Multimeter test

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ROSELJR

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Jul 15, 2021
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Hello everyone , I just bought NE556 yesterday, but I don't know whether it is reeal, so how to use a multimeter to test the NE556 chip?
If you know, please tell me, thank you.
 

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JohnRoberts

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a VOM alone is inadequate to fully test an IC. Generally you need to perform a functional test, i.e. putting it into an operational circuit.

JR
 

rackmonkey

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John is right. But you can usually see if it’s even worth wasting time setting up a test circuit by using your DMM or LCR tester to measure resistance between Vcc and either Output pin. Fake chips will usually measure open or significantly off from the DCR reading you’d expect using that measurement. For reference, a real NE556 measures around 12k DCR between the two (pin 14 to either pin 5 or pin 8). Anything very far off from that and you’re probably best moving on.

Doesn't always work, depending on which original IC was sanded down and relabeled, but it does most of the time.
 
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PermO

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Mar 16, 2011
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A friend of mine once got some fake IC's from China, he figured fake IC's were just relabelled random IC's...
Well... it didn't meassure anything ?

So he decided to cut it open...

It was just a plastic blob with 14 pins... they probably ran out of random IC's.
 
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