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Discussion in 'General Electronics Discussion' started by Clive, Aug 19, 2016.

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  1. Clive


    Aug 19, 2016
    Hi all

    I have very little if any knowledge of electronics and need some advice. The problem I have is a need to be able to run up to four different devices using only one power cable. I have a 29v device and 2 to 3 12v devices, is there a way of using the output from the 29v transformer and converting it to 12volts.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Are the voltages AC or DC?

    If AC the theoretical answer is yes but the practical answer is no.
  3. Clive


    Aug 19, 2016
    trans.JPG trans2.JPG trans3.JPG
    These are the transformers I would like to combine. The transformer in the middle is what i would like to feed another transformer that could out put the 12v and the 15v and 29v to power the devices these transformer now do seperately.
  4. BobK


    Jan 5, 2010
    Yes, you can convert 29V to 12V using a DC to DC converter. But one thing you must check is whether it can supply enough power for all the devices, taking into account that maybe 20% is lost in going from 29 to 12V.

    So, add up the power utilized by all 4 devices. Power for each is voltage x current. The calculate the output of the 29V supply (not transformer, these are switching power supplies). The output should be at least 1.25 x the needed output, and I would be wary if it was not more like 1.5X.

    If one if the devices powered is the one intended to be powered by the 29V supply, it is unlikely that it will have enough extra power for the other devices unless their requirements are small compared to the 29V one.

    (*steve*) likes this.
  5. Minder


    Apr 24, 2015
    First is the 29v transformer at the AC secondary or at the DC level, as a 29vac transformer secondary will give you ~40vdc after rectification and smoothing.
    Secondly, does the 12v circuits require a regulated supply or are they a type of load that it is not really necessary such as a LED or Motor load etc.
    If you have a transformer where the secondary is a lot higher than required, often secondary turns can be removed, it is a bit harder for the E I style over the toroidal type, which are usually real easy.
    Fortunately the secondary is wound on last and it usually equates to 3-4turns/volt to 1.5-2turns/V for each type.
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