Converting AC to DC

  1. Hi everyone i am Julius a 400L student, this is my first post as a new member of this great forum. Please,i want to know a step by step practical guide on how to convert AC to DC , i join this forum for me to properly learn (PRACTICAL) from the masters here and it will be my pleasure if i can have at list 90 percent of help i need in this forum to succeed in my future career i am having less that 1 year to finish my program at the university waiting for your positive repose thanks.
    Last edited by a moderator: Jan 20, 2014
  2. jcsd
  3. OmCheeto

    OmCheeto 1,946
    Gold Member
    2014 Award

    Hello juliusabidoye,

    In the olden days, we used full wave bridge rectifiers, with a capacitor on the output, to smooth out the pulses.


    I would imagine there are other ways to do this, by now.
  4. sophiecentaur

    sophiecentaur 13,405
    Science Advisor
    Gold Member

    In the even older days, they used to use just a single diode (rectifier) with a reservoir capacitor, which is not always needed if all you want is 'unidirectional current' rather than a steady DC voltage. Those Selenium Rectifiers were expensive, iirc - and pretty rubbish, too.
    Did you look at Wikipedia? Here is a link.
  5. Converting Ac to DC is the most generic way to describe this, as Sophie points out it can be done with one Diode, from there the systems become more and more complex, each method had it's own benefits, drawbacks and pittfals - while this can be studied on paper ( internet - etc) - but IMO building each type will have the best impact.

    I would start with a small step down transformer as an ac source ( get an adviser to help and make this to be safe), and build into a small experimenters box. 120VAC to 12-0-12 Secondary. This will provide 12V or 24V AC source. ( On the AC side, you will need the plug, a fuse, and a properly rated switch), bring the 3 low voltage leads to binding posts.

    From this you can build rectifier circuits with the 1, 2, 4 Diodes, and experiment with different filtering etc. on a basic breadboard.

    Some type of basic oscilloscope will be best to see what is going on - a PC one will, do but the inputs need to be limited to ?? 0.7V? - I am not sure, but you can build a basic voltage divider probe 100/1 to keep the ratios in check. I would also advise to "build" each circuit in Spice ( LTSpice is free) - before you build the real circuit - then compare the Spice results with your real world results.

    A set up like this could support about 20-40 AC/DC conversion experiments. I have been thinking of developing this as a web-curriculum, but I would reference a suppler like radio shack for parts ( as I am based in the USA) -the Safety aspect of the AC supply is my biggest concern.
  6. well i want to sincerely appreciate you all that contributed to my thread i want to say i have find your information helpful thank you and God bless you.
  7. sophiecentaur

    sophiecentaur 13,405
    Science Advisor
    Gold Member

    There are quite a few of these things available and they are of various qualities and voltages. It is possible that there is a thermal cutout to avoid overheating but it would be a good idea to provide yourself with a 2A fuse (in line type, perhaps) to protect it with. Probably the cheapest way to get your 'safe' AC supply to work with.
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