# Self-designed sine wave oscillator problem (frequency and waveform)

I designed a sine wave oscillator, but the frequency isn't correct and the wave shape is weird. I use 5V single supply. I create a 2V common point to be virtual ground. The opamp is acting as a non-inverting amplifier. There is a feedback diode in parallel to control the amplitude. The LC in series should act as a bandpass filter to select the frequency. What's wrong with the circuit?

I built the circuit in practice, and the result is almost the same as the simulation result.

• Does your oscillator circuit follow any known theory, or is it something of your own invention? Not that the latter is a problem. I learnt much of what I know by inventing a complicated something that didn't work, then discovering that there was a wealth of information on how other people had been solving issue for years with a simpler circuit. I'm glad simulation and practice produce the same result, it narrows down the things that need to be fixed. Commented Feb 1, 2023 at 15:25
• I designed a sine wave oscillator <-- where's the theory behind this design? What frequency did you expect it to oscillate at? Did you try using 1N4148 diodes instead of the 1N4007s Commented Feb 1, 2023 at 16:42
• I remember seeing this phase-shift oscillator answer here and it appears to conform to prediction. Commented Feb 1, 2023 at 17:16
• Regarding the theory behind this design: It is the same principle as the Wien oscillator - a passive bandpass in the pos. feedback loop and a fixed resistive negative feedback loop. For oscillation, the pos. feedback must be somewhat larger than the negative one (at w=wo).
– LvW
Commented Feb 1, 2023 at 17:23
• thank you. seems like I figure out yhe Commented Feb 7, 2023 at 21:26