I have an old but unused rectifier transformer made by RS. I am not sure which terminals to wire to and I don't want to damage it. Its terminals are marked (primary) SCN, 245, 225, 205 and 0V. The secondary are 20, 12, 0, 12, 20V all left to right. It's maximum load is 0.7A. D.C. I would like to get the 20 volts out of it and use it to run a speed controller. It would be nice however if I could have a bit of support to ensure I wire it up correctly. Can anyone help please?
primary
N to 0V
Live to 245
secondary
0V to 0V
positive to 20V
if the voltage out is a little low, move the live to the 225 tapping.
by the description of the terminals, it sounds like a transformer with no rectifier so the output may well be AC
N to 0V
Live to 245
secondary
0V to 0V
positive to 20V
if the voltage out is a little low, move the live to the 225 tapping.
by the description of the terminals, it sounds like a transformer with no rectifier so the output may well be AC
Thanks for the reply it is much appreciated. It is defiantly a rectifier transformer, it says so on the coil insulation and the box plus it states its maximum output is 0.7v D.C.
My question is which terminals do I connect to on the primary side. I think it is the 0V one and the 225 volt (assuming our mains is 220Volt). However I want to be sure.
Also on the primary side terminals there is one marked SCN. I presume that means secondary but what does it do and if it is a secondary terminal why is it with the primary terminals. Once I do connect it I can meter the secondary terminals to see what comes out of it, all quite exciting really.
As my intended use is a speed control for a model railway the actual voltage output is not critical, just needs to be somewhat greater than the usual Hornby 12volt for a somewhat thirst motor.
My question is which terminals do I connect to on the primary side. I think it is the 0V one and the 225 volt (assuming our mains is 220Volt). However I want to be sure.
Also on the primary side terminals there is one marked SCN. I presume that means secondary but what does it do and if it is a secondary terminal why is it with the primary terminals. Once I do connect it I can meter the secondary terminals to see what comes out of it, all quite exciting really.
As my intended use is a speed control for a model railway the actual voltage output is not critical, just needs to be somewhat greater than the usual Hornby 12volt for a somewhat thirst motor.
Have you got a photo of the transformer? As said above, the terminals sound like an AC transformer. I would suggest SCN is 'screen'?
What make is the loco(s) that are 'thirsty'? You may be able to supply 20v DC (the locos will be rated for 12v) but a lot of locos, especially Heljan, need around 1amp and 0.7amp just won't cut it.
What make is the loco(s) that are 'thirsty'? You may be able to supply 20v DC (the locos will be rated for 12v) but a lot of locos, especially Heljan, need around 1amp and 0.7amp just won't cut it.
SCN is definitely screen and should be connected to mains earth. Its purpose is to ensure that mains voltage cannot appear on the secondary terminals in the event of the transformer becoming faulty.
I will send a photo tomorrow. You are probably right about the load but it would sill be nice to use the thing. The engine I am wanting to make go is a sound equiped Intermountain American job (Canadian National FP9A). It is supposed to have basic sounds on traditional control but it needs a bit more power than the usual 12volts to run it, I was warned about that when I bought it (second hand). I could buy a DCC set up to run it but again it would have to be a larger output to run it and the cost of going completely DCC is not in my budget.
Yup, DCC is expensive to set up. I bought a 2nd hand kit built set up. Works okay except I can't get it to change the id number on locos. Bit of a bugger when they are all set to the default 3. I've never tried any Intermountain stuff. Got an assortment of Athearn in CN and the late BCRail. Got a really soft spot for the SD40.
If it's one of these, the output is definitely AC.
The writing means it is rated to provide 0.7A at DC after rectification, not that DC comes from the terminals.
You will need a separate bridge rectifier as well.
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Centre tapped transformer, so would normally used with two diodes, rather than a bridge.
How true. Didn't engage brain for that bit
My transformer looks similar to the one you pictures, also made by RS. I will have a dabble with it and see what I can find.
