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Specifying a relay

Discussion in 'Electronic Basics' started by scouselad, Oct 22, 2007.

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  1. scouselad

    scouselad Guest


    I'm looking for a couple (excuse the pun) of relays to control a
    lighting circuit and a heater. The lighting circuit will be a load of
    <1A, and the heater will be <5A, although I'm not sure if the heater
    is purely resistive or not. Currently, I'm leaning towards an SSR, the
    Crydom SDV2415R, but now I've been told I should buy a zero-crossing
    version, particularly for the lighting circuit since random turn-on
    can, apparently, damage filament bulbs.

    So, I'm a little confused as to what I should buy. Also, I'd like to
    be able to "dim" the lights - or, at least, to change them between a
    few different levels from "mood lighting" up to full illumination.
    (This will be based on a digital light sensor, but that's a different
    subject entirely.) However, I'm not sure if an SSR can react fast
    enough for me to use PWM (which my MCU can output natively) - I'm just
    not sure which figure on the datasheet I should look for - and they
    don't seem to have any sort of transient by which I could accurately
    control the current allowed through/the voltage across the AC output

    So, perhaps what I need isn't a relay, but some other sort of

    I hope you can help,
    Allan Lewis.
  2. ehsjr

    ehsjr Guest

    Use a triac to dim the lights. Google "triac dimmer".
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