These videos are absolutely invaluable. This one in particular was fantastic. When you showed the circuit, I thought, "But what's inside the 555?" and you explained it just then. Same with the 1.1 factor, I thought, "Why is tha... oh he's going to explain it." Awesome.
+Christopher Poplawski Here's a cool little kit you might be interested in. You can build it and see what is inside the Trip5 IC. www.makershed.com/products/the-three-fives-kit-a-discrete-555-timer
+Robert Calk Jr. Oh, that's just awesome. I love that the PCB is made to look like an oversized 8-pin DIP... It's not exactly practical, but it would make a good teaching tool or gift.
Yet another superb video. Everything is nicely explained and nothing left to chance. 20 years ago I built a similar circuit to add an intermittent function to the windshield wipers of a 1987 Chevette I owned. I connected it in series with one of the motor terminals. Conveniently, interrupting power to this terminal caused the wipers to stop after reaching the "down" position. I put a switch on the 555 Reset input to hold the relay closed for normal wiper operation, and a 10K pot was used to vary the interval. At the time this was one of my greatest achievements, and remains so. Oh...oops
Thank you again for another great video. The combination of a real world application, demonstrating the built up circuit and the underlying theory with a little bit of maths was just about perfect.
I love this tutorial, particularly the schematics at the beginning! Every time I want to use a 555 chip, I always have to spend 30 minutes on the datasheet in order to understand the internal circuit. But this time, when I looked at your schematics, I understood how the internal circuit works in less than a couple minutes!
Great timing. I was looking through the TTL cookbook yesterday and I saw a monostable multivibrator and wondered what it was. I planned to do a search and got distracted. This is even better than a Google search result. I program PLC's for a living so when I heard the term one shot I knew what it did. Thanks for the video explanation! It was outstanding as always.
Another GREAT electronics tutorial. Back to Basics is a nice way to learn -- or re-learn, some fundamental concepts like the 555. Thanks again for all the wonderful videos.
Great video as always. It's great to see such clear explanations starting from the high-level idea and working down into the math. When I first learned about this device as a student, I could not find such a great explanation. Instead, most examples would focus entirely on the schematic and using the already-simplified formula to pick component values. It's explanations like yours that help us to understand how and why things work so that we can learn to design our own things rather than just copying what others have already done. Thank you and keep up the wonderful videos.
Thanks again Alan for yet another exceptional video. Your content selection, your way to precisely explain and entertain, the pace of your speech and your professionalism are simply the best combination for learners like me, you're a terrific teacher!
Let me just say that anybody who would thumbs down one of your videos is an asshole. You’re channel is absolutely invaluable for electronics students and should be required watching for college students!
+w2aew Great! No amount of theory can make your video less valuable: the expert point of view is something that always boosts the learning experience, and even more so if it's expressed by someone that is capable of explaining everything as good as you can. I can't wait to review all of your back to the basics; but may I suggest you review your playlists on your channel? I think that it can add some value to include a playlist for the basics videos
Thanks Alan. I have a 555 night-light with 7 LED's on a breadboard. I control the 555 with a CdS Photocell through the reset pin and ground. It's been running every night for 2 1/2 years with no problems.
+Robert Calk Jr. What light was it sensing? Outside? Or other lights in the room? I used a 555 for several years to switch on 20m or so of LED-strips (selfbuilt from 5mm LEDs as the premade strips weren't really available then; they would have been way to bright anyway) in the hallway as soon as it got dark outside. In a setting like that using the reset pin wouldn't work because you need a considerable amount of hysteresis to not have flicker. In both our cases the 555 is already "overkill", I didn't use any timing function and in your case you don't even use the comparators if you just toggle the reset pin ;)
+superdau It's inside in my workroom. It will flicker some if the light is kind of low, but most of the time the lights are either off or on. I stumbled on it accidently while playing with the IC when I first started learning electronics. It rarely flickers, but in low light the LED's receive less current so they are not as bright. It doesn't take much sunlight coming through the curtains to turn it off. The 555 is a pretty handy IC.
+superdau I kind of disagree with the "overkill" part. On another breadboard I have an analog "night-rider" circuit built with 6 LED's powered through a Trip5. I have another "night-rider" circuit on an Arduino with 6 LED's also. I must admit that I prefer the analog, even though it requires more components and some nifty placement of all the diodes. But the analog circuit just seems to be warmer, and more fluid.
Thanks for the video! When I had first started learning electronics, I messed around with 555s, but I never really understood how they worked at all (op amps were still a mystery to me). Now that I've been learning for a while, it was nice to go back and finally see how they (555s) worked and actually understand it.
Ah, my old teenage favorite IC. You can do anything with the 555. Ive even heard that some fairies can create an audiophile class A amplifier with them however, it's just rumor though. Great as always Alan. Oh, I keep hoping that I will find one of those MDO scopes laying in the street, after falling off the Tek truck. LOL Yes, I would be so glad to own one even with dents and scratches. They are some kind of scope. I'm saving my pennies.
10:15 "We know we're going to be charging up to two-thirds of Vcc". That's because of the three 5K resistors inside the 555 between the comparators that divide Vcc in threes, right?
+Jac Goudsmit Yup. The voltage cannot charge higher than 2/3rds at that point in the circuit, so as far as the calculations are concerned, that's out "max charge".
I swear you must be related to Forest Mims, though I have learned more from you, and you are a real scientist. Thanks again. Beat EE channel on the web.
+PelDaddy No he meant Beet EE channel on the web. If you haven't watched these videos while eating a bowl of borscht, you don't know what you're missing! P.S. Don't get any borscht on the scope or might have a red trace for one of the scope inputs...
