14.2. Consideration of Additional Resistor

So, let us consider the corresponding example where we can put a resistor here and instead of calling this is V; we may call it is something some other we can use different notation; let us call it is V. And, this may be whatever R and of course, that voltage it is not directly giving the voltage at this one. So, we require additional procedure to find the corresponding I current, because the V it is not giving us the V voltage.

In this chunk, we introduce a circuit where a resistor is added to the base of a BJT. The voltage applied to the base (V) is now different from the voltage across the base-emitter junction (V_BE). This implies that we need a new method to calculate the base current (I_B) because the direct voltage isn't connected to the transistor. The added resistor modifies the current flow and requires a different approach to analyze the circuit.

Think of a water pipe where you have a tap (the voltage) controlling the flow of water (current). If you suddenly put in a valve (the resistor), then the relationship between how much water flows depends not just on the tap but also on the valve's opening. This new complexity means you have to consider both components to understand the overall flow.

So, here we need to find the corresponding operating point namely I finding I, I and then V voltage and the, but then first procedure it is; the first step it is; we need to find I. So now, since as I say that since this external voltage it is not directly coming to the base ok; so, this is the equivalent model of the BJT.

To determine the operating conditions of the BJT with the added resistor, we first need to calculate the base current (I_B). Since we can't directly connect the voltage to the base, we consider the base-emitter junction as a diode and analyze the circuit as a non-linear circuit. The equivalent model is used to help incorporate the effects of the external resistor while finding the appropriate values for I_B, I_C (collector current), and V_CE (the voltage across the collector-emitter junction).

Imagine you're trying to determine how much water reaches a plant (the collector current, I_C) given that you have a tap (the base voltage) and a garden hose with a valve (the resistor). You need to find out how much water is actually available to the plant by first adjusting the valve (estimating I_B). Just as in gardening where many factors affect plant health, you must consider all components of the circuit.

And, once you get the collector current to find the V we can analyze this part and the procedure it is same as what we have just now discussed. So, compared to the previous example here the additional thing we have to do it is we have to follow some sub steps to find the corresponding base terminal current.

After calculating the collector current, we need to determine the voltage V_CE. We analyze the components of the circuit to ensure accurate calculations. The procedure requires careful consideration of how the base resistor (R_B) impacts the current flowing through the transistor. Essentially, we use KCL (Kirchhoff's Current Law) and KVL (Kirchhoff's Voltage Law) to ensure that we account for all currents and voltages in the circuit systemically.

Think of it as planning a route for multiple deliveries. Each stop (component) has its constraints (current/voltage). To ensure timely deliveries (current output), you must analyze how each section (resistor/base current) affects the overall journey (circuit output). Just as you would tweak your travel route based on traffic and delivery times, you'd adjust calculations based on circuit components.

So, either you can go through iteration; so, if you know this characteristic and then if you know the load line then you can start from this point and then whatever the for diode circuit we have discussed about iterative procedure to find the solution.

We can use an iterative approach to find the base current and consequently the collector current. This iterative method involves sketching the load line for the circuit, where the intersection of the load line with the diode characteristics helps in predicting the operating point of the BJT. The calculations might require several attempts to converge on the correct values.

Picture trying to balance a scale. You start with some weights, but it's not balanced yet. You add or remove weights (or adjust values) step by step. Similarly, in finding the base current, you make approximate calculations, check where you land on the 'balance scale', and adjust until everything levels out to the correct values in the circuit.

--