# Electronics 101 HELP

Discussion in 'Homework Help' started by Sberndt6853, Nov 8, 2014.

1. ### Sberndt6853 Thread Starter New Member

Nov 8, 2014
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ALL RESISTORS ARE 1K OHMS
This is my readings with my meter now I need to use Ohm's law and Kirchhoff's laws(current and voltage) to go along with the readings.
Thanks

Last edited by a moderator: Nov 9, 2014
2. ### joeyd999 AAC Fanatic!

Jun 6, 2011
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We'd be happy to critique your analysis.

3. ### WBahn Moderator

Mar 31, 2012
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When you say that these are your readings with your meter, how were the measurements made and what kind of meter? In particular, how are you getting your current measurements?

What is the other side of your 10V source connected to? Ground? If so, consider the voltage across R5; how could it possibly be just 5V.

You also need to indicate the polarity of the voltages and/or currents in each resistor.

4. ### Sberndt6853 Thread Starter New Member

Nov 8, 2014
11
0
It is +5 on one side and -5 on the other

Last edited by a moderator: Nov 9, 2014

Feb 19, 2010
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How much?

6. ### WBahn Moderator

Mar 31, 2012
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You need to be much more explicit and descriptive. What do you mean when you say that it is -5 on the other? You have no negative supply, so it is -5 V relative to what?

If it was +5V on one side and -5V on the other side, then that is 10V across the resistor, not 5V as indicated in your diagram.

How you make a measurement is important because making a measurement always affects the measurement being made. What you make the measurement with is important because that determines how much of an effect you have on the measurement.

So please describe how you obtained your voltage and current measurements and what you used to make them. In particular, was it a digital VOM meter or an analog VOM meter? Did you get your current measurements by breaking the connection in one branch and inserting the current meter in series with it?

7. ### Sberndt6853 Thread Starter New Member

Nov 8, 2014
11
0
Ok I will redo my schematic to show the ground being -5 but I thought it did not matter.

Maybe that is why the math is nt working because I only am running 5 volts through the circuit

It is a digital multimeter of lower quality. My power source is the Analog Discovery by Digilent

Ok I set up my Analog Discovery wrong. Starting all over thanks for the input.

ALL RESISTORS ARE 1K OHMS
This is my readings with my meter now I need to use Ohm's law and Kirchhoff's laws(current and voltage) to go along with the readings. My power sources is the Analog Discovery by Digilent and is +5volts on one side and -5volts on the other. It looks like both are positive but if one looks close it is negative. Resistor 5 I am not sure about the amps because the analog discovery shuts down when I take a reading. I just need tobe able to explain with the math only. That is where I am struggling.

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• ###### Spencer-Berndt (4).pdf
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Last edited by a moderator: Nov 9, 2014
8. ### WBahn Moderator

Mar 31, 2012
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Notice that your currents (I'm having to do some guessing since you give no indication of polarities) add up to 7.2 mA (1.4 mA + 5.8 mA) compared to the 6.7 mA you are claiming to have measured in R6.

The fact that your voltages are coming out to be exactly integer values is highly suspicious. I think you are not measuring to the resolution that you need.

And again, how are you taking your current measurements? What is the series resistance of your meter? Have you checked the accuracy of your meter against anything?

Nov 8, 2014
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10. ### WBahn Moderator

Mar 31, 2012
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Why do you keep posting the same (or nearly the same) diagram instead of answering a very simple question.

For the final time, before I move on to someone that is willing to cooperate, when you say that the current in, say, R6 is 6.7mA, what exactly are the steps that you took to come up with that value?

11. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
Why are you starting another thread on the same problem?

The fact that your system is shutting down when you try to take a reading is a very strong sign that you are not taking your readings correctly. But you refuse to explain how you are taking your readings, so it is virtually impossible to help you.

12. ### JoeJester AAC Fanatic!

Apr 26, 2005
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I've yet to see a complete circuit from them. The two 5V sources had only ONE connection each to the circuit.

13. ### JoeJester AAC Fanatic!

Apr 26, 2005
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This is a duplicate thread. I'll be recommending to the moderators to close this one.

14. ### Sberndt6853 Thread Starter New Member

Nov 8, 2014
11
0
So R5 has to be 10V 1A and 1000 OHMS
I am using a cheap digital multimeter and a portable analog circuit design kit from Digilent. R1,2,3,6(the volts and amps and not sure about ohms) needs to equal R5 which than needs to equal R10,9,8,6, and visually I can see but proving it with the different laws is where I am struggling.

15. ### shteii01 AAC Fanatic!

Feb 19, 2010
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The resistor value should be marked on it using color code.

This way all you need to do is measure the voltage. Then you have the resistor and voltage across that resistor, and you can calculate currenth through the resistor. No need to eF up with measuring current.

16. ### WBahn Moderator

Mar 31, 2012
18,087
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I'm pretty sure that the unconnected side of each source is the common for the Analog Discovery. Basically the +5V and -5V supplies from the Analog Discovery are connected to the two sides of R5.

17. ### WBahn Moderator

Mar 31, 2012
18,087
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You are making less and less sense all the time. All of your diagrams up to this point have stated very explicitly that all of the resistors were 1 kΩ, but now you are saying that you aren't sure what they are.

And you still haven't describe HOW you came up with the values for the current that you have in your diagram. What is SO HARD about describing what you did to make those measurements?

What, exactly, did you do to make your current measure for R5. How can we possibly tell you what you might be doing wrong if you won't tell us what you did?!

18. ### shteii01 AAC Fanatic!

Feb 19, 2010
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It is actually pretty hard if you are not a native English speaker or just plain lazy. I out to know since I have a bit of both. ☺

Apr 5, 2008
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Hello,

I merged the threads and merged subsequent posts of the OP.

Bertus

20. ### JoeJester AAC Fanatic!

Apr 26, 2005
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The OP opened his statement with "ALL RESISTORS ARE 1k."

The OP's diagram does not reflect that tidbit of information.

Does the OP know ohms law? 1 volt across a 1kΩ resistor does not equal 1.4 mA. Did the OP measure the current? I doubt it.

Granted, there is a tolerance in real life. Did the OP measure the resistances before constructing the circuit? The information is scare.

I'm sure the OP's lab assignment had specific criteria. He did not share anything other than his diagram.

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