# diode circuit

#### ramphisaj

Joined Oct 18, 2006
7
i need help please see attachment.

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#### hgmjr

Joined Jan 28, 2005
9,029
Is it possible that each of of the two circuits in question have a resistor between the junction of the diodes and the positive supply input?

If not, then the circuits as drawn, while doable, are not very realistic.

There is bound to be a diode or diodes destroyed in the circuits as drawn.

hgmjr

#### nomurphy

Joined Aug 8, 2005
567
IF you have rendered the schematics for this problem correctly, then I feel sorry for you, because it is a foolish scenario/question.

Assuming the diodes could somehow handle the current due to the voltage potentials, the answers are:
1) +5V
2) +15V

Because Vout is tied directly to the supply voltage(s) -- especially after the diodes burn up.

#### Johann

Joined Nov 27, 2006
190
I think your circuit needs a resistor between +5V and output. Then (and only then), this represents some form of diode logic circuit. In the first circuit (if a resistor is inserted between +5V and out), and assuming a volt drop of 0,7 volts per diode, the two diodes with +5V inputs will not be biassed at all and will have no effect, however, the two diodes with the -5V inputs will be forward biased. The output will then be 0,7V higher than the -5V, i.e. -4,3V.