| Electronics > Beginners |
| Transistor Switching |
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| Zero999:
I've done some simulations and have tweaked the values a bit. In my previous circuit, I overestimated the forward voltage of the diodes, so reduced the emitter resistor and increased the current through them, so it gives roughly 20mA through the LED. The potentiometer is modelled as two resistors: VR1_A and VR2_B: the former is swept from 1R to just over 10k and the latter from 10k to 1R, to simulate the pot wiper being adjusted. V2 represents the LED's forward voltage drop. It's swept from 0V to 8.5V in 1V increments. Notice there's hardly any change in current between 0V and 8V and it only drops, when the forward voltage goes past 8.5V and the drop is only significant at higher current settings. |
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