Connect with us

Light bulbs as dummy load for Stereo ?

Discussion in 'Audio' started by techforce, Sep 9, 2019.

  1. techforce

    techforce

    6
    0
    Dec 26, 2008
    Was curious if anyone has done this before, instead of using resistors or other test gear as the load in place of actual speakers to protect the speakers?
     
  2. Alec_t

    Alec_t

    2,663
    702
    Jul 7, 2015
    If the bulb replaces the loudspeaker, i.e acts as a dummy load, then clearly the loudspeaker is protected :confused:.
    Did you mean use the bulb as a dummy load, or use the bulb in series with the speaker to limit current?
    Bear in mind that the bulb rating specifies wattage at the rated voltage when the bulb is hot. The bulb's cold resistance is a lot lower than its hot resistance.
     
  3. dave9

    dave9

    773
    171
    Mar 5, 2017
    You mean something you built yourself, or repaired, and question its proper function? I usually just measure to be sure there's no DC on the output (if applicable), then first hook the amp up to crappy low value speakers, actually just a loose driver I got out of something or other a long time ago.
     
  4. Martaine2005

    Martaine2005

    2,394
    630
    May 12, 2015
    Why would you want to put a bulb in place of a speaker?,
    A 120v, 60w bulb is 240 Ohms....

    Martin
     
    davenn likes this.
  5. Alec_t

    Alec_t

    2,663
    702
    Jul 7, 2015
    .... but maybe < 50 Ohms when cold.
     
  6. Martaine2005

    Martaine2005

    2,394
    630
    May 12, 2015
    True.
    Martin
     
  7. dave9

    dave9

    773
    171
    Mar 5, 2017
    Series parallel array of incandescent bulbs in a freezer with a thermal detection liquid nitrogen spray for the win!
     
  8. techforce

    techforce

    6
    0
    Dec 26, 2008
    Yes as a dummy load. I was thinking a100w floodlight maybe. Just to protect the speakers from possible excess DC when
    doing repairs. I have something like 80mv on one channel as DC offset, and the other is about 0v , doing the tests with
    nothing attached to the spkr terminals. Its a Pioneer SX-240 Stereo and the protect relay keeps clicking out at about 33% volume.
    There was alot of cracked solder on the spkr terminals, and one on the coil for the relay.


     
  9. Externet

    Externet

    711
    145
    Aug 24, 2009
    An automotive 12V 55W head lamp can fake a ~5 ohm load.
     
    techforce likes this.
  10. dave9

    dave9

    773
    171
    Mar 5, 2017
    Won't a 12V bulb be too near the amp output voltage to keep the resistance anywhere near constant?
     
  11. Alec_t

    Alec_t

    2,663
    702
    Jul 7, 2015
    An electric kettle element would run at a lower temperature than a bulb filament, so the hot/cold resistance variation would be less.
     
  12. techforce

    techforce

    6
    0
    Dec 26, 2008
    Interesting idea. Maybe a spare electric stove coil would also do the same thing.

    Good idea @Alec_t about the bulb in series with the speaker.

     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-