I have spent a life time collecting mainly American outline toy trains, far to many if the truth be known. I rather like the earlier diesel era and in particular the Spokane Portland and Seattle with its many Alco's (RS3's burbbling away, brilliant). The SD40's are rather stricking, especially the long snout variety. Who had the best livery I wonder, I like the original Canadian Pacific colours (not the action red) but of course the BC Rail green livery takes some beating.
I went American more decades ago than I care to remember with Athearn (followed later by Atlas) because they worked so much better than the British trains did. Things have of course changed and a rather nice model of a Bachmann class 40 apply demonstrates that. All good fun and keeps whats left of the brain working.
I have spent a life time collecting mainly American outline toy trains, far to many if the truth be known. I rather like the earlier diesel era and in particular the Spokane Portland and Seattle with its many Alco's (RS3's burbbling away, brilliant). The SD40's are rather stricking, especially the long snout variety. Who had the best livery I wonder, I like the original Canadian Pacific colours (not the action red) but of course the BC Rail green livery takes some beating.
I went American more decades ago than I care to remember with Athearn (followed later by Atlas) because they worked so much better than the British trains did. Things have of course changed and a rather nice model of a Bachmann class 40 apply demonstrates that. All good fun and keeps whats left of the brain working.
As said above, if it's like the one in the photo then it'll be AC which will need to be rectified. DO NOT connect AC to your locos.
The Canadian stuff started with me back in 1996 when I had a 3 week RV holiday in Canada. As you say, back then the American outline stuff was better than the UK stuff. My main collection these days is early UK diesel. Just love the sight of the LMS 'twins' but as I'm from S.Wales the class 37 will still be my favourite . I'm after a Heljan 28 C0-B0 at the moment but prices are going silly for stuff these days. There's people asking over £320 for a Kernow Bullied diesel. They were around £170 when they came out.
The Canadian stuff started with me back in 1996 when I had a 3 week RV holiday in Canada. As you say, back then the American outline stuff was better than the UK stuff. My main collection these days is early UK diesel. Just love the sight of the LMS 'twins' but as I'm from S.Wales the class 37 will still be my favourite . I'm after a Heljan 28 C0-B0 at the moment but prices are going silly for stuff these days. There's people asking over £320 for a Kernow Bullied diesel. They were around £170 when they came out.
Won't you get an interesting smoke effect if you run older motors on A.C.? DCC of course uses AC so it does get confusing, it has a flattened off wave form or something, also used in controlling the speed of diesel electric ships and that does get technical.
I have bought very little in the way of models (or toy trains as I call them) of late because of stupid prices. It has gone very silly, it seems the affluent have the model train bug.
The 37's were and still are rather fine machines, triple headed iron ore trains going to Llanwern through Cardiff Central (was it General then?) were rather spectacular (and noisey). I never saw the LMS twins, but I do have distant memories of the Co-Bo's on the Midland mainline in the Peak District (where I am originally from). I was rather small then and was far more interested in the steam trains.
The Heljen models are very fine, I have scimped and saved and am waiting with bated breath for their model of the class 104 DMU which was a stalwart on the Buxton trains for years, those I do remember well. In the winter the diesel fumes that came free with the heating would send you nicely to sleep by the time you reached Hazel Grove. You got used to the resulting headaches after a while, a cheap hangover really.
I have bought very little in the way of models (or toy trains as I call them) of late because of stupid prices. It has gone very silly, it seems the affluent have the model train bug.
The 37's were and still are rather fine machines, triple headed iron ore trains going to Llanwern through Cardiff Central (was it General then?) were rather spectacular (and noisey). I never saw the LMS twins, but I do have distant memories of the Co-Bo's on the Midland mainline in the Peak District (where I am originally from). I was rather small then and was far more interested in the steam trains.
The Heljen models are very fine, I have scimped and saved and am waiting with bated breath for their model of the class 104 DMU which was a stalwart on the Buxton trains for years, those I do remember well. In the winter the diesel fumes that came free with the heating would send you nicely to sleep by the time you reached Hazel Grove. You got used to the resulting headaches after a while, a cheap hangover really.
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