Classic Circuits You Should Know: OpAmp Timer
ฝัง
- เผยแพร่เมื่อ 3 ก.พ. 2021
- Classic Circuits You Should Know: OpAmp Timer
6aGet 5 PCB's for $5 (plus shipping) - www.pcbway.com/
In this video we set up an LM741 OpAmp as a comparator. Then we feed the inverting input the output from an RC circuit. When the inverting input crosses the threshhold set by the non inverting input the OpAmp switches outputs.
All of my PCB designs are available from PCBWAY: www.pcbway.com/project/member...
My Amazon link: Anything you buy through this link helps support the channel, it doesn't cost you extra, and I make a few%. amzn.to/3706t6c
Yes!! I now have merch: teespring.com/stores/learnele... Electronics themed T-ShirtsIf you are shopping for electronic components, test gear or consumables please consider visiting my Amazon shop @ www.amazon.com/shop/learnelec...
Please check out / learnelectronics and pledge a dollar if you can. It will go a long way to keeping the channel alive. It costs a bit of money to buy all the items and produce these videos. You help is appreciated.
---------------------------------------------------------------------------------------------------------------------
Or....if you'd like to send a one-time donation you can use this link: paypal.me/learnelectronics
----------------------------------------------------------------------------------------------------------------------
Here is all the gear I currently use:
Oscilloscope 1: Rigol 1054Z amzn.to/2PRybtN
Oscilloscope 2: Siglent SDS1202X-E amzn.to/31Kk1yH
Power Supply 1: TekPower TP3005N amzn.to/2TeQnxI
Power Supply 2: RUIDENG DP50V5A amzn.to/2sNicSe
Signal Generator: JS2800 ban.ggood.vip/d9vk
DMM1: Owon18B amzn.to/2SbIGLs
DMM2: Aneng 8008 amzn.to/2sNQncI
DMM3: Aneng 8009 amzn.to/2S5qeEp
DMM4: Uni-T UT801 amzn.to/2S89SuL
Soldering Station1: Zeny (Yihua)862D+ amzn.to/2S49z4e
Soldering Station2: KSGR T12 amzn.to/2Wk7Dn9
Light Meter Smart Sensor AS803 amzn.to/2B2gyRg - วิทยาศาสตร์และเทคโนโลยี
Great video! I love that you didn’t have 4 way intersections in your schematic;)
I try and keep everything in simple straight lines. Cant always do that, but I try.
Important circuit. Clear, concise demonstration with all the right info.
Again. Bravo Sir!
Cool ;)
Can you create a playlist with all the series "Classic Circuits You Should Know:"?, please
Anyways, good video!
I did, months ago
Yes, that would be great!
Appreciate the addition of the white board
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
I have been watching your videos for years, i want to learn how to design electronic circuits from scratch
Yes
Behzad Razavi has the best books out there. I recommend Fundamentals of Microelectronics.
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.. : )
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.
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
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 .....
Great review of a fundamental building block in electronics. The 741 and 555 are corner stones. Very nicely done.
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 tutorial,
Many thanks
Wow! it's like you know what I'm looking for!
That was great I'm wanting to learn about opamps this video is a good start more please thanks
Great video....thanks Paul!
This is a well done video, thank you.
Lovin your classics Paul 👌
Great video!
Good job Paul.
Grat circuit, simple and brilliant way to use an OP Amp. Stay Safe
Subscribed. Excellent video.
Helpful video 👍
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
Thanks for sharing!
Great video! I'm still trying to get the hang of OpAmps.
Me too. Although I understood because Paul is great, never managed to get anything out my little op amp drawer. Not even the amusing breadboard stain suggesting previous magic smoke!
IC Timer Cookbook p 71ff. BTW...I stumbled across a PDF of that classic book in the inter tubes.
Good one! More like it please.
OHH EXCELENTE MI FRIEND THANKS YOU GOOD LUCK!!!
thank you for these elementary experiments very useful to begin in electronics. following assembly: oscillator with op amp?
Awesome!😁👍
Cool example. Looks like that breadboard has seen some heat in the past. Thank you.
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.
This is terrific, thank you so much. I thought that meant something completely different. This proof is correct, I was waaaaaaaay off.
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?
What do you think about adding a large value bleeder resistor across the capacitor so that it discharges quicker after power is removed?
you the best bro )
Would it be more applicable to use a comparator for this use case instead of an op amp?
Can you make it blinking with putting a transistor between capacitor and ground, with the base of the transistor connected to the LED?
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.
Those TL series are great opamps, you can use them
Thanks..
NICE : )
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.
cool
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!
Maybe a 555-timer in monostable mode would be as good?
@@takix2007 probably. But I have like 40 op amps and only 6 or 8 555timers. Just a different way to get the same result.
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?
Bien 👍✌️🇫🇷
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
Nice video, thank you. But pls write the symbols bigger.
c'est bon. mais comment agir sur le temps haut et le temps bas?
Yes wevwant from scratch ...
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!
👍❤️
Higher ohm pot only wastes less power. Degrees of rotation dictates granularity of control.
Hey how's it going
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?
Ocampo have about 1.5-2V of overhead at both the top and bottom. So even if the pot it 0-9 the Obama won't recognize outside of its range
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.