This problem studies such effects and how a Zener diode may be used to ameliorate the problem. Assume that VI=13.5V, RIN=1 kΩ, and vi=55.0mV.
how do i workout the value of vo

Question

This problem studies such effects and how a Zener diode may be used to ameliorate the problem. Assume that VI=13.5V, RIN=1 kΩ, and vi=55.0mV. 
how do i workout the value of vo

anonymous · Answer

Hi, this worked for me - vo=vin/Rin *(RD*RL)/(RD+RL)
so Try this values for both vo :    0.055/1000* (1*2000)/(2001)                So for both RL 2k and 4k you should have ~ 0.000055

anonymous · Answer

how do i work out rd sorry

nick67 · Answer

did you check here: http://openstudy.com/study#/updates/5062c622e4b0da5168bd6c57 it's quite similar

anonymous · Answer

i did but there wasnt a visible formula i could use

anonymous · Answer

RD should be 1, value taken from the graphic. Did my answers were correct?

nick67 · Answer

noise value is:
vo = vi*Rz/(Rz+Rin), where Rz is 1 Ohm

anonymous · Answer

0.000055 was right for 4k but not 2k

nick67 · Answer

the noise output with zener is quite not dependent by the load

nick67 · Answer

as far as the Rload is much higher than Zener resistance, load contribution to vo calculation is negligible

anonymous · Answer

hmmm it should be almost the same, try close values :0.000054, 0.000056 should be fine

anonymous · Answer

iv attached a print screen so you can see if i have done summit wrong

nick67 · Answer

I was talking about values with Zener in

nick67 · Answer

with RL 2K vo about 54.92 uV, with RL 4K vo about 54.93 uV

anonymous · Answer

oooohh this is the first part, where there isn't zener. The formula is a bit different here. Try these values: for 2k - 0.037 and for 4k 0.044 is it ok?

anonymous · Answer

yes you both are life savers i was stuck on this for the past 9 hours one last question is how do we work out the minimum rl

nick67 · Answer

without Zener, vo is 36.67 mV for RL = 2k and 44 mV for RL = 4K

anonymous · Answer

The formula for RL is : Vin*RL/(RL+Rin)>=5V

anonymous · Answer

Try 580-590 value, ok?

anonymous · Answer

thank you for the help mate best respone and this has probably helped alot of others that have been stuck on this one

anonymous · Answer

so it's everything ok now?

anonymous · Answer

uhhhh how did you find V0 (capital V)

anonymous · Answer

Try this if you are asking about the first part - VO=VI*RL/(RL+RIN) If not give more info what you need.