555 Timer in Monostable Mode
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- เผยแพร่เมื่อ 13 มิ.ย. 2017
- DIY Push-button Timer
In this video we set up a 555 timer IC to operate in monostable mode. What this means is that the 555 will stay in the logic-low output state until the trigger is pulled to ground. When this event happens the 555 output will go logic-high for a length of time determined by an RC network on pins 6-7-8. it can be set to stay "on" for microseconds to days depending the value of the resustor and capacitor used.
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Please watch: "Diodes: The basic building block of all digital circuits"
• Diodes: The basic buil...
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Works great thanks for sharing Artie
Thanks for making this neat turorial. An ideal learning project for a rainy sunday afternoon in quarantaine :) 555 is so freakin cool!
I know it's quite randomly asking but does anyone know of a good website to watch new series online ?
@Matias Edward Flixportal
@Jorge Lionel Thank you, signed up and it seems to work =) I appreciate it!
@Matias Edward Glad I could help xD
Haha, just found what I was looking for. Thanks, subcribed. Great videos. Love it. :)
+c0r0y Thank you, new videos every day.
Very important information.
well, it helped me a lot
The RC time constant is pretty reliable dependent on temperature.
Hi loving your channel, can u help I am trying to control a motor via a relay . I have built 2 of these circuits using a 47k and a 100 micro cap to give a approximate 6 seconds. 2 circuits so can change direction of motor. The problem I am having is they keep triggering each other . So when I trigger 1 way when that stops the other triggers sometimes it keeps on re triggering. I use separate power for motor not the circuit power. I'm really stumped with it. Hope u can shed some light pleasssseeee many thanks keep up your good work and stay safe , many thanks.
very good sir,
🙂
thanks sir its also called time delay circuit.
Thanks man.
I want to turn a relay on for 20 mins and another for 30 mins. What to do or how should I calculate/select the capacitor & register?
I want to thank you for all of these videos. Could this be used for a counter trigger with a 4026 or two if the pulse were very short? I've been studying building one and this seems to be a similar circuit to some of what I see. One question I have is I see counters built using a 555 and some built with just a switch (debounced) straight from Vcc to the trigger pin. Will either work and what would be the advantage to one over the other?? More stable pulse/counting?? I'll guess I'll build and test them - that's the fun of electronics anyway.. Thanks again - Jay.
Thums up 👍
Great video! I have a question, I want to use it to activate it on a square wave signal of 1000Hz, and I set the timing to be a bit longer then one one full wave. That works, but I want the output to remain high as long as the square wave signal is active (so the 555 needs to retrigger when it is in the on state). Now the output goes low for a short moment, and then is retriggered again... Hope you can give some advice!
Thanks bud. Just what I was looking for..trying to find a timer circuit to turn on a fan for my power supply when the temp hits a certain temp...Problem is the fan will only turn on for a second before the temp is brought down a degree..Then it repeats. Now I can just have it run for a certain amount of time
You need hysteresis. Allow a dead zone of about 1 degree on either side.
Great video! Im looking to play around with this type of circuit so this helped alot. Im just wondering what ohm resistor you used to go from pin 2 to Vcc
I looked at a similar project to this one, and it uses a 10KΩ resistor.
You make great tutorials! I like how you draw the schematic to show how it all works.
I am trying to figure out the function of each pin on the 555, and the only one that confuses me is pin 7. It’s called the “discharge” pin (for a capacitor), but I don’t know if the current is flowing TO or FROM the capacitor and the 555. If anyone knows, please let me know. Thanks!
When output is high, pin 7 is low and capacitor is discharged. Charge flows from capacitor to pin 7.
Amazingly useful video, as always! 👍 Can you please explain what is the value of the resistor on Pin2 and why it is needed? Why not just a switch? Thanks Mate!
Answer?
Hello. I hope you are still up to reply on questions.
I am curious what will happen if you press the button every 3 seconds? keeping in mind the the timing off is 10 seconds.
Is repeatedly pressing the button every 3 seconds will make the LED bulb lit? then what will happen if I stopped pressing.
Thank you!
2:41 No sorry, could you also explain how the current flows, how much current and why it flows like that. If I understand it correct, and Im green in this, and am expecting to be for a long time, the current flows constantly to trigger until the switch redirects most of the current to ground. Is that correct? if so, why does some of the current not continue to flow to trigger?
Awesome video! Just had a few questions though. What is the purpose of having a resistor connected to your button? Also, how do you determine what size of resistor to use there?
Did you find the answer of the resistor?
