Op Amp Comparator Circuits

A comparator chip has two voltage inputs, and outputs a voltage based on which of the two inputs is higher. There are many ways to configure these kinds of circuits and there are many uses for a comparator as I'm sure you can imagine.
This video goes through the main configurations for comparator circuits and discusses some of the different ways that you can set a reference voltage for the comparator.

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[joeh]

Excellent. Stepping through the graphs of inputs and outputs over time was very helpful. Thank you.

[AugustineAriola]

I have learnt some thing great from your video

[schitlipz]

As a Canuck too, I though we may have gone to the same campus, but your approach and some symbols are just a little different. Different enough to know we had different profs.

I guess I'm commenting on both videos here.

A very nice introduction with the history (previous vid). I liked that. Ancient circuits are neat.

General BiFET opamps make for perfectly good comparators for any hobbyist or, for professional use too. Op-Amps designed specific for comparator use are great and you can select the perfect one for your application. But general purpose BiFETs may meet your requirements.

I have read some video comments online insisting to never use regular op-amps as comparators, esp. to drive it to the rails. However, I always use BiFETs for comparing, and never had problems except for specific applications (speed). In fact, I use BiFETs for _most_ of my circuits. I so much love opamps! Compare 741s 1V/us slew rate to 081s 13V/us.

The 741 bipolar, although a classic and still used, always bothered me with that tiny little Darlington bias current. It just makes for an extra step in calculations for the biasing resistor and finding the standard values, yada yada. Whereas the TL081 or TL084 BiFETs, or similar, have given me nothing but joy! Better performance all around: Frequency response, gain, slew rate, impedances... And so simple.

I have tried to encourage other opamp video makers to distinguish between bipolar and BiFETs. I don't know why it's not emphasized more often. Seems like a very important detail.

Looking forward to the next one. [Ahhh! You just did. Slow it down there, Speedy. ]

[soufbel]

🌟 I have a problem with the comparator, My V- is 7.85V from a devider, the V+ is 50mV up or 50mV down, in both cases the results was +6.44V, I was expecting to get +6.44V end-6.44V, I chaged the IC (LM833N) but the results stay the same, (VCC is +8 end-8) may be I have to use a different IC ?! Please help

[icebluscorpion]

How about comparing the amplitude of two signals as a reference? How should I hook up the comparator then?

[elyazidbelaidi]

Error on the reference diagram by battery, do not connect it to VDD

[RixtronixLAB]

Nice information, thanks for sharing :)

[naturetoday]

3.60
3.70
3.80
3.90
3.95
Please share resister value in voltage devider

[MagivaIT]

all these explanations are the same that i find, which is great if you have a stable input voltage. what if the we're comparing the supply voltage, comparing to itself. the vdd is changing so the reference voltage is constantly changing. if ref is /2 then vdd 12v, reg is 6v, but if the vdd supply changes then the ref will change also.