Draw a schematic circuit diagram the oscillator circuit (with its differential output) that Raphael can construct using two tuned amplifiers shown above. The output of the oscillator must be clearly labelled.

Choose any 4 Questions. Where appropriate, use figures and equations to aid explanation 1.a. What are the two comparator reference voltages in a 555 timer when Vcc = 10 V? 1.b. Determine the frequency of oscillation for the 555 astable oscillators in Figure. 1.c. To what value must Cext be changed to achieve a frequency of 25 kHz? +5.5 V 1.0 kn R₂ • 3.3 ΚΩ Cest 0.047μF RESET DISCH THRESH TRIG 555 GND Vec OUT CONT C₁ 0.01 F 1.d. In an astable 555 configuration, the external resistor R1 = 3.3 k. What must R2 equal to produce a duty cycle of 75%.