Classic Circuits You Should Know: OpAmp Timer 

Important circuit. Clear, concise demonstration with all the right info. Again. Bravo Sir!

Appreciate the addition of the white board

Great video! I love that you didn’t have 4 way intersections in your schematic;)

Cool ;) Can you create a playlist with all the series "Classic Circuits You Should Know:"?, please Anyways, good video!

iv watch, liked, and even comment on this video already but for the life of me cant i remember watching it. took a screen shot of the schematic this time for my folder.. nice one Paul.. : )

I have been watching your videos for years, i want to learn how to design electronic circuits from scratch

Great video as usual What I like about this vid is the simplicity it's been explained, step by step and the function of each, clarifying for a beginner like me Thank you

7:43 "..we've taken something analog (this time) and we make it into something digital with the opAmp. The opAmp is either gonna be on or off, that's all is gonna be, 1 or 0". I'm learning about opAmps and I'm finding they are really nifty gadgets, you can do all kinds of stuff with them: pointing out the "analog-to-digital" thing adds a whole other perspective about them

Keep the vids coming! I love the simple but informative circuit building blocks.

I like it. Very simple. Well put. Thank you Paul. Looking forward to your next video .....

Please either make a loop over or dot at your connections. I had to go back again because you lost me. But I learned something so I'll give a thumbs up.

Simple and useful. Thanks, Paul.

You made a great point at the end of this video, well done and good circuit to know.

great simple circuit, Thank You

Great video....thanks Paul!

Great review of a fundamental building block in electronics. The 741 and 555 are corner stones. Very nicely done.

Great tutorial, Many thanks

This is a well done video, thank you.

Wow! it's like you know what I'm looking for!

This is a handy circuit if you are using an IC package with two or four op-amps in it. Some doing analogue things and some digital, for example a sine wave pip tone generator. The only problem is that some op-amps do not implement such digital circuits very well. They have limitations in the range of both outputs and inputs, exceeding these limits can result in very strange behaviour, with input signals breaking into the output of even the inverting inputs turning into non inverting. To avoid such problems, check if the op-amp input and output range includes ground, the op-amp can operate on a single rail, and maybe has inputs that can operate up to the supply rail voltage. This is a more uncommon feature. Comparators always do digital oscillators better than op-amps. I think this circuit might be improved by adding a bit of hysteresis to give it a Schmitt action. One way of doing this is to reduce the impedance of the pot and then add a resistor from the pot wiper to the non inverting input, and a second resistor from the output back to the non inverting input. Then when the output changes state, the reference point will shift slightly to re-enforce the change. The feedback resistor should be a high value, so that the shift in the reference is maybe half a volt or less. The timer accuracy is not affected, significantly affected, but the change makes the switching faster and less likely to oscillate as the capacitor voltage passes the reference, something that is likely to happen if the time constant is very large. Incidentally, it is very easy to further modify this circuit to produce an oscillator, by moving the capacitor charge resistor on to the output. The circuit input will then oscillate about the reference voltage +/- the hysteresis voltage. With the output of the op-amp switching in limit cycles across its maximum output range.

Good job Paul.

That was great I'm wanting to learn about opamps this video is a good start more please thanks

Grat circuit, simple and brilliant way to use an OP Amp. Stay Safe

Helpful video 👍

Lovin your classics Paul 👌

Subscribed. Excellent video.

Great video!

Awesome!😁👍

Thanks for sharing!

Very well explained... I almost followed along. So this could be a timmer to let you know that something else is ready or started? Nice! Thanks for the video! LLAP

Good one! More like it please.

OHH EXCELENTE MI FRIEND THANKS YOU GOOD LUCK!!!

Great video! I'm still trying to get the hang of OpAmps.

This is terrific, thank you so much. I thought that meant something completely different. This proof is correct, I was waaaaaaaay off.

Cool example. Looks like that breadboard has seen some heat in the past. Thank you.

IC Timer Cookbook p 71ff. BTW...I stumbled across a PDF of that classic book in the inter tubes.

you the best bro )

thank you for these elementary experiments very useful to begin in electronics. following assembly: oscillator with op amp?

Thanks..

What do you think about adding a large value bleeder resistor across the capacitor so that it discharges quicker after power is removed?

NICE : )

A very cool circuit. Thank you for the great explanation! The manual discharging of the capacitor makes this circuit impractical. Can you add a discharge resistor with a very high value across the capacitor to remedy this?

Thanks Paul. So, although only just woken up, could you use this,a bit upside down, as part of a circuit to limit the voltage you let a Li battery get to before charging it or similar?

Thank you sir for another great video! Since I have been following you for some time, I inadvertently notice the change of the rashes color on your arm, from red to dark brown-black, that mean deterioration of your health condition. Considering also your short breath and weak voice, I suggest you to find a Traditional Chinese Medicine licensed practitioner, they are very good to cure this kind of blood stasis heat-damp condition.

Can you make it blinking with putting a transistor between capacitor and ground, with the base of the transistor connected to the LED?

Would it be more applicable to use a comparator for this use case instead of an op amp?

cool

Great way to show how awesome op-amps are. By the way I told you a bit about the synth I’m working on and I have a question. What do you think about using old school jfet op amps like the tl072 or tl084? Or is there something newer that I should look into for buffering my outputs? Thanks for the great videos Paul, you have done more to teach me electronics than any other source and I thank you for all you do for us.

Bien 👍✌️🇫🇷

Nice video, thank you. But pls write the symbols bigger.

Yes wevwant from scratch ...

👍❤️

Hey Paul this has nothing to do with the video but how would you build a circuit where is switches a 5 volt relay with tiny amounts of current?

How can you make a circuit that will compare the temperature of germanium transistors and keeping the bias voltage for transistors Q1 and Q2 constant while the temperature changes from above 70F room temperature above to 100F and below to 50F while keeping the Bias voltages for each germanium transistor constant. What type of circuit would do this and build one in your next video lesson would be nice lesson

Could this also be a button debounce circuit too? The cap would need to be a smaller value to charge faster and use a button with resistor in series in place of the pot. Output to microcontroller or whatever it is you are controlling. Cause the output would be a clean ON or OFF without the switch noise. Awesome video!

c'est bon. mais comment agir sur le temps haut et le temps bas?

Higher ohm pot only wastes less power. Degrees of rotation dictates granularity of control.

Hey how's it going

Thank you Paul. Can you update the links in your video description, as most are leading to no were. Thanks for all the great videos!

Two things I don't understand about your potentiometer. Firstly , how does the pot value affect the degree of control? If you have 9 volts across the track, and the pot rotates 270 degrees then you have 9 / 270 volts per degree whatever the value. Secondly surely the range of reference voltage is 0 to 9, not 2 to 7?

Hi, great video as usual Mr. Paul! Now I was thinking about the 100k pot has mor resolution than, let say, the 10k pot but I couldn't agree on this! I could be wrong though but here is my logic on this issue! considering the linearity of the variable resistance there, any degree of change on the angle on either one of the pots should give the same change in voltage no matter which one are we using. Only current passing through should be less when using the one hundred kilo ohms!

Classsics...

I also anderstood that everything is better with cheese

Why didn't he respond to my comment

You lost me on the drawing as you only marked pins 7 & 4 and none of the others. Sorry to be a pain but I'm a complete beginner, learning from scratch.