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What did I do wrong!

  • 24-10-2015 10:32am
    #1
    Registered Users, Registered Users 2 Posts: 1,742 ✭✭✭


    Hey guys I'm a novice but have built simple circuits with arduino boards so not completely incapable! I've put together a project with an arduino Leo, Ethernet shield and 4 channel relay board to interface with my boiler controls.

    The project works well but I'm having problems powering it. I wanted to dispense with the wall wart adaptor and use a 230v to 12v dc transformer and then a 12v to 5v switching psu.

    I've used the 12v to 5v switching psu from 12v DC batteries and it's worked fine but connecting them to the 230/12v transformer just cooks them in a couple of mins!

    I've burned 2 so don't want to loose any more am I doing something fundamentally wrong?


Comments

  • Registered Users, Registered Users 2 Posts: 2,320 ✭✭✭Chet T16


    Are you sure it's 12v dc coming out?


  • Registered Users, Registered Users 2 Posts: 1,742 ✭✭✭tnegun


    Chet T16 wrote: »
    Are you sure it's 12v dc coming out?
    I couldn't get a reading on the multi meter I've got 2 230/12v transformers so when the first blew I tried the second with the same result and thought it unlikely that both 230/12v transformers where faulty and must be my design but I did salvage both from electronics destined for the bin!


  • Registered Users, Registered Users 2 Posts: 2,320 ✭✭✭Chet T16


    If they're actual transformers then they'll be ac output which is why your meter can't read a dc voltage. You'll need to rectify that output and stick a cap across it before sending it to your 12v -> 5v circuit


  • Registered Users, Registered Users 2 Posts: 1,742 ✭✭✭tnegun


    That would make sense I had drawn power from one before but it was still plugged into an alarm panel at the time so I guess the panel had a rectifier built in. Thanks for the help!


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