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Converting AC to DC for LED conversions

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  • Converting AC to DC for LED conversions

    Here is a schematic I use for converting 110+V AC to DC. It is pretty simple overall, but be forewarned...this type of power can really hurt or even kill you. Don't be too scared, though. Just be patient, work slowly and pay attention to what you are doing. If you need help...ASK! If not from me then please find someone else who is comfortable with this stuff.

    Most older clocks up until the mid/late 1970's were powered by main power directly from the wall, but still used an internal transformer type power supply. There was no need to drop the power much because they were using neon/nixie type tube lamps for the warm orange glow and those are power hungry. Those required around 85 volts and were simply stepped down from 110/120 to around 85 volts with a big fat resistor. Ultra simple.

    For LEDs we need to step the power way, way, way down below 5 volts depending on the LED harness you have designed. It also needs to be converted to DC or the LEDs will flicker. Most LEDs require 1 to 5 volts depending on color and size. I use warm white "straw hat" LEDs because the color is nice and mellow and the straw hat configuration give a wider area of light...a wide beam. I usually use 2 per harness and that seems to give good coverage depending on the clock chassis I am working in. That's probably overkill, but it works and customers seem to enjoy it. I recently refurbished a Panasonic RC-6551 "Bulldozer aka Digi-Dater" and it took a total of 8 LEDs! 2 (overkill!) for the alarm wheel (which is plastic and translucent), 2 for the day/date, 2 for the big time digits and 2 more for the wide tuning barrel. The tuning barrel also required a custom bracket to hold the lights pointing forward as the "buss" type lamp was in a bracket that was not conducive to LED usage.

    Another note of caution...this method of an unregulated "transformerless" power supply can be dangerous if certain cautions are not observed. Check your work, test well, get help if you need it or have questions. Also, when the circuit is constructed and securely mounted, as long as it is very well insulated from anything that could short the circuit, it should be safe inside of an enclosed case.

    SEE ATTACHED SCHEMATIC. This is my diagram, but it is made with personal knowledge and from the internet with others who have been doing it way longer than me!
    Attached Files
    Last edited by timerider; 4 days ago.
    www.timerider.net

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