The OpAmp Comparator and Voltage Divider - Electronic building blocks

The really good page to learn all about OpAmp comparators:

A good voltage divider calculator that takes three values to calculate the fourth.

In this video I go through how the OpAmp Comparator works and can be used in modular projects or any project where you need an on or off value depending on a threshold value from a voltage source.
With this knowledge I think you can all get a few ideas for some fun modules that might be fun to build?
Let me know in the comments!

[skriptico]

uh i like this. maybe is the time i finally understand oas. thanks a lot K. [edit] great lesson, i'll rewatch this with my breadboard handy. We need more building blocks like this!!!

[RoyAndrews]

Awesome video.. only a person that's been studying for a long time such as myself would actually appreciate this.. because I understand and can relate. 🙂 (+ 1).

The whole entire thing about electronics is all about variable voltages and what you do about them.. don't forget about Ohm's law and the fact that everything else is directly related and only separated by the different values.

When the current changes so does the voltage. Ohms Law.

You vary the voltage on the gate, you vary the voltage between drain and source, but at a higher voltage range.

Happy Trails. 🐒

[matrixmodulator]

Thanks for this video, very intuitive to understand the way you explain it. I don't know if you plan to but a video like this for transistors would be very nice too!

[rattusrat]

Thank you. Great explanation. Finally understod this. Will use it in my slew circuit.

[jp]

You can also flip the voltages and put ref V on non inverting input and source voltage on inverting input and it will reverse the logic of the voltage comparison. This comes into play if you want to have two comparators with a window between trigger voltages. You can also have a voltage divider ladder and make ladder of voltage comparators which is essentially what is inside the LM3915 to make a LED VU meter circuit. Very useful circuit building block circuit.

[pbartmess]

This is very interesting! Thanks for sharing the info. I can now see how useful these circuits can be.

[deankay]

Kristian, I will looking at your other videos and checking out the links you provide. I am an automotive guy, forced into retirement so building instead of buying. Question: The circuit I am trying to build is controlling a very small dc motor, built with 3 terminals for ground, CCW and CW. It is geared to a two pin pot. This describes a hot/cold actuator sold new for $10 +_. But using an Op Amp, control circuit can be 5 Vdc via regulator, but out put at 12.8-14.2 Vdc or car system voltage. A pot on the dash when turned, moved the motor CW until the internal pot creates a voltage input matching a variable input that stops motor movement. Turn the dash knob the other direction, the motor rotates opposite way. I have spent hours to figure out what seems like a simple circuit. 1 Op Amp or 2, I have three cabinets of electronic parts, bread board and Fluke 87 - V. Can you help? I just need a second vehicle that old but tough that I can drive (6'3" tall) but something my wife can used. I create a service manual for each part, system or component that even a GM dealer tech can work on. Thanks for any help or suggestions as I can't find anything close to work.
Subscribed and liked and willing to do the work. Just waiting for lumbar fusion #4 in June.

[AkhtarDanish]

I have a question about Arduino
How to make automatic watering system using old washing machine solenoid valve 12 volt and Arduino using soil moisture sensor so system can water the plants as needed! Please make a video on that!

[clayjeffries]

I will have to look closer... Rf / Rg =Av ? I thinink the value is the diference not a default max out of the voltages … just perplexed

[Sekhar_Home]

Why the output voltage not equal to 12 volt. Why drop of 1.2 volt..

[clayjeffries]

ahh all apologies .I see you are working with "unity gain" so your usage is sound ..again I apologize that I missed that