Timeline for Why does capacitive coupling require a base resistor in an emitter follower?
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 6 at 11:30 | comment | added | Russell McMahon♦ | WARNING You probably realise already, but it's crucial that you do, that the environments shown are almost "articial" as they show a -Vee DC supply . This is entirely reasonable in giving examples but in probably the majority of situations you'll encounter, Re is ground referenced and in such cases both circuits will clip the output when Vin falls below about 0.6V wrt ground - as per Simon's last graph. || If that was already wholly obvious then nothing to see here, move along :-). |||| The base needs a DC reference point that an AC Vin will vary about. The capacitor removes it. Rb re-adds it | |
| Jan 5 at 6:09 | answer | added | Simon Fitch | timeline score: 2 | |
| Jan 5 at 1:32 | history | became hot network question | |||
| Jan 5 at 0:38 | comment | added | TimWescott | Get a spice program (LTSpice is nice), and simulate 2.17 with and without \$R_B\$. See what happens -- then use that to figure out why you need \$R_B\$. If you get stuck, put an ammeter on the base of the transistor. | |
| Jan 4 at 22:35 | answer | added | Circuit fantasist | timeline score: 2 | |
| Jan 4 at 19:19 | history | edited | JRE | CC BY-SA 4.0 | added 8 characters in body; edited title |
| Jan 4 at 18:56 | history | edited | nuggethead | CC BY-SA 4.0 | added 75 characters in body |
| Jan 4 at 18:43 | answer | added | Michal Podmanický | timeline score: 8 | |
| Jan 4 at 17:37 | answer | added | Tyassin | timeline score: 4 | |
| Jan 4 at 17:25 | history | asked | nuggethead | CC BY-SA 4.0 |