Question

Summarize the principle of over-current protection observed in this experiment by answering these
questions:
4 marks

(a) Which component in the circuit of Figure 1 is the over-current sensing resistor? Use this value o
this resistor to estimate the maximum current that this circuit will output, before it shuts down

Hint For this calculation, ignore the current through the voltage divider chain and assume
a transistor turns ON when VBE 0.7V)

(b) Which component in the circuit of Figure 1 is the pass transistor?

Continue your summary of over-current protection by briefly explaining why the pass transistor
does not burn out immediately when the output is shorted lie, when R 02).

Hint

Explain what happens to Q, when Q, turns ON

(c) In the circuit of Figure 1, what component has to be changed to limit the current to a maximum
of 500 ma? What is the new value of this component?

the Be loda euprent wNEN D 3. For the circuit of Figure 1, calculate R 1 kQ. Record these calculated I values in Table B1. PROCEDURE PARTA -Series-Pass Zener-Follower Regulator Operation Q1 TIP29 R6 33R 4x 1N4006 Variac R1 2k2 R3 3k3 C1 470 uF 03 2N3904 small power transformer (nominal 28V secondary) R2 680R R4 5k RL Q2 Ds 2N3904 1N4735 R5 10k Figure 1 1. Assemble the circuit of Figure 1.

Answer 1

33..니 R, ん s more in that Case.. At even load , we design RL = 0,7 7 0.1 0.7 71 KLRmA max

Cumpnt than mx max is delivered め 7xmms ぶ Cutoe

Spom m we have maximum max max SoomA