Timeline for What is the impedance of this Common Emitter transistor
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| May 4, 2018 at 23:16 | comment | added | Henry Crun | The power supply is rather assumed to be a short circuit for everything the circuit is going to throw at it. To ensure that, we put fat capacitors and little capacitors, both, across it. | |
| May 4, 2018 at 23:12 | comment | added | Henry Crun | The word I used was "approximation" . 25 ohms is seldom significant, so I don't need to consider it. An engineer is a man who knows that 2+2 is close enough to 4 | |
| May 4, 2018 at 20:11 | comment | added | Duck | you say R1 // R2 // Re*HFE but shouldn't rEE be considered too? R1 // R2 // (Re + rEE)*HFE? I don't get your last paragraph... sorry I am newbie. | |
| May 4, 2018 at 20:06 | comment | added | Duck | do you mean that the power supply is a "short circuit" for AC signals? Interesting... | |
| May 4, 2018 at 19:46 | comment | added | Henry Crun | R1 is connected to an AC ground point: VCC. So it is an AC impedance to ground in // with R2 and the base | |
| May 4, 2018 at 19:43 | comment | added | Duck | I do not understand why R1 is put into the equation... | |
| May 4, 2018 at 19:34 | comment | added | LvW | The quantity ree=1/gm (gm: transconductance) is NOT a resistance and - in particular - not a STATIC resisistor and, therefore, must not be written as REE. It is essential in electronics to distinguish between static and dynamic resistances. | |
| May 4, 2018 at 19:32 | history | edited | Henry Crun | CC BY-SA 4.0 |
added 187 characters in body
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| May 4, 2018 at 19:26 | history | answered | Henry Crun | CC BY-SA 4.0 |