Hello, can somebody check my transistor amplifier schematic?

[Baluncore]

We have a problem arising here because some component identifications has been changed by michael1978 in the latest diagrams. That needs to be fixed or it will lead to confusion.

I have usually found that the fewer components in the oscillator circuit the better, and I especially do not like the use of a resistor in the emitter of Q1 as it is shunting the tuned circuit. I have found the Hartley circuit to require fewest components and be the most reliable.

Different oscillators have different features. If adding a couple of components reduces harmonics by another 10dB then there will be applications where a higher component count can be an advantage. Reduced component count reduces costs in consumer equipment. It also reduces quality.

The problem with amplifier design is using feedback to advantage, while avoiding self oscillation. I see all named oscillators as being a rogues gallery of failed amplifier designers.

The oscillator being modeled here with the LPF to remove harmonics is a bit confusing. That is because the input and output impedance of the LPF module is not specified and so internal reflections from that LPF occur. I think that LPF is a liability.

 

[michael1978]

We have a problem arising here because some component identifications has been changed by michael1978 in the latest diagrams. That needs to be fixed or it will lead to confusion.Different oscillators have different features. If adding a couple of components reduces harmonics by another 10dB then there will be applications where a higher component count can be an advantage. Reduced component count reduces costs in consumer equipment. It also reduces quality.

The problem with amplifier design is using feedback to advantage, while avoiding self oscillation. I see all named oscillators as being a rogues gallery of failed amplifier designers.

The oscillator being modeled here with the LPF to remove harmonics is a bit confusing. That is because the input and output impedance of the LPF module is not specified and so internal reflections from that LPF occur. I think that LPF is a liability.

this is 150u

i don't understand, when i zoom is bad waveform, what to do next, what to do with lpf, you know, why i told about this simetrix, somebody told me is the best simulator, for that i said to you

 

[michael1978]

this is 150uView attachment 228718
i don't understand, when i zoom is bad waveform, what to do next, what to do with lpf, you know, why i told about this simetrix, somebody told me is the best simulator, for that i said to you

I don't understand also when i make 5u is good sinewave if it goes more is bad sinewave

 

[michael1978]

We have a problem arising here because some component identifications has been changed by michael1978 in the latest diagrams. That needs to be fixed or it will lead to confusion.Different oscillators have different features. If adding a couple of components reduces harmonics by another 10dB then there will be applications where a higher component count can be an advantage. Reduced component count reduces costs in consumer equipment. It also reduces quality.

The problem with amplifier design is using feedback to advantage, while avoiding self oscillation. I see all named oscillators as being a rogues gallery of failed amplifier designers.

The oscillator being modeled here with the LPF to remove harmonics is a bit confusing. That is because the input and output impedance of the LPF module is not specified and so internal reflections from that LPF occur. I think that LPF is a liability.

Hey my dear i fix it, somebody told me, i just change The R4 to 360 and is working THANK YOU A LOTTTT;;;...… SO THAT I MAKE TIRED. THANKS

 

[michael1978]

We have a problem arising here because some component identifications has been changed by michael1978 in the latest diagrams. That needs to be fixed or it will lead to confusion.Different oscillators have different features. If adding a couple of components reduces harmonics by another 10dB then there will be applications where a higher component count can be an advantage. Reduced component count reduces costs in consumer equipment. It also reduces quality.

The problem with amplifier design is using feedback to advantage, while avoiding self oscillation. I see all named oscillators as being a rogues gallery of failed amplifier designers.

The oscillator being modeled here with the LPF to remove harmonics is a bit confusing. That is because the input and output impedance of the LPF module is not specified and so internal reflections from that LPF occur. I think that LPF is a liability.

Sorry sir i wil like to ask the last one i think, everything was okej yesterday with sinewaveform, but today i connect the varicap and i start to get bad sinewave?
what do you think?

 

[Baluncore]

You must use the correct spice varicap model and parameters. I do not know which spice model varicap you are using.

You know the low and high frequency ends of the FM band. The Local Oscillator frequency range needed is offset by the IF frequency. You can calculate or simulate the capacitance needed to maintain oscillation at the ends of the band. Select from manufacturers data an available real varicap that provides the required variation in capacitance. Find or make a spice model of that varicap.

The BBY40 was originally used. I google 'BBY40 spice model' and find;
http://www.gunthard-kraus.de/Spice_Model_CD/Vendor List/Zetex/bby40.lib

* ZETEX BBY40 Spice Model Last revision 18/8/92
.MODEL BBY40 D IS=7.417E-15 N=1.058 RS=.1259 XTI=3
+ EG=1.11 CJO=64.39E-12 M=1.013 VJ=2.566 FC=.5 BV=45.12
+ IBV=.1232 TT=215E-9
*
* + ISR=1.731E-12 NR=2.27 IKF 9.882 (LATER SPICE VERSIONS ONLY)

Each version of spice uses a different way to create and integrate new component models. You must become an expert in your selected version of spice. Take a look at an existing spice varicap model and work out what parameters must be changed to make your BBY40 model.

