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What is the difference between bc547 and 2n2222A transistor. I have use bc547 for a project (Water level indicator). Can i use 2n2222A instead of bc547? How each transistors are selected for each project?

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    \$\begingroup\$ What does comparing the datasheets tell you? \$\endgroup\$ – winny Dec 26 '16 at 7:53
  • \$\begingroup\$ Trivial questions that only require reading the datasheets should be closed. \$\endgroup\$ – Leon Heller Dec 26 '16 at 8:35
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    \$\begingroup\$ First you should understand how transistors work and what their key parameters are. Then you should learn how to read datasheets in general. Finally you have to compare the datasheets of multiple transistors to determine which one suites your requirements best. Most datasheets provide a list of typical use cases for the component. Here are some tips on how to read a datasheet. Here too. On transistor basics \$\endgroup\$ – try-catch-finally Dec 26 '16 at 9:14
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There is not much difference when it comes to electrical properties of the two transistors. You can have a look at the datasheets :

The two major differences that I find are:

  • the power dissipation (a measure of power that transistor can provide):

    2N2222A - 625mW

    BC547 - 500mW

  • collector current (output current in common emitter config):

    2N2222A - 600mA

    BC547 - 100mA

So your application defines your selection in such cases. If you need more current amplification for same biasing voltages you might want to go for 2A2222N.

Read the datasheets carefully and make your choice.

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    \$\begingroup\$ The basic difference is the 2N2222A is explicitly labeled "switching mode transistor", which explains the much higher collector current in the same casing. One has to expect bad linearity and high output capacitance from that. The same part may be labeled BU_nnn in the Philips scheme. \$\endgroup\$ – Janka Dec 26 '16 at 9:33

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