Hello, can somebody help wich transistor is like bfg520

[michael1978]

LTSPICE uses a version of Spice so will probably work.
I use Simetrix Elements which is the best simulator I have ever come across. The BF199 is in my model data base. Simetrix Elements is free to down load but has a limitation on the number of nodes. That has only ever been a limiting factor on very large sim's that I have tried.

I wis use but i am not sure anymore did i make a circuit without mistake, because in picture on document where found , it was no good picture

 

[michael1978]

LTSPICE uses a version of Spice so will probably work.
I use Simetrix Elements which is the best simulator I have ever come across. The BF199 is in my model data base. Simetrix Elements is free to down load but has a limitation on the number of nodes. That has only ever been a limiting factor on very large sim's that I have tried.

Can you look maybe my oscillator os if its correct i go to download the software

 

[Audioguru]

My 88MHz to 108MHz FM transmitter and many others use an ordinary common 2N3904 transistor as its RF oscillator transistor.

 

[michael1978]

My 88MHz to 108MHz FM transmitter and many others use an ordinary common 2N3904 transistor as its RF oscillator transistor.

oooo AudiGuru, you make to smile, i ask for my, did i make mistake of where haha
i take it from here, if you can help me

 

[Audioguru]

Your inductor is series resonant but I think it should be parallel resonant like this:

 

[michael1978]

Your inductor is series resonant but I think it should be parallel resonant like this:

thnx Audioguruu, one more question, is varactor diode to tune the frequency, why he does not change the frequency

 

[Audioguru]

You cannot tune your oscillator because it is completely wrong.
Why can't you see and understand the differences?

 

[michael1978]

You cannot tune your oscillator because it is completely wrong.
Why can't you see and understand the differences?

I change but i dont know wich value to put to cc and co

 

[Audioguru]

What do you think is the function of cc and co? Don't you think they must pass signals from 88MHz to 108MHz?
Then make their values 220pF.
I notice that your capacitor between the base and emitter of the first transistor is extremely high at 220μF which will not pass the VHF signal. Use 220pF instead.

 

[michael1978]

What do you think is the function of cc and co? Don't you think they must pass signals from 88MHz to 108MHz?
Then make their values 220pF.
I notice that your capacitor between the base and emitter of the first transistor is extremely high at 220μF which will not pass the VHF signal. Use 220pF instead.

Like i understand in book, they must pass 88 to 108Mhz, that the purpose of this circuits, is special for fm SUPERHETERO tuner

 

[michael1978]

For 100MHz you could try a BF199, which is a common one.

Bob

Bob i wil like to ask you did i make mistake in circuits wich i buid it

 

[michael1978]

What do you think is the function of cc and co? Don't you think they must pass signals from 88MHz to 108MHz?
Then make their values 220pF.
I notice that your capacitor between the base and emitter of the first transistor is extremely high at 220μF which will not pass the VHF signal. Use 220pF instead.

Audioguru are you here somewhere

 

[Audioguru]

Before I wrongly guessed that you are making an FM transmitter. But now I see that you are simulating the oscillator of an FM superheterodyne radio.

 

[michael1978]

Before I wrongly guessed that you are making an FM transmitter. But now I see that you are simulating the oscillator of an FM superheterodyne radio.

No No i can give the site where i take it, but is not working

 

[michael1978]

If your Multisim uses the spice platform, Try the model below.
You should be able to copy and paste into you program!

From: C:\Program Files (x86)\SIMetrix-SIMPLIS Elements_810\support\Models\bipolar.lb, line 143



*From Philips SC04 "Small signal transistors 1991" and NS Discrete 1978

* Base resistance not modelled - no info. CBE estimated. Vce(sat) estimated.

.model BF199 npn ( IS=1.61E-15 VAF=35.8 BF=150 IKF=0.0467 NE=1.3552

+ ISE=1.494E-14 IKR=0.001 ISC=1.00E-14 NC=1.5 NR=1 BR=5 RC=10 CJC=5.00E-13

+ FC=0.5 MJC=0.2 VJC=0.8 CJE=5.00E-12 MJE=0.4 VJE=0.6 TF=1.86E-10

+ ITF=0.045 VTF=3 XTF=50 RE=1)

Sir are you here i download the software and i build circuit, but is not working maybe you have more experience with that software

 

[WHONOES]

What software have you downloaded. Which circuit have you built / modelled? You need to be more explicit.

 

[michael1978]

What software have you downloaded. Which circuit have you built / modelled? You need to be more explicit.

Hello, this simetrix element, and i build the circuits but i get error dcop(error) i cant simulate, if you want i can send you my file to you, everything is build just to test to simulate

 

[WHONOES]

Hello, this simetrix element, and i build the circuits but i get error dcop(error) i cant simulate, if you want i can send you my file to you, everything is build just to test to simulate

I still don't know which circuit you have modelled.

 

[michael1978]

I still don't know which circuit you have modelled.

LOCAL OSCILLATOR

 

[Audioguru]

It will not work. I told you and showed you:
1) L1 must be parallel with its tuning varactor but instead it is wrongly in series with it.
2) The value of C1 is 1 million times too much at 220uF and instead should be 220pF.