Good job!Ib = IC/gain = 21/100 = .21 mA is required to turn the transistor on
True dat. Cant have current without voltage to push the electrons through. Speaking of which let's not get into an electron flow discussion. Since your getting the Cliff Notes here we can save that topic for another Oprah show.I also recall studying that a change in the voltage V(be) causes a change in Ic. And I believe in npn transistos the current can only flow from the collector to base due to the flow of electrons
A better rule of thumb is that the base current is 10% of the collector-emitter current. Using this rule guarantees that virtually every transistor will be fully saturated.The collector current is 21 mA. This is the load consisting of one resistor and four LEDs.
We know that we need .21 mA to turn the transistor on.
Probably not what you want. As drawn, all the transistors and thus every set of LEDs is controlled by the single voltage applied to all the bases. Those switches are redundant; once any one of them is thrown, all the LEDs will light.I will look at the datasheet right now
But I was just wondering this is the visual I have right now of where we are going
Is this correct?
Wont work as drawn, but we'll get to that a bit later after you are up to speed on transistors.I will look at the datasheet right now
But I was just wondering this is the visual I have right now of where we are going
Is this correct?
OK, that's better. What I want you to take note of is that there is a range - in this case between o.65V and 0.95V. It's not a hard and fast number and is a function of collector current and base-emitter current. For design purposes I typically use 0.7 Volts.Base-Emitter Saturation Voltage (Ic=10 mA, Ib=1 mA) 0.65 V(min) 0.85V(max)
Base-Emitter Saturation Voltage (Ic=50 mA, Ib=5 mA) 0.65 V(min) 0.95V(max)
We'll get to all that as we progress. The OP is woefully lacking in fundamentals so I am deliberately taking him through this process so that he will come away with some knowledge of why as well as what. We're zipping through course material that would normally take me several weeks to cover in class and in the lab with students who are well grounded in AC & DC circuit fundamentals.A better rule of thumb is that the base current is 10% of the collector-emitter current. Using this rule guarantees that virtually every transistor will be fully saturated.
Assuming a gain of 100 is dicey, and won't always do the job.
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