Further Electronics

[DuBistKomisch]

I know Further Electronics is the least common detailed study, but surely I wasn't the only one who thought it was particularly tricky on this exam.

My answers:
1. C (3600 × 12/240 = 180)
2. B
3. B (12 - 2 × 0.7 = 10.6 V)
4. C (7 cm × 2 V/cm = 14 V)
5. A (T = 4 cm × 20 ms/cm = 80 ms; f = 1/0.08 = 12.5 Hz)
6. C (C = t/R = 0.01/100 = 100 µF)
7. C (I = V/R = 9.5/100 = 95 mA)
8. C (going from graph on previous page)
9. C (smaller R -> larger ripple; same peak)
10. A
11. C (5 V × 0.02 A = 0.1W)
12. B

I reckon I got at least question 10 wrong. What about you guys?

[kenhung123]

Was 10 the one asking about ripple with input changes?
11 I got 6*0.02=0.12W

[DuBistKomisch]

Yeah, question 10 was changing the output of the transformer and hence diode bridge from 12V to 20V.

11 I took the average voltage to be 5V (varied between 4 and 6 about evenly).

[kenhung123]

Zener voltage was 6 though.

10, I'm not too sure. Is the smoothing affected by input voltage? All I know is zener maintains the voltage about 6V (in this case)

[DuBistKomisch]

The graph of the CRO output showed the voltage changing between 4 and 6 volts.
For 10 I really don't think I got right, C was probably the correct one with the same peak voltage and ripple voltage. :-/
The questions are available here: http://vcenotes.com/forum/index.php/topic,26634.msg270684.html#msg270684.

[DuBistKomisch]

Besides, 0.12W wasn't an option...

[kenhung123]

ACtually I put 0.1 since I rounded down..what you get for 8?

[ks04]

1. C
2. B
3. B
4. C
5. A
6. C
7. C
8. D (was tossing between C & D)
9. C
10 B (wasn't too sure here)
11 C
12 D (now see this should be b :\)
were mine...

[DuBistKomisch]

8 I wasn't too sure for either. :-/
At first I thought D from calculating the ripple voltage, but that didn't add up with the discharging graph on the previous page, so I went with C.

[dyaner]

One of the questions was messed up!
Two options for Q10 (I think) were the same.

[ks04]

One of the questions was messed up!
Two options for Q10 (I think) were the same.

Yea this got announced to us at the start of the exam, of course i was the only one doing futher electronics too!

[dyaner]

One of the questions was messed up!
Two options for Q10 (I think) were the same.

Yea this got announced to us at the start of the exam, of course i was the only one doing futher electronics too!

I was so annoyed so I randomly chose A to get overdone with, and it was one of the exactly same options though D was disregarded. Options B and D looked stupid... Or maybe I am one. Hahaha.