Just received my delivery of 555s, so will be playing around following your related videos, thank you! I assume you could use a pot to vary the time on/off, or would it need to be a variable cap? ... 👍🏻 🐍
See part 1. The pot between pins 8,7,6 control duty cycle.
👍
Excellent video Paul ( i do have your name correct if not please let me know ) Now on to building it
Thank you great info! Any chance you could show me a variable timer, using a potentiometer?... I’d want it to run a pump for different amounts of times and if need to adjust it regularly ? Thanks!
Ill put something together.
learnelectronics thanks man subscribed, looking forward to it, instead of the Led could you show a relay switching on some higher powered device? For me it would be a water pump 😛
Thanks man really really appreciate it
I'd like to see that also, if you don't mind, as I sure it would save me tons of time trying to get all 3 sequences adjusted. My best pre build concept is for the first light to be very short but bright flash, the second one to be on for roughly 2-5 seconds, and the 3rd one maybe 5 to 10 seconds.
3:18 I am missing an explanation what the limited current does for pin 6 and 7 and how the current flows when the capacitor charges and discharges. And what the pins function does exactly when the current flows to them.
What is going to be the configuration of resistor & capacitor for micro seconds
What is your Vcc and what is the size and point of the capacitor across Vcc and ground?
Hi, what if I need to have it on for 20miliseconds, that's faster than I can press the button, it then seems to stay on for as long I pres the botton
i wonder how accurate the timing gets when you time it for days
Very poor - I have tried that. Better to use a dedicated timing chip.
I'd like make three of them, wired in sequence. When the first one turned off, it would trigger the second one, (duplicate but with different time light is on), when it turned off it then would trigger a third one with yet another time; When the third one turned off, it would trigger the first one and keep repeating until I manually turned off the power source. Any links on how to connect for this array. US electrician, but newbie to electronics. Thanks in advance. logan PS. I would then use a relay on each one to 110v AC. instead of the mini "diode"? test light, that part I've done before on an analog version, to light up some xmas tree lights.
Just connect the output of one to trigger of the next.
Thank you.
Can we use this to control servo motors?
You've convinced me! I just bought 10 555's. Can this circuit be inverted, say to turn off for a certain amount of time? Great video's, I'm still catching up though.
George Chambers yep, just use a relay
That's what I was thinking, Thanks,
So...i took the resistor off of pin 8 to 7 and it still lights up. Will it just stay on?
Trying to get my head around 555 timers for a project; is there a way to make it single use? As in, Press button once, alarm sounds for 30 seconds and then will not activate again until power was reset or via another switch? Would also like to have an LED be activated and remain on as a visual indicator that the alarm had gone off. Any help would be greatly appreciated.
Yep, that's monostable mode
@@learnelectronics great thanks. Just need to get building and experimenting then! 😁
What if the supply which i give at trigger button is positive instead of ground?
Nothing happens. Trigger must be less than 1/3 Vcc.
Can we use ne 555 as vr conditioner arduino ? Like max 9926 vr conditioner speeduino ?
Thank you
Kindly I ask you how to connect relay for such circuit best regards
Will it turn off even if you still press the button?
Hi there I would like to build a circuit timer to switch on and off a fan 30 minutos at the time,what resistance and capacitor size I should use. Many thanks for your help
6000uf 100k 300k
Many thanks for your prompt reply, I am so sorry that I forgot to include the other question, that was how to add a digital screen to the same circuit.thanks again
I would like to know what happens if you hold the button down for more than 10 seconds, i.e., the time expected to turn off.
Output will stay high.
does it stays on if I hold the button or it still turns off after x seconds?
If pin 2 is kept low, output will be high. To avoid this behavior, add a capacitor in series with the switch.
I need a 1-2 sec power only need help!
What happens if you don't tap the button long enough for the cap to discharge? There is no current limiting so it's unlikely, but if you tap the button VERY quickly, a big cap may discharge to, let's say, 70% of Vcc as soon as you let off the button, Threshold (6) is still high enough to reset, and the the cap begins charging again.
Capacitor is discharged at beginning. Will start charging when switch is pressed.
Make an automotive coil igniter. 3ms
What if push is continiously ON
Output stays high.
What would i need to run one for 4 seconds and one for 7 seconds?
Im new to electronics, and dont get how to calculate this.
i don't see the pin 5 capacitor
I often dont use it
learnelectronics I understand know,Thanks
Thanks for the video, but just showing ho things are connected doesn't mean much. Monkeys can copy but not understand. Anyone who needs to know the basics shown here wouldn't understand how they work...which is the important part to thinking/solving on your own.