[sdiy] Greetings and Oscillations

[TheeStateMachine at aol.com]

Greetings: hello all.  just subscribed to this list after a long absence.  
seven years ago, i was on for a month or two... and was thrilled with some of 
the discussions... though i had no idea what a base current was.  but, let's 
avoid the long, introspective biography, and move on to a question.  (hopefully, 
that's not too rude!)

Oscillations: as simple as the circuit is,  i am embarrassed to say that i 
cannot get the "classic" two-opamp oscillator to work.  the integrator -> 
comparator two-opamp design should be as simple as can be... on one occassion, i 
made one that worked quite well.  so i started adding voltage control... didn't 
work.  ok.  removed that stuff, set it to it's original configuration.  
nothing.  replaced the opamp.  nothing.  made the circuit again.  nothing.  tried 
dif't opamps: TLO72, 82... 4558... nothing.

i could watch on a scope when i used a signifigantly long wavelength, and the 
integrator just rose or dropped to one rail or the other, and latched there.

so i guess the question is this:  which opamps will work for both the 
integrator and comparator sides without latching?  must i use a real comp ic?

thanks for any and all help,

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