dimming ac led bulbs?

Discussion in 'Ham Radio Discussions' started by KB4MNG, Dec 2, 2019 at 10:28 PM.

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  1. KB7WG

    KB7WG Ham Member QRZ Page

    I need to get out more.
     
  2. WZ7U

    WZ7U Ham Member QRZ Page

    You ain't missing nothing
     
    W1TRY and KQ9J like this.
  3. AA7QQ

    AA7QQ Ham Member QRZ Page

    First, you need to check the packaging of the lamp to see if the unit is "Dimmable".
    Then, you need to get an LED compatible dimmer.

    Ed
     
  4. K6CLS

    K6CLS Ham Member QRZ Page

    All the dimmers make noise on MF and HF.
     
  5. KB7WG

    KB7WG Ham Member QRZ Page

    I gotta watch what I'm saying, haven't been out in a while. It has an AC socket. So I would assume that it would need an AC dimmer, not a LED dimmer........is that right?
     
  6. AF7TS

    AF7TS Ham Member QRZ Page

    All LEDs need some sort of driver circuit, to properly regulate the current through the (very) non-linear LED junction. The ability to dim an LED bulb depends on how the driver circuit plays with the dimmer output.

    A perfectly regulating LED driver would keep the output constant even as the input RMS voltage changes; in other words a perfect constant current driver would _ignore_ the dimmer.

    Some LED driver circuits detect the waveform changes caused by a normal dimmer, and use this information to adjust the output current. In this case the dimmer has to change the AC waveform in a way that the driver can understand and detect...put such a LED lamp on a variac dimmer and it won't dim.

    In this context an 'LED dimmer' is an AC dimmer that specifically plays nicely with the drivers in the lamps. Most dimmers get their power by being in series with the load, so an LED dimmer is designed so it will be properly powered in series with an LED, and that the output waveform is something that an LED will respond to. These things more reliably simply work, but really what you need to do is test the lamps you want to use with the dimmer you want to use.

    -Jon
     
  7. WA9SVD

    WA9SVD Ham Member QRZ Page



    Unfortunately, your original dimmer was NOT designed for fluorescent bulbs. They DO need specific dimmers, and can be considerably more costly than dimmers for incandescent bulbs. The down side is quick failure, or even fire.
     
  8. K8HIT

    K8HIT Premium Subscriber QRZ Page

    I was recently examining that style bulb at Home Depot. I'm not sure if it applies to all LED filament bulbs, but the one I was looking at had less RFI than other LED and therefore was a good choice for use in a garage door opener.

    Perhaps this is a desirable bulb for the shack.
     
  9. KB4MNG

    KB4MNG Ham Member QRZ Page

    The 12 v DC small flood lights are awful far as rf. I fix up a nice ceiling lamp for my shack and would power up when I powered my radio console. The rf produced much noise on the rig and would totally knock out my tivoli fm radio. Also, I tried to run one in my garage and it severely limited the range on the garage door remote.
     
  10. KW4GT

    KW4GT Ham Member QRZ Page


    Not necessarily so. I've got LED compatible dimmers with LED lamps in my house and never hear a bit of noise on HF. Maybe I just got lucky, but I can attest to the fact that it most certainly is possible to have dimmable LEDs without RF noise.

    As to someone else's comment about the life of LED bulbs..... I switched all my lights to LED over 5 years ago and haven't replaced a single one of them yet, so besides consuming a fraction of the energy as antiquated incandescent bulbs they really do last much much longer.
     
    W9FL likes this.

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