Good morning, I have schema ( picture ), but I don't know how to created it on NI Multisim ( I do it, but this schema looks like... You can see in my attached files ).
I must have and component who can show me the oscilograms. How should I do it ?
And one more problem: I don't find component - VT2, VT3 and VT4 ( in picture ) in NI Mulstisim ( 13 ) program.



Thank You!

 

What is the source of your schematic picture? It looks like you drew it in mspaint. Are you not showing all the information available to you?

VTx where x is a number is the component designation. Multisim identifies transistors differently. Cx would be capacitor, Rx would be resistor, Qx or Tx or in the case of your picture, VTx is transistors. Lx is inductors. Of course the V could mean Virtual ... or perfect. VD1 is a diode.

You can insert some NPN and PNP transistors as appropriate to make the schematic in multisim.

 

What is the source of your schematic picture? It looks like you drew it in mspaint. Are you not showing all the information available to you?

VTx where x is a number is the component designation. Multisim identifies transistors differently. Cx would be capacitor, Rx would be resistor, Qx or Tx or in the case of your picture, VTx is transistors. Lx is inductors. Of course the V could mean Virtual ... or perfect. VD1 is a diode.

You can insert some NPN and PNP transistors as appropriate to make the schematic in multisim.

Yea, I drew it on windows paint. I have just these numbers of it:

P(out)= 2W
R(load/strain/workload) = 12Ω
Uin = 20mV
F = 300 Hz to 7 kHz
Rin = 2 kΩ
M <= 3dB
And I have created audio amplifier.

I attachement better schema of it.

But I have problem:

I add 20mV ( I try and 20, 100 V ) in AC voltage, but osicilograms showing something wrong.. I attachement some picture of it.
What can be problem at ?

 

One error I see is no connection dot between bias resistors R3, R4, and Q1's base, thus Q1 has no bias.

 

One error I see is no connection dot between bias resistors R3, R4, and Q1's base, thus Q1 has no bias.

Thank You! But right now I got still bad simulated. What it's could be wrong ?

 

You have your input at 100 volts peak.....what is it suppose to be?

Your Vcc is only 15 volts dc.

 

You have your input at 100 volts peak.....what is it suppose to be?

Your Vcc is only 15 volts dc.

He tried with different voltages 100V, 20V and 20mV, but the 100V is really crazy for a input, since the input never great than 2V.

 

I can change voltages to 2V or smth else, but oscilograms showing no sinusoid. What should I do ? Maybe my schema is wrong ?

 

The value of resistors quite strange, you could change the position first,.
1. Cut off the connection from R5 and C4.
2. Connecting R5 to GND.
3. Connecting C4 to the e of Q1.
And try again, when it can do the amplifying then you can adjust the value of resistors.

 

The value of resistors quite strange, you could change the position first,.
1. Cut off the connection from R5 and C4.
2. Connecting R5 to GND.
3. Connecting C4 to the e of Q1.
And try again, when it can do the amplifying then you can adjust the value of resistors.

I do it. I attachment picture. But I see what C4 ir going/flashing to red color.
And oscilograms showing still not really sinusoid.
P.S. What wrong with resistors position ?

 

Hello,

during the move of the capacitor, you have made a break in one of the nets:

Bertus

 

Hello,

during the move of the capacitor, you have made a break in one of the nets:

Bertus

I understand clearly, I have to do this ?

 

Check this file

 

The negative of C4 and the c of Q2, R4 and 0V of input signal, they must be connecting to GND, I 'm sure why you disconnected them?

And set the Vin max to 2V.

 

Hello,

No, the cap would short the input signal.
Here I corrected the circuit in paint:

Bertus

 

No way, the correct circuit should look like this

 

No way, the correct circuit should look like this
View attachment 78987

The problem of R5 and C5 as I mentioned on #9, do you think is it ok?

 

Hello Jony,

I was just following the instructions of ScottWang in post #9.

Bertus

 

The problem of R5 and C5 as I mentioned on #9, do you think is it ok?

R5 and C5 should be connected in series.
Because this circuit should work as a poor's man op amp. And Q1 is a differential amplifier (base a "+" input and emitter as a"-" input) and the closed loop gain is equally to
Av =(1+ R6/R5) ≈ R6/R5

Here you have a very similar circuit

 

R5 and C5 should be connected in series.
Because this circuit should work as a poor's man op amp. And Q1 is a differential amplifier (base a "+" input and emitter as a"-" input) and the closed loop gain is equally to
Av =(1+ R6/R5) ≈ R6/R5

Here you have a very similar circuit

No, they are different, in your new circuit that the R4 and C3 is in parallel with the Vce, and the c of 3906 has 8.2k to provide the dc quiescent current to ground, the R3(2.7K) provide the feedback current.

The circuit of bertus on #15, R6 is the feedback current, R5 provide the dc quiescent current to ground, you can't using the feedback resistor to replace the e resistor, if you do that then the e will loss the dc quiescent current.