strange oscillator

235

02:50:30

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i was making a general purpose comparator and it randomly started oscillating.
i don't know why, maybe it uses the feedback and the transistor power stage as delay line(?)
-nikisalli 

published 9 years ago

selman

9 years ago

I think you are correct niki, have you seen the ring oscillator in the examples tab it's an oscillator with odd number of invertors cascaded in series such that the output of the last invertor is fed back to the input of the first one to make a positive feedback loop, like that your circuit has 3 investors the comparator, CE amplifier and the power amp. The output of the power amp is feedback to the comparator input completing the loop

selman

9 years ago

Check this out. http://everycircuit.com/circuit/6350730422648832

selman

9 years ago

Meant invertors not investors ... sorry!!! Damn you auto-correct!!!

nikisalli

9 years ago

yes i was thinking that an oscillator like that would go at a frequency near the maximum frequency of the used transistors so i've never made something like that

selman

9 years ago

Yes, but since there are 3 inverters here the delay will be 3x, but I think a Hartley oscillator will show the flat-out Max frequency better.

selman

9 years ago

http://everycircuit.com/circuit/4543398378209280

GingerKing

9 years ago

Lol this looks like the exact opamp i use. I also know why it oscillates but you wont like the solution. Ill post a circuit and i promse im not copying you.

GingerKing

9 years ago

Posted it. You also have a PNP / NPN pair that is inefficient for this kind of operation just so you know

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