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High-side LED dimming

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  • High-side LED dimming

    Hi everyone.
    Recent member here, and that's my very first post.

    I'm doing a classic car restoration/customization and I have, amongst many updates, a mini-itx mb and 7" screen waiting to bring my car into the current millenium.
    I'm also planning stuff with arduinos and OLED....

    But today's question in not about the carputer itseft, it's about LED.

    DISCLAIMER: I got banned without notice from a forum for asking that seemingly simple question, so if I'm breaking any forum's rules , pleeeease, let me know beforehand.

    Here is it:
    I want to convert my dashboard lights to LED (about a dozen of 50mA SMD leds replacement bulb), and I want to be able to control the dimming level. Eventually by the computer, but let's start with a simple physical knob for the sake of simplicity.

    I found out that almost all led dimmer works on the low side of the circuit, plugging themselves between the led and the ground.
    Looks like it's the sound way to do it electronically speaking.
    Since each bulb take its ground locally on my car, I would have to add an extra wire everywhere and change all my bulb sockets.
    So I started to investigate high side switching (between the 12v source and the led), learned a bit about 555 dimming, P-channel & N-channel Mosfets and such.
    As much as I can implement existing schematic, I'm definitely not confident designing my own.

    Anyone knows about existing product? Any available design I could etch? or I'm just plain foolish and should rewrite my harness for a standard dimmer?