You may have to change other component values such as the LO tuning inductance and the surrounding capacitors. The original paper with the circuit includes a section on LO tuning and varicap selection, see page 5 and 6 of “Local Oscillator for FM Broadcast Band, 88-108 MHz”, from Lund University, 2012.

 

[tech99]

Sorry sir i wil like to ask the last one i think, everything was okej yesterday with sinewaveform, but today i connect the varicap and i start to get bad sinewave?
what do you think?

A varicap (or varactor) diode is swung by the RF voltage as well as the DC tuning voltage, so it creates distortion and harmonics. Varactor diodes were used as efficient harmonic generators at UHF before high power transistors became available. They were also used in parametric amplifiers, providing low noise microwave amplification.

 

[michael1978]

A varicap (or varactor) diode is swung by the RF voltage as well as the DC tuning voltage, so it creates distortion and harmonics. Varactor diodes were used as efficient harmonic generators at UHF before high power transistors became available. They were also used in parametric amplifiers, providing low noise microwave amplification.

Yes i see yesterday the same version like sir Balunce had, but maybe simulator is wrong like say Balunce

 

[michael1978]

You must use the correct spice varicap model and parameters. I do not know which spice model varicap you are using.

You know the low and high frequency ends of the FM band. The Local Oscillator frequency range needed is offset by the IF frequency. You can calculate or simulate the capacitance needed to maintain oscillation at the ends of the band. Select from manufacturers data an available real varicap that provides the required variation in capacitance. Find or make a spice model of that varicap.

The BBY40 was originally used. I google 'BBY40 spice model' and find;
http://www.gunthard-kraus.de/Spice_Model_CD/Vendor List/Zetex/bby40.lib

* ZETEX BBY40 Spice Model Last revision 18/8/92
.MODEL BBY40 D IS=7.417E-15 N=1.058 RS=.1259 XTI=3
+ EG=1.11 CJO=64.39E-12 M=1.013 VJ=2.566 FC=.5 BV=45.12
+ IBV=.1232 TT=215E-9
*
* + ISR=1.731E-12 NR=2.27 IKF 9.882 (LATER SPICE VERSIONS ONLY)

Each version of spice uses a different way to create and integrate new component models. You must become an expert in your selected version of spice. Take a look at an existing spice varicap model and work out what parameters must be changed to make your BBY40 model.

You may have to change other component values such as the LO tuning inductance and the surrounding capacitors. The original paper with the circuit includes a section on LO tuning and varicap selection, see page 5 and 6 of “Local Oscillator for FM Broadcast Band, 88-108 MHz”, from Lund University, 2012.

Thank you, i have the same model, but maybe simulator don't work, because eveything is fine without varicap, when i connect varicap everything changes the harmonics, whatever i have to do one other
THANKS MAN. greetings

 

[michael1978]

You must use the correct spice varicap model and parameters. I do not know which spice model varicap you are using.

You know the low and high frequency ends of the FM band. The Local Oscillator frequency range needed is offset by the IF frequency. You can calculate or simulate the capacitance needed to maintain oscillation at the ends of the band. Select from manufacturers data an available real varicap that provides the required variation in capacitance. Find or make a spice model of that varicap.

The BBY40 was originally used. I google 'BBY40 spice model' and find;
http://www.gunthard-kraus.de/Spice_Model_CD/Vendor List/Zetex/bby40.lib

* ZETEX BBY40 Spice Model Last revision 18/8/92
.MODEL BBY40 D IS=7.417E-15 N=1.058 RS=.1259 XTI=3
+ EG=1.11 CJO=64.39E-12 M=1.013 VJ=2.566 FC=.5 BV=45.12
+ IBV=.1232 TT=215E-9
*
* + ISR=1.731E-12 NR=2.27 IKF 9.882 (LATER SPICE VERSIONS ONLY)

Each version of spice uses a different way to create and integrate new component models. You must become an expert in your selected version of spice. Take a look at an existing spice varicap model and work out what parameters must be changed to make your BBY40 model.

You may have to change other component values such as the LO tuning inductance and the surrounding capacitors. The original paper with the circuit includes a section on LO tuning and varicap selection, see page 5 and 6 of “Local Oscillator for FM Broadcast Band, 88-108 MHz”, from Lund University, 2012.

Sir you kno what i make it, i remove the filteres and they work? WITHOUT FILTER

 

[Baluncore]

Sir you kno what i make it, i remove the filteres and they work? WITHOUT FILTER

That is a very wise move.

I modeled the filters yesterday to find the low pass frequency and the design impedance of the interface. I found that they got something wrong in their design but I have not worked out what their mistake is yet. The more I look at that paper the more suspicious I am that it was a typical student exercise. Maybe they got the phase and amplitude swapped on their transfer function?

