Analyzing the circuit - Conclusion

To conclude the analysis of our circuit we are going to remember the most important things to keep in mind for our next analysis.

These are my tips!:

- Remember we are working on easy circuits, but if you will work on bigger circuits please, don´t forget use Multisim or other softwares like this. Don´t ever do it by hand.

- Remember the most always the most important ecuation of electronic, the Ohm´s Law: V = I x R

- Remember always to simplify the circuit as small as possible.

- Use the multimeter to check the values that your circuit needs. Don´t use higher voltages, currents or resistors that use all the energy.

- Remember the difference between AC - DC power. They are totally different, remember the peak-to-peak and rms values. Don´t forget the ground in AC. 
- Be sure you know the use of all components that you include in your circuit. If don´t know how to use a component read about it first. Remember also their symbols if you are going to design your circuit with Multisim.

And the end, close your circuit and have fun with the electrical energy and the electronic circuit you can build! 

 

Arturo García Pérez

Navigation Systems I – María Elena Andrés Hernández

UEM – Course 2011-2012

04/03/2012

Analyzing the circuit - Part II

Hello everybody and welcome to the last part of our electronic circuit analysis. Today we are going to perform the voltage and the current test, using Multisim 11.0 (as we show in previous chapters) and the "measurement probe function". We algo will explain how to perform it with the Ohm´s Law, but in the professional/technical world we will never perform it by hand.

Come with us to the last part of our analysis!

Voltage and current test:

As we have the value of the resistance in the important points of the circuit, and we also know the voltage of the circuit, it´s very easy to calculate the current of our circuit using the Ohm´s Law.

Remember Ohm´s Law => V = I x R

For example:

Voltage at the first parallel (P.1) of resistors: 12 Volts (12 V)
Total resistance value of the parallel (P.1) = 30/31 Ohms (30/31 Ω)
Current = ?

Then the current is:

12 = I x (30/31) -> I =  62/5 Amperes = 12.4 A

Let´s check it with Multisim 11.0:

 

And we can see that the value is correct!

Remember also that the current can take right or left direction, show the multimer + or - the value of the current. As you see in the example the current value is 12,4 A (as the Probe 1 shows) but with the multimeter we can see that the current has the opposite direction. It also has the same value but we the "-" which means that flows in the other direction (counter-clockwise).

Now we know the hand method to calculate the voltage & current value. That´s the reason I am going to show how to do it professionally, using probes at Multisim, which shows the voltage, current and frequency faster and easier.

Let´s go!

Multisim 11.0 voltage,current & frequency probes with AC Voltage:

Here, and as you know how to calculate it by hand, we are going to change the DC current (the battery) by the AC voltage. Now we can see the frequency, how the inductor acts in the circuit, the capacitors etc...

Ok, here we can see our voltage, current & frequency analisys with Multisim 11.0, let´s go to analyze it:

We can see that all the frequencies are at 25.0 kHz.
We can also see that the the I (dc) is the same in al probes, but when the inductor acts their value changes from negative to positive. However, the I (rms) and I (p-p) is the same.
Analyzing the voltages (p-p), (rms) and (dc) we can also see that they have the same values all the times, but when the voltage pass through their values changes at all, and in the last probe (probe 7) we also don´t have voltage.
Look the curious action that takes place in the probe 5, the voltage falls down to 363 V and the currents change to 2.41 mA right in possitive. At the end, at ground, obviously we don´t have voltage, that´s why the value there is 0.

Differences between "p-p" and "rms":

Surely you have noticed that the value of voltage and current is not only one, and we have peak-to-peak value (p-p) and root mean square value (rms) Ok? Yes, remember that we are working now with AC power, which means that the power doesn´t flows always in the same direction and it´s always changing. This is the reason we have p-p and rms values.

Then, the rms value is the effective value of a varying voltage or current. It is the equivalent steady DC (constant) value which gives the same effect.

For example a lamp connected to a 6V RMS AC supply will light with the same brightness when connected to a steady 6V DC supply. However, the lamp will be dimmer if connected to a 6V peak AC supply because the RMS value of this is only 4.2V (it is equivalent to a steady 4.2V DC).

- In the sinus wave-

An useful table to work with this and to change between peak values to rms values of voltage and current is:

 

Remember always also the shape of wave:

Ok, now we have finished our electronic circuit analysis!

If you want continue with the Blog let´s check it the conclusion part