Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
I've designed this circuit myself aiming to generate a sine wave at the collector of the transistor, but it doesn't work. The current at the collector is DC.
I know that there are many oscillator circuits on the internet but I would like to know what the error in this circuit is.
The basic problem is that there is no feedback thru the resonating components. Note that they are tied to the base directly from the power supply. There is nothing that will make them oscillate.
There are many L-C oscillator circuits out there. No matter what topology you use, the frequency-setting components either need to be in the feedback path, or somehow arranged to kill the gain at all but the selected frequency.
There is no reason for the transistor to change its operatin point in steady state conditions (after the input transient).
An oscillator needs its perturbation at its output to feed into its input. This is not happening here.
Even if you tied the tuned circuit to the collector (as Olin pointed out) it is a parallel tuned circuit and will block feedback at the resonant frequency i.e. it won't oscillate - try using a series inductor and capacitor. Then, feed that to the emitter rather than the base. Then it is positive feedback.
