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Testing lighbulb using multimeter

zillah

Mar 4, 2012
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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
 

jackorocko

Apr 4, 2010
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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.
 

zillah

Mar 4, 2012
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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.
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
 

jackorocko

Apr 4, 2010
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productLarge_11348.jpg


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.
 

jackorocko

Apr 4, 2010
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My digital multimeter wouldn't be able to read resistance not continuity,,,,,I couldn't figure out where is the problem !!!!!

Maybe you should clarify what this means??

Auto Range, 4 Digit, True RMS, Transistor Test, Diode Test,10A AC & DC Current, Data Hold, Continuity Buzzer, 40MOhm Resistance,Temperature,Capacitance, Frequency, Relative Measurement, Auto Power Off, Duty Cycle, Cat III 600V, Holster,
Temperature Probe

It has everything you are asking about, are you not sure how to use it?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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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.
 

zillah

Mar 4, 2012
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are you not sure how to use it?
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
 

jackorocko

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

zillah

Mar 4, 2012
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OL stands for OPEN LOOP. Which means it has infinite resistance. There is a break somewhere in the circuit between the two probes.
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
 

siggy

Mar 3, 2012
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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:

Rleo6965

Jan 22, 2012
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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.
 

siggy

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


More like 0.1ohm
 

jackorocko

Apr 4, 2010
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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
 

siggy

Mar 3, 2012
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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
 
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