circuits. help please.

Question

zephyr141 · Answer

Determine the value of Vout for circuits a and b.|dw:1441074230030:dw||dw:1441074398505:dw|

zephyr141 · Answer

i'm a little stuck here. i kind of blanked on how to start...

zephyr141 · Answer

so i know that a Si diode has a 0.7 V drop and a Ge diode has a 0.3V drop. so i'm confused as to what happens afterwards. at the 2kOhm resistor.

kenljw · Answer

Can't do the first for lack of input
Assuming Si on voltage or .7 volts
ID = (10 - .7)/(1.2 +4.7) mA = 1.58 mA
If this is sufficient for ID on then
Vo = 1.58X4.7 V = 7.45 V

zephyr141 · Answer

whoops. the first one has an input of 12V

zephyr141 · Answer

so then Vo for the first one would end up being about 9.2V?

kenljw · Answer

Yes, apparantly you got the idea, more accuarate analysis would entail using the Ideal diode with the specification of diode.  Could be tricky but necessary if one is to have a signal input as well as DC, you will need to fine the diode signal resistance.  This is used as a demodulator ciruit generally for Ampitude Modulation, AM