Op amp as a Comparator circuit

169

04:12:10

When ever the voltages at the inputs become unequal to each other the output goes directly to the positive rail voltage during the ac signal positive cycle and goes to the rails negative voltage during the negative ac cycle , giving you a square wave in the positive and negative voltages (rail voltage here is +15v and -15v)

published 7 years ago

hurz

7 years ago

A little complicated in explanation anyway, what is this transistor part behind the comparator? http://everycircuit.com/circuit/6522645423325184

BrianTronics

7 years ago

One is a npn transistor and the other a pnp , when the square is positive the npn goes into saturation and when the square wave is negative the pnp goes into saturation causes the leds to oscillate , the oscillation can be simplified of course without the transistors

hurz

7 years ago

No, the transistor do not go into saturation, there is not even a supply for then. They are just missused as diodes. For the PNP the emitter base diode and for the NPN the base collector diode. With some luck you even destroy them. Well done.

BrianTronics

7 years ago

You got to let the smoke out every now and then

BrianTronics

7 years ago

I know what I did I just do random things some times for kicks and giggles

hurz

7 years ago

So you agree the part after OpAmp is bullshit, fine.

BrianTronics

7 years ago

Yes yes relax , I changed it just for you happy ?

hurz

7 years ago

Now think about what is saturation?

BrianTronics

7 years ago

Yes I know what it is there is a depletion area within the transistor , a small current flows through the base causing the transistor to conduct from emitter to collector like a wire , like I said some times I just make random things without thinking about it

BrianTronics

7 years ago

P type doping and n type doping and all that fun physics jargon

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