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An oscillator consists of an amplifier and a feedback network. Now, let us see which basic components are required to obtain oscillations.'Active device' either Transistor or Op Amp is used as an amplifier.'Feedback circuit' with passive components such as R-C or L-C combinations .To start the oscillation with the constant amplitude, positive feedback is not the only sufficient condition. Oscillator circuit must satisfy the following two conditions known as Barkhausen conditions:1. The first condition is that the magnitude of the loop gain (Aβ) must be unity. This means the product of gain of amplifier 'A' and the gain of feedback network 'β' has to be unity.2. The second condition is that the phase shift around the loop must be 360° or 0°. This means, the phase shift through the amplifier and feedback network has to be 360° or 0°.
If I wanted to have an oscillating, sinusoidal current in a DC circuit (for example a circuit with a battery, a resistance, and some other topology in series), how would I do this?
Power across the device wouldn't be too high (is there something I'm not seeing regarding the need for current/voltage values?).
I'm looking for variable frequency.
I assume that there is an implementation of an LC resonator circuit I'm not seeing? Perhaps one where the dampening effect of resistance in the circuit is offset by a logic circuit which tops up the lost power?
Would you be able to explain the factors influencing design (or point me in the direction of a source) of a DC oscillator for the various frequency ranges?Let's say I want a tunable oscillator in the low MHz range. How would you suggest I implement this?
Is a square wave or saw tooth wave acceptable in an RF transmitter circuit or does the current need to be approximately sinusoidal? I was operating under the assumption that for an RF transmitter the current needs to be appriximately sinusoidal [...]@Soeren my objective with this question is to learn about the concepts rather than produce an actual device, hence the lack of precision regarding figures.