[Ronja] Is an opamp oscillator reliable?

[Gyurkó Martin]

I have a working design with this type of oszillator.
But I had problems with the single ended ground. It didnt oscillate when 
i had no middle ground on a 5V system and not rail-to-rail opamps. So i 
had to generate 2.5V with some resistors an make it clean with a C and 
then it worked perfectly.


Try it!

Bye

Martin


Karel Kulhavy írta:
> I want to build an opamp multivibrator to power the onboard 48V generator. A circuit like 
> http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/square.html
> 
> However I have a feeling that the Barkhausen criterion is not met anywhere. The feedback with capacitor has to have 180 degree phase for Barkhausen to be met. This can never happen because the low pass filter has phase limiting to 0 for low frequencies and 90 for high frequencies. However intuitively I understand how it's supposed to work.
> 
> How can this circuit work then? Any idea? Is this circuitreliable at all, then?
> 
> I would like to avoid circuits which fail under certain temperature, supply voltage,
> or component tolerance for some people and work for others.
> 
> Karel
>