How to Generate a Clock Signal with a 555 timer - The Learning Circuit
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- เผยแพร่เมื่อ 19 พ.ค. 2020
- Karen has been digging into 555 timers for a bit now. In a previous video, she did an overview of the 3 different modes in which a 555 timer can be used. In this video, Karen goes into further detail about one of those modes: Astable. In astable mode, a 555 timer can be used as an oscillator where the output automatically switches between high and low at a consistent rate as long as the 555 timer is connected to power.This is often the most common use of a 555 timer as it can be used to create the clock signal for other ICs. Karen explains what is happening inside the 555 to make this work, as well as creating the circuit on a breadboard to show how it works in a practical example: bit.ly/2Tkag8X
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Amazing! I'm am EE who struggled so hard with circuits. I almost cried watching this because I finally feel like I understand.
Many years ago I played around with the 556, two 555 timers in a single package. I put a small speaker across the two output pins, with a small potentiometer as a volume control. I got some very interesting sounds out as I varied the frequencies of the two timers, including some notes from beat frequencies or harmonics.
Using the same circuit, I replaced the speaker with a resistor and a two terminal red-green LED (one polarity emits red, the other green). By using the reset pins on each timer I could hold them in the "off" state and the LED would be dark. With one timer left to free run, the LED would flicker red. Holding that one reset and letting the other run, the LED was green. But when I let both timers run, wow! At a faster clock speed the flicker wasn't visible and I'd see yellow! At slower speeds I'd get this wonderful changing pattern of red, green and yellow, with off time showing up more as the clock was slowed. By using the two reset pin states in a binary pattern I could select Off, Red, Green and Yellow in a single LED.
One of the best 555 operational videos.
Thanks! I try.
Lets just take a moment to thank Hans for this wonderful IC.
So awesome to see the insides of ICs we take for granted. Good stuff!
Awesome tutorial. The ubiquitous 555 has soooo many uses. I have used it to build many fun circuits over the decades.
I know this is a year old, but I would like to comment on it so others will have the advantage. Two pins are not explained in this video. Only by examining the bread board at the end do you see how they are connected, with no explanation. Pin 4 is connected to positive voltage, and pin 5 is connected to ground by a capacitor (value unknown). I would say this is a great video on the 555 Astable circuit.
Crystal clear ! Excellent presentation. Thank you !
Thank you. When my brother taught me how to use it, it was how to build a circuit around it and not the internal functions of the chip.
Made a siren outputting to a LM383T 7W audio amp when I was in middle school. The circuit was from a magazine. The good old days... =)
Chiming in a bit late here. These videos are a great help for refreshing myself on the 555 timer. Also been giving me ideas for the personal projects I'm currently working on. Thank you and looking forward to your other videos.
Karen is the real Queen of electronics... learning is a pleasure when watching her videos... and after all these years of struggling the first instructor who makes me understanding... Thanks a lot!
Thank you. The best 555 vid. Excellent teaching by the presenter.
It is the best explanation video I've found on the internet. Thank you so much!
Thanks for the simple and awesome explanation..
Thank you, Karen. With this video, I have reproduced what you have done.
Brilliant, thanks for such a clear explanation, worked for me!!
555 is my favorite. Thnx for this video.
You are the best! I feel so calm now about the lab I was going to do:)
Great presentation. Nowadays it is so easy to generate signals with the PWM features of even the most basic MCUs. However, for detecting missing pulses, it is hard to beat the simplicity and elegance of a 555.
Nice and clear explanation. Thank you for the post
Thank you for your videos, they are very instructive and I like them very much! 😊
You're just a God of teaching...!
This really helped, thank you!
U r really awesome I really got to know how the 555timer works in astable mode.....tq sm
Thanks for a good explanation...
Very helpful information.Thanks alot Madam.
great video, thank you for sharing this!!!!!! lovely 555 timer, miss.
Love the videos Karen you do a super job of explaining things! Keep up the great work!
Thanks, Karen!
impressive representation ❤
This is absolutely awesome. How would you tie input from the naval observatory atomic clock to this clock signal?
6:42 I think by "pin 6 connects to Vcc with this 1k resistor" Karen meant pin 7.
Great video! Thanks!
Thanks karen . Very helpful
Hello,
In this demonstration, how do we calculate the value of the resistor connected between the discharge pin and the VCC?
Really well explained, so that even this absolute novice could understand everything. What I need to do now is find a video that tells me how to set the output to a specific rate so that I can use it to act as the counter for a binary clock project I have in mind.
you can get the formulas from the datasheet. Just do a google search "555 datasheet"
What's the purpose of the small capacitor connected to ground and pin 4 that is not mentioned in the video? Thanks
You could use them in the railway crossing sign. You could use them to produce a 60hz square wave and feed 12v into a transformer to make a simple inverter.
Hi, I'm beginner. I'm quite confuse, (at 5:11) when Input of RESET LOW & input of SET HIGH, then the output of "NOT Q" is LOW ?
Am I wrong?. You say and I quote "pin6 connects to vcc with this 1 kohm resistor" wrong. the video clearly shows it is attached to a hole that lines up with pin 7. What do I change to make it go faster
? Is there more than one way? What's the effect of larger caps?
