Re: LC circuit

[John Popelish]

Ken wrote:
> > Here is an LC meter that uses a comparator to produce the negative
> > resistance to keep an arbitrary LC tank oscillating.
> >
> > http://my.integritynet.com.au/purdic/lc-meter-project.htm#circuit-osc
>
>
> Looks good, thanks
> here is a link with my circuit so far and my problem:
> http://www3.sympatico.ca/lerameur/ 

As I understand your problem (correct my errors) you want to cause an 
LC tank to oscillate.  But you don't want it to be driven into 
oscillation, continuously, but given a blast of energy only when the 
oscillation has damped down to some minimum amplitude.  I don't 
understand if the blast is to be a single pulse, of a negative 
resistance that feeds energy in, slowly, till the amplitude gets to a 
second, larger amplitude.  Then there is some other feature about 
operating only when the supply voltage is larger than some value.