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Extremely basic circuit help required!

Discussion in 'General Electronics Discussion' started by Grumple, Jun 22, 2015.

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  1. Grumple


    Jun 22, 2015
    Hi all, I have absolutely no idea what I'm doing when it comes to electronics - but I am fairly handy and like to try different projects.

    I am attempting to build a small meat drying box.

    I want to be able to plug it into a mains socket, and need to power a single light bulb (up to 100w) and a computer fan (on 12v power).

    My basic plan is:
    Plug from mains into 250v 10A rated 3 pin computer power socket with switch.

    Cable from power socket to split.

    1 cable goes to 240V AC to 12v DC transistor - cable goes to fan speed controller then to 12v computer fan.

    1 cable goes to 2nd switch then onto bulb holder for bulb up to 100w.

    My main confusion is coming from what to do with the earth core from the mains power cable, and then what fuse I'll need for the bulb/switch and where it should go.

    It's early days and I'm nowhere near wiring anything, I just need to define the circuit properly.

    I know this is child's play to most on here, but it's my first electronic project and any help would be really appreciated!!

  2. BobK


    Jan 5, 2010
    If the box is metallic, connect the ground wire to the box. Otherwise, leave it unconnected.

    There is not much point in using a fuse in line with a light bulb. The bulb will act as a fuse all by itself.

  3. Grumple


    Jun 22, 2015
    Hi, thanks for the reply!

    I've not been around my computer for a while, so apologies for the delayed response.

    The box will be wooden, so I can't earth to the unit itself.

    This is the mains socket I am thinking of using (because it's convenient and switched) -

    From this socket I want to wire up a light bulb (with it's own switch), and a 12v computer fan (which will come on when the main power switch is on).

    So I'll need to split the cable from the socket:
    - One cable going to a transformer and then onto the fan
    - One cable going to a 2nd switch and then onto the light bulb

    I was told I would need a fuse in order to lower the amps before a switch for the light bulb -
    Switch -

    This is the only rocker switch like this that I can find that is 250v rated - 99% are 12v, but I need mains power in order to power a standard 60w light bulb (don't I???) -
    Bulb holder -
    Light bulb -

    Is there a better option for the mains power socket?
    Would it be better to put the transformer straight after the power socket and find a 12v light bulb?

    It seems like a simple enough circuit to me - but I just need to understand what to wire to what!

    Thanks all

    Attached Files:

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