Connect with us

Testing lighbulb using multimeter

Discussion in 'LEDs and Optoelectronics' started by zillah, Mar 4, 2012.

Scroll to continue with content
  1. zillah

    zillah

    21
    1
    Mar 4, 2012
    Hi Experts

    I have got DIGITECH Cat: QM-1536 Multimeter bought around $80 from

    http://www.jaycar.com/splash.html

    Tried to test two types of bulbs to check if it is burned out or not

    The first one Compact fluorescent light bulbs (CFL) similar to one in the link below

    http://www.ehow.com/facts_6019356_energy-saving-bulbs-vs_-mercury.html

    And the second one typical incandescent bulb ( I guess it is called light bulb) the one similar in the link below :

    http://www.ehow.com/how_7526571_test-light-bulbs-continuity-meter.html


    When I did the test I followed the instruction in the links below :

    http://www.ehow.com/how_5193668_check-bulb-other-light-bulb.html

    http://www.ehow.com/how_7526571_test-light-bulbs-continuity-meter.html

    My digital multimeter wouldn't be able to read resistance not continuity,,,,,I couldn't figure out where is the problem !!!!!

    Thanks
     
  2. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    resistance and continuity are closely related (inversely proportional???), the more resistance the less continuity, vice versa.

    A good incandescent bulb will have a low resistance compared to one that is blown, with infinite resistance.
     
  3. zillah

    zillah

    21
    1
    Mar 4, 2012
    Hi jackorocko
    My thread still pending to an answer which is why the multimeter that I have got doesn't apply the theory that you have mentioned in the quote above ?
    Thanks
     
  4. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    I can't even find the DMM that you are talking about.
     
  5. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    [​IMG]

    Is it this one? the ohm setting is from 9 o'clock to 11 o'clock Just below 200Ohms is the diode tester, it will give an audible beep when the circuit is closed loop. Works perfect for continuity tester.
     
  6. zillah

    zillah

    21
    1
    Mar 4, 2012
  7. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    Maybe you should clarify what this means??

    It has everything you are asking about, are you not sure how to use it?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,500
    2,840
    Jan 21, 2010
    Maybe it works for the incandescent bulb and not the CFL.

    The failure mode of the CFL is different than for an incandescent bulb. It probably won't measure too much different from a working one in terms of resistance.

    I found a link recently which explained how they are designed to fail at end of life and it's pretty interesting. How to avid smoke and acrid smells. Not completely relevant to this thread, but that type of failure cannot be seen by measuring the input resistance.
     
  9. zillah

    zillah

    21
    1
    Mar 4, 2012
    Yes this is what I have just realized that from other forum.
     
  10. zillah

    zillah

    21
    1
    Mar 4, 2012
    What I meant to say when I tried to do a test on a working light bulb , I used the DMM to check the light bulb ( pin type or push and turn not a screw type ) resistance I would expect the resistance value should be some reasonable reading,,,,,but in my case reading was 0.L Mega ohms
     
  11. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    OL stands for OPEN LOOP. Which means it has infinite resistance. There is a break somewhere in the circuit between the two probes.
     
  12. zillah

    zillah

    21
    1
    Mar 4, 2012
    Okay since I am using the pin type light bulb and all online instructions that I have been through are explaining the screw type light bulb.

    For the pin type light bulb we put the probes on the tips of the light bulb ? don't we ?

    Regards
     
  13. siggy

    siggy

    36
    3
    Mar 3, 2012
    0.L means overload or out of range or infinity i.e. open circuit or unable to read......... lightbulbs if they glow when inserted into holder and turned on are good. If not b1n them


    Dang beaten to it!


    Well it's 08:58 suppose i should get up earlier lol
     
    Last edited: Mar 4, 2012
  14. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Have you tried test your multimeter probes have no loose connection or reads inaccurate reading? Should reads low resistance around 1 ohm if probes tips shorted together.
     
  15. siggy

    siggy

    36
    3
    Mar 3, 2012
    That high of a reading and I'd get rid


    More like 0.1ohm
     
  16. zillah

    zillah

    21
    1
    Mar 4, 2012
    Yes it is 0.3 or 0.4 ohms less than 1
     
  17. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    what do you mean when you say pin type bulb? If it is what I am thinking of, then the outer casing is one lead of the bulb and the bottom of the bulb is the other pin(like on a screw type bulb)

    Show us a picture of the bulb
     
  18. siggy

    siggy

    36
    3
    Mar 3, 2012
    On e pin type or bayonet bulb the two terminals are the silver/grey bumps at the bottom not the side case

    The other is es or edison screw that would be case and single silver grey bulbs
     
  19. zillah

    zillah

    21
    1
    Mar 4, 2012
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

-