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Reply to "Semaphore and 555 Timer Circuit"

Adriatic posted:

   I didn't look to see exactly how the applies, But CBE postions on a component should'nt be taken for granted. I've ad suppliers throw curveball odd numbering additions into normal packaging needing two legs cossed and/or reverse placement. Read the included data sheets every time .

Back in the day, Radio Shack would sell a grab-bag of random and cryptically marked transistors. No data sheets included.  But a hobbyist willing to spend the time could save some money sorting through these.  While I can't imagine anyone doing this today, I see that the "FREE with coupon" Harbor Freight DMM still offers the so-called hFE transistor-test function which allows you, in effect, to determine the CBE orientation of a transistor as well as its polarity (NPN vs. PNP).  Here's the meter set to hFE mode with an NPN with the EBC orientation showing an hFE (current gain) of ~200.

free HF meter hfe tester

Unfortunately, this is NOT suitable for working with FETs.

 

 

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  • free HF meter hfe tester

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