Cant seem to figure this problem out

Thread Starter

suushi

Joined Apr 26, 2017
11
Stuck on the first part. I understand that if its a 0 there will be no output signal and if there is a 1 there will be one but not sure how the mosfet will affect the output at both TPA and TPB.
At H(4) the out put will be a NAND'd TPA and TPB.
Any help would be appreciated
 

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#12

Joined Nov 30, 2010
18,223
There are no mosfets in your drawing.
You could google, "common emitter" or , "common emitter amplifier" to see what happens.
 

Thread Starter

suushi

Joined Apr 26, 2017
11
You're right. Transistor* So, it should amply the signal when passed through. The signal should be the same but amplified.
 

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Thread Starter

suushi

Joined Apr 26, 2017
11
Ok. This is my attempt at the problem. It seems like S0(1) is a NAND of TPA. And for S0(3) i tried to NAND TPA and TPB as best I could. However if I was wrong about the transistor just amplify the signal then the rest would be incorrect.
 

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WBahn

Joined Mar 31, 2012
26,398
Stuck on the first part. I understand that if its a 0 there will be no output signal and if there is a 1 there will be one but not sure how the mosfet will affect the output at both TPA and TPB.
At H(4) the out put will be a NAND'd TPA and TPB.
Any help would be appreciated
How can the signal at H(4) be affected by TPA?
 

WBahn

Joined Mar 31, 2012
26,398
Stuck on the first part. I understand that if its a 0 there will be no output signal and if there is a 1 there will be one but not sure how the mosfet will affect the output at both TPA and TPB.
At H(4) the out put will be a NAND'd TPA and TPB.
Any help would be appreciated
The transistor appears to be intended to act as a switch; it depends on the exact input voltage, but the implication is that the inputs are either HI (something close to 5 V) or LO (something close to 0 V).
 

dl324

Joined Mar 30, 2015
13,820
However if I was wrong about the transistor just amplify the signal then the rest would be incorrect.
Do the TPA or TPB signals look correct?

Take a look at the simpler case for TPB. When G is 5V, what is the voltage on the collector of that transistor?
 

WBahn

Joined Mar 31, 2012
26,398
I dont think it would affect the problem.
Why not? What if it is a 464 V battery? That would sure affect the problem!

It's a very fair question, but in the face of no answer, we have to either declare the problem unsolvable or make reasonable assumptions, such as that it is a resistor of an appropriate size so that the circuit behaves the way we expect it to behave. Not the best way to go, but sometimes ya gotta do what ya gotta do.
 

Thread Starter

suushi

Joined Apr 26, 2017
11
Do the TPA or TPB signals look correct?

Take a look at the simpler case for TPB. When G is 5V, what is the voltage on the collector of that transistor?
I've reworked tpa and tpb, and the rest of the problem. I think the signal 5 and 6 at tpa and tpb are just delayed
 

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WBahn

Joined Mar 31, 2012
26,398
If SIG is LO, what is TPA?

If SIG is HI, what is TPA?

Don't handwave it. If SIG is LO, is the transistor switch open or closed? If the transistor switch is open, what is TPA? If the transistor switch is closed, what is TPA?
 

dl324

Joined Mar 30, 2015
13,820
I've reworked tpa and tpb, and the rest of the problem. I think the signal 5 and 6 at tpa and tpb are just delayed
That isn't what you drew. What is the relationship between signals SIG and TPA?

It would be helpful if you used more appropriate image sizes. Cropped image:
upload_2017-4-26_14-44-47.png
 

Thread Starter

suushi

Joined Apr 26, 2017
11
If SIG is LO, what is TPA?

If SIG is HI, what is TPA?

Don't handwave it. If SIG is LO, is the transistor switch open or closed? If the transistor switch is open, what is TPA? If the transistor switch is closed, what is TPA?
If sig is low it would be 0 or off if sig is HI tpa would be same as SIG
 

WBahn

Joined Mar 31, 2012
26,398
So if SIG is LO and the transistor switch is OFF (open), you have TPA tied to 5 V through a resistor that has no current flowing in it. Is TPA at a high voltage or a low voltage?
 
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