 

[Mark Harder]

I don't know enough electronics to answer this myself. But I was wondering if the set of uncoupling caps on the 12V supply is adequate to remove any couplings of oscillations between the transistor collectors. Are these arbitrary? Or do their values and placement affect performance significantly?

 

[michael1978]

That is a very wise move.

I modeled the filters yesterday to find the low pass frequency and the design impedance of the interface. I found that they got something wrong in their design but I have not worked out what their mistake is yet. The more I look at that paper the more suspicious I am that it was a typical student exercise. Maybe they got the phase and amplitude swapped on their transfer function?

GOODMORNING;They make mistake, i don't know i am not a specialist, but when i remove all lpf, is working but frequency i think is 150mhz, but leave forgetit i make you tired, i going to do it one man he show me how to do it, i feel bad because, i make to much bussi with this oscillator leav it, i make one, which one man he told me. Ok Thank a lotsssssss Have a nice wekend.

 

[michael1978]

I don't know enough electronics to answer this myself. But I was wondering if the set of uncoupling caps on the 12V supply is adequate to remove any couplings of oscillations between the transistor collectors. Are these arbitrary? Or do their values and placement affect performance significantly?

i am either not specialist

 

[Baluncore]

Are these arbitrary? Or do their values and placement affect performance significantly?

They are critical. Those capacitors are not important to simulation but they are shown so they will not be forgotten when a real circuit is built.

One big problem with amplifiers, especially RF circuits, is when the output currents get back to the input stage which can then cause oscillation. So the design of the power supply as a low pass filter is as important as the design of the signal path.

It is important that multiple capacitors of different construction are used to bypass the supply. Electrolytics are slow and have high inductance so will need a faster capacitor closer to the circuit. Inside the circuit where active components connect to the power supply there will need to be fast ceramic capacitors, say 1nF.

 

[michael1978]

They are critical. Those capacitors are not important to simulation but they are shown so they will not be forgotten when a real circuit is built.

One big problem with amplifiers, especially RF circuits, is when the output currents get back to the input stage which can then cause oscillation. So the design of the power supply as a low pass filter is as important as the design of the signal path.

It is important that multiple capacitors of different construction are used to bypass the supply. Electrolytics are slow and have high inductance so will need a faster capacitor closer to the circuit. Inside the circuit where active components connect to the power supply there will need to be fast ceramic capacitors, say 1nF.

Thank Your Sir

 

[michael1978]

They are critical. Those capacitors are not important to simulation but they are shown so they will not be forgotten when a real circuit is built.

One big problem with amplifiers, especially RF circuits, is when the output currents get back to the input stage which can then cause oscillation. So the design of the power supply as a low pass filter is as important as the design of the signal path.

It is important that multiple capacitors of different construction are used to bypass the supply. Electrolytics are slow and have high inductance so will need a faster capacitor closer to the circuit. Inside the circuit where active components connect to the power supply there will need to be fast ceramic capacitors, say 1nF.

sorry i come back one more time to you, now is working like your, because i was making exmperiments and i did, just the frequence i don't know they change from 90MHZ to 95MHZ, i don't know how to repair this one

 

[Baluncore]

1. I have no idea what you are wanting. What is broken? When did it last work OK? Are you considering an Ltspice or a SIMetrix simulation? Please give a link to the relevant circuit.

2. You do not have to quote a complete post to reply. Select the relevant part of the post, then right click to quote that small part only.

 

[michael1978]

1. I have no idea what you are wanting. What is broken? When did it last work OK? Are you considering an Ltspice or a SIMetrix simulation? Please give a link to the relevant circuit.

2. You do not have to quote a complete post to reply. Select the relevant part of the post, then right click to quote that small part only.

No my question, was the circuit you make it in LTSPICE, i make yesterday the same in SIMETRIX, i study your circuit in LTSPCIE,, after my circuits from yesterday is working perfect, Only the tuning is not working when i put probe to the cathode it changes the frequence from 90 to 100Mhz, i mean when i change the voltage at for .8V to 6.5V (is that normal working)?
here the circutis

 

[Baluncore]

You have tangled the varicap circuit.
I believe that your C4=42pF cap was used to represent the varicap circuit.
Remove C4=42pF.
Remove C10=100pF.
Connect varicap D1 cathode, to the open bottom node of L1.

Don't forget to remove the LPF.

 

[michael1978]

You have tangled the varicap circuit.
I believe that your C4=42pF cap was used to represent the varicap circuit.
Remove C4=42pF.
Remove C10=100pF.
Connect varicap D1 cathode, to the open bottom node of L1.

Don't forget to remove the LPF.

Goodmorning sir, i did not remove the c10(47p), because is not working, C4 i and lpf i remove, now with 2V is output 88MHZ AND 6.5V is 108Mhz, output to emitter of q2, thnx man