Why wont this oscillator work? (And suggestions for project)

[linkyta]

Hi all, Im suppossed to build an electromagnetic field detector, I was thinking about using a coil as a probe to detect low freq changes in magnetic and electric fields (as to detect hidden wiring for example) (its not supposed to use any special purpose IC's)

I know absolutelly nothing about osc. theory, so I got this schematic but it just wont work, could anybody help me out? Or do you have a ckt that actually works or any other suggestions? thanx a lot

 

[flatulent]

Re: Why wont this oscillator work? (And suggestions for proj

You do not have the proper feedback. You have a gain of 1 op amp circuit and put the LC between the inputs.

You would be better off doing a one transistor oscillator circuit that you can find in many books.

 

[marshel]

I think the LM324's + - node should be reverse connected.
For now condition, it is negativer feedback and wont oscillate, you shoul have a positive feedback to get a oscillation.

 

[linkyta]

Ok thanx for your help, i think i need to check that oscillatr theory

 

[marshel]

well, I am not familiar with oscillator theory.
But for a negative feedback condition, maybe the oscillation occurs only when the amp does not have enough phase margin in high freq.