely dead, I assume a component inside had a finite life!

[brigo]

Make sure it is the transformers you have which are the problem, I had a few Compspeeds some years ago and I had them stored for a while, when I got them out each one had problems moving anything on the track and one was completely dead, I assume a component inside had a finite life!

 

Electrical components can deteriorate over the years, but it will mainly be switches or potentiometers where the contacts can get an oxide coating or just plain grime. Electrolytic capacitors can also dry out and fail.

 

Brian

[doilum]

Back in the day ECM sold a suitable transformer ( TR6 ???). Many people just screwed them to the underside of the layout. I was considered a bit of a wuss for putting mine in box. This was the heavy steel case from my original Triang transformer. It is still giving good service.

For those choosing to remain analogue, the Compspeeds are in my humble opinion, one of the best controllers ever made.

[boxbrownie]

Electrical components can deteriorate over the years, but it will mainly be switches or potentiometers where the contacts can get an oxide coating or just plain grime. Electrolytic capacitors can also dry out and fail.

 

Brian

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

[tebee]

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

 

Annoying all my old H&Ms seem to have packed up. I bought a £5 Flyer from a club stand last time I was in the UK for use on my test track and that died 2 days ago. Worst was a brand new in the box Executive which failed to work when I plugged it is - though it had been in that box for over 20 years ...

[Crosland]

If you are worried about safety, or competence, in using a transformer, then Gaugemaster will sell you something like this http://www.gaugemaster.com/item_details.asp?code=GMC-M1&style=main&strType=&Mcode=Gaugemaster+GMC-M1 for over £50, or, save a good few quid and just buy an AC "wall wart" or "power brick"  https://uk.farnell.com/c/power-line-protection/power-supplies/ac-ac-external-plug-in-adaptor-power-supplies 

[tebee]

If you are worried about safety, or competence, in using a transformer, then Gaugemaster will sell you something like this http://www.gaugemaster.com/item_details.asp?code=GMC-M1&style=main&strType=&Mcode=Gaugemaster+GMC-M1 for over £50, or, save a good few quid and just buy an AC "wall wart" or "power brick"  https://uk.farnell.com/c/power-line-protection/power-supplies/ac-ac-external-plug-in-adaptor-power-supplies 

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.

[kevinlms]

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

Out of curiosity, do you know the type of resistance mat contained within it? I have an old H&M catalogue and it states that all units were fitted with medium or 40 ohm resistance mats at the works. Available to order or replacement within 7 days, were 6 different resistances - 80, 60, 40, 30, 20 and 10 ohms.

 

Perhaps this is why some users, state that they are very satisfied with their Duette performance and others hate them.

 

I will post a scan of the relevant page in the next day or so.

[kevinlms]

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.

Not so, you can certainly buy AC output versions. This is an Australian version, but they are generally available, worldwide.

 

https://www.jaycar.com.au/16v-ac-1-25-amp-alarm-power-supply/p/MP3021

[sharris]

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.

 

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

[tebee]

But 

 

Not so, you can certainly buy AC output versions. This is an Australian version, but they are generally available, worldwide.

 

https://www.jaycar.com.au/16v-ac-1-25-amp-alarm-power-supply/p/MP3021

 

 

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

 

But both those to are £20+ for a 12v 1 amp+ power supply and quite a few of the options are no longer manufactured. I'd probably save money by looking for a cheap consumer item that used them and buying that !  No 15/16v ac ones seem available now for instance. 

 

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

[boxbrownie]

Annoying all my old H&Ms seem to have packed up. I bought a £5 Flyer from a club stand last time I was in the UK for use on my test track and that died 2 days ago. Worst was a brand new in the box Executive which failed to work when I plugged it is - though it had been in that box for over 20 years ...

No idea, but it does have a two setting resistance switch on the front as well as half wave switch.

[tebee]

Well I pulled the H&M Flyer appart. The problem turned out to be the diode bridge gone short circuit - it's made up of discrete diodes, rather small ones. Disconnected it for the moment so I can use the AC output to test the compspeeds.

 

Both the normal single knob ones worked, but only 1 of the 2 Rambler Minors did.

 

Will search out other failed transformer controllers I have and see if any others will work as AC supplies only, as I'd like to fix the Flyer for using on my test track again.

 

Another suggestion from another forum is the power supply for halogen lamps. I may have some of these already, as the railway in the basement of my old house was lit by these. Brought them with me with the intention of using these on my new garage line, but by the time I'd got round to building this cheap LED stips had become avalabile and I've used those instead.