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Which datasheet to use?

chagz

Jan 4, 2010
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Jan 4, 2010
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I am trying to design a 2 stage BJT amplifier and I am having trouble choosing a spec sheet for the 2N2222A transistor which I am using. Normally, when i buy my parts, the spec sheet is not usually provided. So i decided to look for one on the internet using datasheetpro.com, the search engine. Unfortunately I discovered that different manufacturers may have slightyly different values of hfe. One is from 100 to 300, another is 75 to 300. Which value should I use?or is there any way I can match my transistor to a specific datasheet?
 

shrtrnd

Jan 15, 2010
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Jan 15, 2010
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If you can see the manufacturer's logo on the transistor, you should be able use the manufacturer's data sheet. The parameters are different because the 2N2222A is available in both plastic (TO-92 type) packages, and also in steel or aluminum cans.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Use the worst one (75-300) that way any design decisions you make will not require that you specify a 2N2222A from a particular manufacturer.

If this is just a one-off, you could measure the gain and then you'd know -- the specs don't tell you about the device you have in your hand, they tell you about the population of devices manufactured.
 
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