Hello,

@drc_567 , Does the output only show micro volts?



Bertus

 

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Hello,

@drc_567 , Does the output only show micro volts?

View attachment 210483

Bertus

But these transistors are PNP complementary to 2N5551 I used, in the sketch they look NPN... how does this work

 

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But these transistors are PNP complementary to 2N5551 I used, in the sketch they look NPN... how does this work

NO, ITS CORRECT. COMPLEMENTARY TO 2N5551 IS 2N5401

 

2N5550 are NPNs.

Sim works without R9.

 

2N5550 are NPNs.

Sim works without R9.

can I replace the 2N5551 with S8050 is the transistors I am having at the moment

 

... so sorry ... There is an error in the SIM.
... There is some kind of problem getting the complete SIM circuit to attach to the post.
As mentioned above, the output seems to be full scale if R9 is removed.

 

can I replace the 2N5551 with S8050 is the transistors I am having at the moment

... I can't say with certainty if the S8050 transistor will function properly in the circuit.
I tried using an ordinary 2N2222_transistor and the simulation failed, so I tried the transistor shown above with some success. At the moment, I can't give a specific reason for that result.

The free LTSpice download is here:
LTSpice
Install and the ASC. file should open for use.

 

Here is the original circuit ... It has full scale output.
You need to download the LTSpice program to be able to view it.
Press the running person Icon in the toolbar to activate, and then press the Vout label on the diagram area.
A graph of the output voltage will be displayed.

 

Hello,

@drc_567 , Does the output only show micro volts?

View attachment 210483

Bertus

WHAT point in the circuit is that waveform from? I am lookingmto see the base and collector wave forms of Q2. I doubt that is what we are seeing.

 

WHAT point in the circuit is that waveform from? I am lookingmto see the base and collector wave forms of Q2. I doubt that is what we are seeing.

... If you don't have the LTSpice program, the full circuit is the same as in post #21 above, with R9 removed ... essentially producing a continuous series of constant 9 volt pulses.

 

... If you don't have the LTSpice program, the full circuit is the same as in post #21 above, with R9 removed ... essentially producing a continuous series of constant 9 volt pulses.
View attachment 210511

Show the same point with a faster sweep rate, we can see nothing useful in the display shown. the spice program will show nothing useful when it is showing so many cycles. Just two cycles showing will allow a useful image.

 

Show the same point with a faster sweep rate, we can see nothing useful in the display shown. the spice program will show nothing useful when it is showing so many cycles. Just two cycles showing will allow a useful image.

... this is a closer look.:


... one more shot:

 

If the single pulse shown is either the base or collector of transistor Q2, then there is a serious time constant problem in the multivibrator circuit with Q1 and Q2. In another version R1 and R3 were 10K ohms, the same as the base resistors.
The waveform is supposed to be ramping up and then ramping down, and that is why the performance is not as desired.

 

If the single pulse shown is either the base or collector of transistor Q2, then there is a serious time constant problem in the multivibrator circuit with Q1 and Q2. In another version R1 and R3 were 10K ohms, the same as the base resistors.
The waveform is supposed to be ramping up and then ramping down, and that is why the performance is not as desired.

... This one has diminished output amplitude.

 

OK, now at least the shape is closer to the target, but the time and amplitude are still far off. Since it is a simulation, try making R1, R2, R3, and R4 all 100K ohms. that shold make the frequency about right.

 

OK, now at least the shape is closer to the target, but the time and amplitude are still far off. Since it is a simulation, try making R1, R2, R3, and R4 all 100K ohms. that shold make the frequency about right.

.. no ... Still have diminished output amplitude.

 

Leave R1and R3 at 10K. Change R2 and R4 to 100K. Probe Q2's collector to see the On/off timing. ~10 seconds On and Off periods. Get that right first. First time using LSpice.

 

It does not seem that anything at all has changed with that large change in component values. So I am now really unsure of what point is being displayed. All I see on the circuit drawing is "Vout", which is not at all what I am asking to see.That would be a reasonable value for the voltage across R8, which I am not at all interested in seeing. When I look at te display back in post #30 I see that the pulse rate is increasing and decreasing, and so I do not believe that you are showing the voltage on the collector of Q2, but rather showing the output voltage at the collector of Q4.
Perhaps somebody else can run the simulation and display the correct point.

 

Leave R1and R3 at 10K. Change R2 and R4 to 100K. Probe Q2's collector to see the On/off timing. ~10 seconds On and Off periods. Get that right first. First time using LSpice.

Evidently the monitor point has never been set where I asked it to be set. That would explain a great deal.

 

The multivibrator on the left produces the DC voltage that slowly goes up and down and the two transistors on the right are the voltage controlled audio oscillator that slowly causes the audio frequency to go up and down.
The oscillator makes narrow pulses causing the sound to be a like a buzzer.