Great, thank you.
How to make it a constant clock, not dependent on temperature and device errors? should we use a crystal?
The 555 isn't meant to be extremely accurate. Choosing precision resistors and capacitors with good temperature ratings (accurate over a wide temperature range) helps, as well as a stable power source. Choosing specific 555 part numbers, too. Commercial, Industrial, and Military specific versions operate over their own temperature ranges.
I don't recall seeing a 555 circuit using a crystal for a time reference, but I wouldn't be surprised if someone had done that! I'm trying to think how that would even be done! Good question!
You can connect a crystal microphone to the CV pin and ground and the frequency will very according to the signal on the CV pin.
I'm thinking I could make a buzzer, but what if I wanted to change the discharge time vs the charge time?
I seems there is also a new version of this, the 666, it is an end-of-timer.
If I understand the concept of operation correctly, you could also change the frequency by using a smaller capacitor.
How is the signal quality compared to the real digital clock generator used in consumer devices?
I built "The Internet" with a 555 timer. Not the former Arpanet mind you... But a fan built copy of "The Internet" from the IT Crowd. It was a fun and simple project.
Mam, could i know how it forms clock signal as time to take charging and dicharging of the capacitor is not equal?
You taught me so much just now. Thanks! an I like your style.. I dress similarly so its cool to see someone else with stylish attire an be into robotics =]
good video
Damn. Feeling all nostalgic about skulking about in Radio Shack after school reading the Forest Mims 555 engineer's notebooks without paying for them.
Please Can you make bell door electronic multi tone with ic 555
Thanks for your.
Perfect explanation from the Electronic Engineers “Swiss-Army-Knife”. And when you show the values from the internal Resistors (5k) then you know where the name comes from 😎
Supposedly that is an urban legend and has nothing to do with the part number - just coincidence.
5:42 I'm confused by how that transistor prevents the capacitor from being connected to Vcc.
I would also think that the resistor on left would have to be >= to the one on the right for this to work, but the demo clearly shows that's no the case.
I have 2 questions (I am an IC trader) :
1. What if we vary the value of capacitor by means of a variable capacitor? Is it mandatory to use electrolytic capacitor?
2. In all inverters I open, I have never found 555 as oscillator while on oscilloscope the signal look like that of oscillators (SG3524/SG3525/CD4047/...). Why inverter manufacturers don't choose 555?
You can absolutely change the value of the capacitor rather than the resistor. Just keep following the equation for time.
As for what kind of capacitor, I used an electrolytic because all my ceramic caps were too small of a value and the blink would be so fast that it would be imperceptible. I feel like you would want to use a polarized cap, though. But that's my intuition saying that. I haven't thought deep into the science of why.
As far as why manufacturers don't use 555s as oscillators, maybe cost, scale, perhaps there are custom chips that are self-contained oscillators rather than how the 555 needs an external RC circuit? The reason may be conditional of the application.
Can this clock singnal for a 12 v realay
Nice
I want to receive signals every 1 second. what should be the value of resistance
T high= 0.695(Ra +Rb)C
T low= 0.695*Rb*C
Ra, Rb are connected between 7 and 6 where Ra is connected to Vcc.
At 6:43 you say "pin 6 connects to Vcc with this 1K ohm resistor".... should actually say pin 7.
I wonder if someone know how to implement 555 timer to build a circuit that generates short high pulse and long low, I mean something like 10 minutes delay (LOW) and 1second (HIGH) in continuous cycle.
Excellent and concise explanation. The only cons is the somewhat unpleasant vocal fry of narrator (smart masculine women sport with this one).
4:20 The drawing of that capacitor is inaccurate. It should have a polarity.
Please make a video for 6502 and 8086
MPs are a bit down the road, unfortunately.
Flowing over my head..😥😥
Hi Karen
Hi! [waves]
I want to power an 8 bit shift register and drive a 7 seg display. wish me luck
1:19 it seems nobody in this channel read these comments since they insist on keeping the same mistakes; the 555 does NOT have a Flip-Flop, it is an SR-Latch. It seems they do it on purpose just to confuse...
I agree with you but many folks call it a flip flop. One of those chicken and egg discussions like "is it a delta-sigma or a sigma-delta converter?".
An SR Latch is a type of Flip-Flop. You're claiming a square isn't a rectangle .
6:43 Should be "pin 7"
i tried this experiment , but it failed
Hey you said pin6 is connected to a 1k resistor in the first point and then you switched to say pin7 in the second place and the picture shows pin7 is connected to vcc thru a 1 k resistor so when you started saying the 1k resistor was going to pin 6 you were wrong and confused me, so get your shit right.
❤❤❤
neat
4 Da Utube algorithm!
Drawing closed by your text....could you made the professional tutorial ?
I think I've hit my limit of electrical knowledge because I understood none of that. :(
Oh no! Anything I can help with?
@@maker_karen1785 There just seems to be something about electronic logic that is counter intuitive to me. I understand, roughly what a 555 does, but HOW it does that is where I get lost.
@@maker_karen1785 Actually, a suggestion for a good circuit simulator might help. There's a lot out there and I don't know what to look for in one.
What's the purpose of the small capacitor connected to ground and pin 4 that is not mentioned in the video? Thanks