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Q&A Results of analysis of Hartley oscillator dont make sense

This LC circuit depends on several criteria for stable linear oscillation; 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or ...

posted 2y ago by TonyStewart‭  ·  edited 2y ago by TonyStewart‭

Answer
#9: Post edited by user avatar TonyStewart‭ · 2022-08-13T15:44:26Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs that have much higher Q for square wave clocks or nonlinear feedback for sine amplitude unity-gain AGC-like control.
  • https://tinyurl.com/2nu4eyrb
  • ![bode](https://electrical.codidact.com/uploads/9X8nW1A1XKoLBFFSGZRAKUjA)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs that have much higher Q for square wave clocks or nonlinear feedback for sine amplitude unity-gain AGC-like control.
  • https://tinyurl.com/2nu4eyrb
  • ![bode](https://electrical.codidact.com/uploads/hnbeCU1otSXh4fvV83q93KwK)
#8: Post edited by user avatar TonyStewart‭ · 2022-08-13T15:42:16Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs that have much higher Q for square wave clocks or nonlinear feedback for sine amplitude unity-gain AGC-like control.
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs that have much higher Q for square wave clocks or nonlinear feedback for sine amplitude unity-gain AGC-like control.
  • https://tinyurl.com/2nu4eyrb
  • ![bode](https://electrical.codidact.com/uploads/9X8nW1A1XKoLBFFSGZRAKUjA)
#7: Post edited by user avatar TonyStewart‭ · 2022-08-13T15:40:10Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs.
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs that have much higher Q for square wave clocks or nonlinear feedback for sine amplitude unity-gain AGC-like control.
  • https://tinyurl.com/2nu4eyrb
#6: Post edited by user avatar TonyStewart‭ · 2022-08-13T15:38:30Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • This design is not intended to be ideal, and there are better designs.
  • https://tinyurl.com/2nu4eyrb
#5: Post edited by user avatar TonyStewart‭ · 2022-08-13T15:21:00Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift ( with 3rd order LC network) plus 180 degree inversion to achieve the oscillation criteria of 0 or 360 deg at gain >=1 Thus each reactance affects fo.
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
#4: Post edited by user avatar TonyStewart‭ · 2022-08-13T07:38:56Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • A variation was made by adding the L1,L2 ground resistance for a notch filter effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • The highlight of this answer is to show the results of resistance ratios and hFE can be significant.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
#3: Post edited by user avatar TonyStewart‭ · 2022-08-13T07:24:03Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE = 10 to 50.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
#2: Post edited by user avatar TonyStewart‭ · 2022-08-13T07:23:25Z (about 2 years ago)
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE.
  • ![sim](https://electrical.codidact.com/uploads/QKdrsPRNqGW8D7hRPaE6MJ8e)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
  • This LC circuit depends on several criteria for stable linear oscillation;
  • - 180 deg phase shift plus 180 degree inversion
  • - adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
  • - Only 1 capacitor is necessary
  • An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
  • - keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements.
  • - The feedback cap. and H bias were also replaced with one feedback resistor, R2
  • - By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave.
  • - Excess gain will clip the sine wave.
  • The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE.
  • ![sim](https://electrical.codidact.com/uploads/V2v4Y2nCdGzEXEvjjB1tHaR3)
  • [Falstad Simulation]
  • https://tinyurl.com/2nu4eyrb
#1: Initial revision by user avatar TonyStewart‭ · 2022-08-13T07:22:38Z (about 2 years ago) 
This LC circuit depends on several criteria for stable linear oscillation;

- 180 deg phase shift plus 180 degree inversion
- adequate bias current and impedance ratios with negative feedback ratios at DC and at fo.
- Only 1 capacitor is necessary

An improvement was made adding the L1,L2 ground resistance for a deeper notch effect.
- keeping the resistance ratios of R2/R3=1.5 to 3 range that affects feedback attenuation and impedance range used to satisfy requirements. 
- The feedback cap. and H bias were also replaced with one feedback resistor, R2
- By tuning hFE to lower values, one can improve R ratios for sufficient gain to oscillate with pull up/down for a symmetrical sine wave. 
- Excess gain will clip the sine wave.

The sensitivity to each resistance part value in the simulation gives more insight than the math and leads to a stable result. In reality, hFE is nonlinear with current, but I did add a slider for constant hFE.





![sim](https://electrical.codidact.com/uploads/QKdrsPRNqGW8D7hRPaE6MJ8e)

[Falstad Simulation]

https://tinyurl.com/2nu4eyrb