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Thread: 'Wall Wart' power supplies in series/parallel?

  1. #1
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    Default 'Wall Wart' power supplies in series/parallel?

    Hi,

    I've made four mini trees. Each is wrapped with a string of 150 mini lights. Each set of lights comes with a 36VAC 'wall-wart' plug-pack style transformer. I've got four identical transformers, one per mini tree.

    I want to control these using my Olsen 595/SSR co-op hardware. Being in Australia we don't generally switch 240VAC (our mains voltage) via an SSR. As a result I've got a couple of co-op SSR's configured to switch 36VAC.

    The SSR's switch off a common power supply. Because I don't have a dedicated 36VAC power supply capable of powering all four trees at once, I was wondering if it is possible to wire the four (identical) 36VAC wall warts in such a way that I can power all four mini tree's and switch the power through a single 36VAC SSR.

    Any advice is greatly appreciated.

    Thanks in advance,

    Grant

  2. #2
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    Hi Grant,

    I found it so much easier to use a dedicated TX instead of the plug packs. About all you could really do by the sounds of it is join all of the actives together and same with the neutrals and then run the active from the plug packs into the AC input of the SSR.

    I'm sure the loading on the plug pack will be shared evenly over the 4 units.

    Connect in your switched actives into the SSR terminals 1-4 and join all nuetrals together and fire the sucker up and see what happens

    If you don't want to go done that track then your next best bet would be a 240-36volt transformer 160va would be fine.

    Dennis
    Sometimes things appear harder then what they are, don't give up, just try harder..

  3. #3
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    Thanks Dennis.

    I really wish I could go out and buy some transformers, but I'm afraid the wife wouldn't be too happy given the money I've spent on lights, etc, recently.

    I'll try wiring the outputs of the AC adapters together and see what happens! (I might throw my multimeter across it first!).

    Thanks again,

    Grant

  4. #4
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    why not just switch 240, not that hard

  5. #5
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    Mulitmeter, I should have said that being an electrician
    Sometimes things appear harder then what they are, don't give up, just try harder..

  6. #6
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    I wouldn't wire the outputs of the adaptors directly together. The adaptors are going to have slightly different voltages (not by a lot, but still), and one or another would end up supplying most of the current (especially if you get one of them backwards).

    My inclination would be to wire one side of the transformers together, the other side of each transformer going to one light string, and then wire the other sides of the lights strings together. Make sure, of course, that the transformers are all in phase with each other.

    --

    Phil

  7. #7
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    http://polk-burnett.apogee.net/pd/dsdo.asp

    That page contains some info regarding the requirements to meet before paralleling 2 transformers.

    If done properly it can increase the supply current.
    Thanks,
    Brian, your friendly site Admin.

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