Timeline for Zener diode + transistor circuit
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 21, 2022 at 22:25 | vote | accept | Domingo | ||
| Oct 4, 2021 at 20:12 | comment | added | Theodore | Here is another question about a circuit with a similar function: electronics.stackexchange.com/questions/547417/… | |
| Oct 4, 2021 at 19:39 | answer | added | jonk | timeline score: 6 | |
| Oct 4, 2021 at 19:24 | comment | added | Domingo | Thank you Bimpelrekkie, I'll try to think that way and now I understand actually why the zener was not cutting at 10v exactly but almost 11v. Appreciated. But still, given the case of a diode with a 3.3k resistor (per schematic), how can you know the appropriate base (zener) resistor value for it? So no power is dissipated and the same power arrives to the led? I figured it out at 11k trying different values with a potentiometer, but how can one know in advance? @TimWescott I meant the zener diode resistor (see diagram). | |
| Oct 4, 2021 at 19:05 | comment | added | Bimpelrekkie | This circuit will turn the LED on when the supply reaches around 10.6 V (10 V zener diode + Vbe of the transistor). I don't know why and couldn't find a formula that explains my result Circuits aren't defined by formulas. You need to think in terms of: when the voltage reaches 10 V, can the zener diode conduct? No because there's also a Vbe of the PNP. Only when that Vbe is larger than 0.6 V will any current flow through the Emitter-Base. What will happen when when current flows through the Emitter-Base of the PNP? Again: no formulas! | |
| Oct 4, 2021 at 18:47 | comment | added | TimWescott | When you say "diode resistor" do you mean the zener diode resistor? An LED is also a diode. | |
| Oct 4, 2021 at 18:43 | history | edited | JRE | CC BY-SA 4.0 |
added 12 characters in body
|
| S Oct 4, 2021 at 18:35 | review | First questions | |||
| Oct 4, 2021 at 18:40 | |||||
| S Oct 4, 2021 at 18:35 | history | asked | Domingo | CC BY-SA 4.0 |