OP-AMP as a comparator

741 op amp comparator

I want to ask if 741 op-amp works as a comparator?! I know that it works as amplifier and for offset DC voltage...
please help!!

thanks in advance!

op-amp as a comparator

Works, don't well but works, because as comparator generally you use then in open loop or with positive feedback then the bandwidth is very small because of:

const = W*GAIN

it has others inssues too.....

Prefer use a comparator for do comparator ....

leomecma

hystresis voltage in op amp 741

Is the 741 has delay time when toggling from (+Vcc saturation) to (-Vcc saturation)...?
could you please tell me more about the characteristics of this operaitonal amplifier, if that's possible!

Thanks in advance!

Added after 55 minutes:

anyway my friends, that'sthe project which i'm working on:

**broken link removed**

I had many problems with you that's why i'm asking about 741op amp

comparator opamp

In this case 741 works because the circuit has very low frequency ... and has no acurancy measure ... in this case if comparator osc you haven't problems ...

this book has very good explanations about opamp characteristics


Here other members suggestions


leomecma

comparator op 07

741 do work as a open loop comparator but upto max a few KHz

for higher freq u may use schmitt trigger

ofcourse u wil have hysterisis problems

one added advantage will be high noise immunity

comparator

another consideration:

a opamp usually pulls the signal low or high internally. a comparator (like 311) has an open collector (and open emitter) configuration in the output stage. you can add a bjt to the opamp and build this stage externally.

op amp as an comparator

The high open loop gain of any op-amp aids in the usage of it as a comparator
we can set the Vcc supplies to the values that we want for we would be op-amp in the negative and positive saturation region but usage of rail to rail op amps would help more because of better precision of output

op amp as a comparator

any way opamp as a comparator will have output either as +Vcc or -Vcc eventhough it is having infinite gain

comparator opamp example

For Comparator, u have to use open loop configuration of 741.... It wll compare ur input with the thresold voltage that u have set already.....

ampop as comparators

yes the 741 can work as a comparator... you just have to connect one input terminal to a reference voltage.... for example if you connect the inverting input to a reference voltage, and the non-inverting terminal as your input signal. the output would be Vcc if the input is greater than the reference voltage and -Vee if the input is less than the reference voltage..

how to use an op amp comparator

Yes, but you don`t should works the 741 in this topology. If you need know more about comparator, you can read the book, Microelectronics by Rashid, or Microelectronics by Sedra.

how op amp comparator works

Usualy 741 works unstable. For example making comparator with 741 is very difficult. I use OP07 instead of 741. OP07 pin compatible with 741 and its works very good,

May be the following would be helpful...

https://www.analog.com/library/analogDialogue/archives/37-04/comparator.html

Uhm I know almost nothing of electronics so please give a simple answer. Isn't it true that an Op-amp has an anologue signal output and a comparator a digital? For example. If I would have a sensor and I would want a high signal for my Uc when the sensor output is above a certain level (around 2v) what should I use an Op-amp or a comparator?

Thanks in advance

dark_one,
The Op Amp is usually used with its output in its linear range. However, it can be used as a comparator. There are 3 considerations that may influence your decision:
. 1) Do you need fast switching of the output? If you do, you must select an OP Amp with a fast guaranteed slew rate. Gain-Bandwidth is unimportant if the slew rate is fast enough. An OP Amp will saturate its intermediate gain stages, as well as the output stage. It takes awhile for these stages to come out of saturation once the input voltage approaches the reference voltage. The time to come out of saturation is not a parameter that is usually specified for an OP Amp.
~
2) The output voltage will be approximately equal to the supply voltage. Is this acceptable? If not, most comparators have an open collector (or open drain) output. This allows you to connect a pullup resistor to any voltage that is within the maximum voltage rating of the output stage. The max rating of the output stage often is higher than the max supply voltage rating of the rest of the comparator.
~
3) If you have an unused section of a multi-OP Amp part, you may want to use it simply because it's available.
~
Whether you use an OP Amp or a comparator, it's a good idea to provide some hysteresis (positive feedback) to prevent the the output from staying in its linear range. In fact, many camparators are upen-loop unstable, so it's essential to keep them out of their linear region to avoid oscillation for the condition when the input is very close to the reference.
~
Regards,
Kral

Dear friend
from my practical experiance in building electronic ccts i donot use the 741 IC in practical comparators that i built ( althougt it could work good as comparator ) Because
1. It is not stable in working without adding more component for offset
2. It works well For +,- Vcc ( ie. +-15 volt supply )
practicaly you may have single supply voltage so you will face problem
3. the op amps of higher input impedance exist so ther are more reliable
4. comparators with higher gain exist and they are more effective
5. you will see practically there were several dedicated Op Amp for comparison and they are newer in design , less price and beteer in specification of slew rate needed for comparators