Timeline for npn switching an pnp with dual led
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 15, 2016 at 6:12 | comment | added | emnha | Yes, sorry my mistake. I meant both LEDs will be on. I was confused because the OP says that only one LED lights at a time. So I thought that when Vin = 0, D1 should be completely off and D2 is fully on. | |
| Oct 14, 2016 at 21:04 | comment | added | Bimpelrekkie | @anhnha You mean both LEDs will be on, true but since R3 is 10 k ohm the current through D1 will be significantly less than the current through D2 making D1 significantly less bright than D2. If that bothers you you could add a resistor in parallel with D1 to make the voltage across D1 low enough for it not to light up. | |
| Oct 14, 2016 at 13:42 | comment | added | emnha | When Vin = 0, Q1 is off but LED D1 is also on because current flows from VDD -> D1 -> R1 -> R3 -> Vbe of Q2. This will turn on Q2 and D2 is also on. So both transistors will be on? | |
| Oct 6, 2016 at 12:13 | comment | added | Bimpelrekkie | Lovely and simple as well :-) Notice how it is basically 2 times the same thing simplicity is the ultimate sophistication | |
| Oct 6, 2016 at 11:53 | comment | added | Nanchild | that really is a lovely circuit! many thanks to you both, i can now see why mine didnt work in the first place! | |
| Oct 6, 2016 at 11:52 | comment | added | Rohat Kılıç | This one is better than mine, of course. As I said before, I thought that the input has the same level as Vcc. | |
| Oct 6, 2016 at 11:51 | vote | accept | Nanchild | ||
| Oct 6, 2016 at 11:47 | comment | added | Bimpelrekkie | I can guarantee you that this one will suit you better than Rohat's one as his one is just a voltage buffer. This one has gain making it switch in a nicer way. | |
| Oct 6, 2016 at 11:45 | comment | added | Nanchild | this looks great too. will test both out. many thanks! | |
| Oct 6, 2016 at 11:43 | history | edited | Bimpelrekkie | CC BY-SA 3.0 |
edited body
|
| Oct 6, 2016 at 11:35 | vote | accept | Nanchild | ||
| Oct 6, 2016 at 11:35 | |||||
| Oct 6, 2016 at 11:31 | history | answered | Bimpelrekkie | CC BY-SA 3.0 |