5.1 State ONE effect of switch bounce in electronic circuits - NSC Electrical Technology Electronics - Question 5 - 2024 - Paper 1

Feedback in this circuit refers to a portion of the output voltage being fed back to the non-inverting input via the voltage divider formed by resistors R2 and R3. This ensures that the circuit maintains its state by comparing the input voltage against this feedback voltage.

When a positive trigger pulse is applied, the capacitor C1 charges immediately to the applied voltage. This rapid charging influences the state of the op-amp, ultimately determining the output voltage level.

Upon receiving a negative trigger pulse, the op-amp compares the voltage levels at both of its inputs. If the voltage at the inverting input exceeds that at the non-inverting input, the output will transition to its low state, depending on the current configuration of feedback and input voltages.

The output does not change when trigger pulse 2 is applied if the voltage on the non-inverting input remains higher than the voltage on the inverting input, which keeps the circuit in its current state.

The circuit depicted in FIGURE 5.3 is a monostable multivibrator.

Resistor R2 keeps pin 2 of the monostable circuit in its steady state by providing a defined reference voltage, which influences the timing and response of the circuit.

The output waveform should reflect a single pulse corresponding to the duration defined by the timing components of the circuit when it receives a trigger signal.

The voltage at which the circuit will reset to its resting state is 6 V because the voltage across the timing capacitor must charge up to two-thirds of the supply voltage before the output can return to its dormant state.

The output changes state continuously because both trigger pin 2 and threshold pin 6 are wired to the timing capacitor. As the capacitor charges and discharges, it causes the circuit to repeatedly reset and trigger, resulting in a continuous stream of high and low outputs.

t1 and t2 are not equal because the capacitor charges through R1 but discharges through R2, causing differences in duration for the charging and discharging phases due to differing resistances.

The frequency of the output can be calculated using the formula: f = rac{1}{T}, where T is the total period. For the given values, substituting leads to a frequency of approximately 7.18 Hz.

The reference voltage can be determined by the voltage divider formed; it is calculated to be 4.5 V.

The resistance of R1 is significantly impacted by the feedback operation. Increasing its value will increase the voltage across R2, while maintaining the reference conditions of the comparator when applied.

The output voltage will switch between +9 V and -9 V depending on whether the input voltage exceeds or falls below the reference voltage.

An increase in the value of R1 will mean that R1 > R2, resulting in a reduced voltage across R2 because the effective resistance seen by the voltage divider lowers the voltage drop across R2.

A summing amplifier allows multiple input voltages to be combined and produces a single output voltage that represents the sum of its inputs, facilitating additive signal processing.

Using the formula: V_{out} = -rac{R_f}{R_1} V_1 - rac{R_f}{R_2} V_2 - rac{R_f}{R_3} V_3 Substituting leads to: V_{out} = -rac{33000}{2200} (0.1) - rac{33000}{2200} (0.2) - rac{33000}{2200} (0.3) o V_{out} = -9 ext{V}.

When Rf is set to 220 Ω, the gain of the amplifier becomes 1, meaning the output voltage becomes equal to the sum of the input voltages, limited under the given conditions.

The output should display a waveform that shows the charging and discharging of the capacitor corresponding to the input square wave.

During the first positive square wave, both plates of the capacitor quickly charge to the potential of the input, maintaining that voltage as long as the input remains high.

To convert the circuit to a passive integrator, you would replace the capacitor with a resistor in series with the input signal and adjust the feedback loop accordingly, allowing for integral behavior of the input waveforms.