Love your "Basics" videos! Two Questions: 1) What's the best way to connect two 555s for a "modulated carrier"? I'm never sure if I'm doing it the right way... and 2) What's the Control pin for? Any examples would be a great help.
I've only recently seen your ch. & subscribed.... your presentations are extremely fluent & precise... I really like them.....In this one , the case of the I/p being held low / stuck low , beyond o/p p.w. ( elapsed time )was not covered.... maybe you cover it in another presentation...
Another excellent video. Thank you. General newbie question though. Could you drive the relay directly from pin 3 (out) of the 555 instead of using the intermediate transistor?
+Bobo Johnson It depends on the relay and the drive capability of the 555. Note that it cannot swing to VCC, so this may limit the ability to properly drive a relay.
+DoItYourselfMusician If I tied it directly, I wouldn't have been able to momentarily lower the voltage with a simple normally-open switch like I did (that would've shorted the supply to ground.)
did i say anything about free energy. you pay for what you get, from what energy it creates. and it takes energy to create what it makes... so that blows your "dumb ass" statement out of the water. till you test the theory of it's principles and prove it wrong. and you can't. because someone has beat you to it and proved it's principles and usage. just keep you food trap shut and lies wont spew freely.
I've been trying to get this circuit to work but when I ground pin 2 the load energizes and then just stays on. I'm getting rather determined in figuring out what I've been doing wrong. (I think I need Pre-beginner level)
Ah hah! If you hold the Trigger input low, the output will stay on. If you want the output to give the 1second pulse even if the +5v signal stays low, then you'll need to AC couple the +5v signal to the Trigger input. Keep the pull-up resistor on the Trigger input.
@@w2aew That's fantastic, Alan. Really great channel, awesome tutorials. They are concise but complete, they unite theory with lab practice. Thanks a lot. Cheers Mark
It all depends on how much money you want to spend. There are premium brands like Tektronix, and lots of less expensive value-based brands, plus a lot available on the used market.
It seems you have changed something with the video quality or frame rate? It's not as smooth as your previous videos. You may have resolved this in later videos, i am slowly catching up 😊
It was TH-cam. They changed the frame rate on any videos that I uploaded in .MTS format. My originals are 30fps, but they drop it to 15fps on this format. Once I noticed that this was the reason, I changed the format to .MP4. But, there are many videos that got caught up in this change before I noticed it.
w2aew ok, I thought it might be something like that, i am now at video 244 and yes you fixed it pretty quickly. How can contact you and ask you some questions about topics for videos? I have linkedin connection requested you and tried fb messenger but to no avail 😊 I feel like i am stalking you now lol
I hope you can help me with this. I'm building an external flash for a digital camera. here is a link on how a flash circuit works if you don't already know: www.diyphotography.net/how-to-build-a-flash-with-an-optical-slave/ as the article said, a typical flash circuit dumps all the capacitor's energy as soon as the xenon is ionized. what I want to do is add a monostable multivibrator to pulse the energy coming from the cap so it uses less than the full charge so I can get multiple small flashes from one cap charge. I am using a 320v 220 micro farrad cap and I want it to use just 1/3rd of its full charge at a time
Hmm - I'm not sure this will work for a few reasons (but I'm not an expert on flash tubes..). The firing of the tube uses a triac (thyristor or SCR), which once triggered, continues to conduct until the current goes away. You can't turn it off once it's been triggered unless you do so with another switch type device in series with it. The other problem is that if you discharge the main cap to 2/3rd or 1/3 of it's full charge state, the voltage at the caps terminals will only be 2/3 or 1/3 of the normal flash voltage - which might not be enough to ionize the Xenon tube.
I know that it works because a lot of flashes today have red eye reduction function but still only use 1 capacitor so it has to be being pulsed. also the xenon is ionized from the trigger transformer
Ok, good to know. It's clear that I don't know that much about the drive requirements of the xenon flash tube. I can imagine maybe they replace the SCR with something else, maybe a mosfet driven by a pulsed source, which could be 555 based. Or maybe use two (or a 556) to create some gated pulses.
w2aew that's the part that I'm trying to understand. how would what you just described work? modern flashes DO use an IGBT and have components that have MOSFET.
You're basically replacing the SCR with another device (like the IGBT or MOSFET) to drive the trigger coil. Unlike the SCR with stays on once triggered, the Gate of the IGBT or MOSFET can be driven from a monostable pulse to control the amount of time that the device is on. I don't know enough about the drive requirements of the trigger coil to know how to design the details of that.
These videos are absolutely invaluable. This one in particular was fantastic. When you showed the circuit, I thought, "But what's inside the 555?" and you explained it just then. Same with the 1.1 factor, I thought, "Why is tha... oh he's going to explain it." Awesome.
+Christopher Poplawski
Here's a cool little kit you might be interested in. You can build it and see what is inside the Trip5 IC.
www.makershed.com/products/the-three-fives-kit-a-discrete-555-timer
+Robert Calk Jr. Oh, that's just awesome. I love that the PCB is made to look like an oversized 8-pin DIP... It's not exactly practical, but it would make a good teaching tool or gift.
+pillsnotbills
Yes, it is a great teaching and learning tool.
same reaction here!
The older I get, the more I like the Back To Basics! Thanks!
That's because we've so much more in our heads to forget... At my age I must've forgotten one heck of a lot of stuff already! :-)
this is the best tutorial for 555. thankyou sir
Yet another superb video. Everything is nicely explained and nothing left to chance.
20 years ago I built a similar circuit to add an intermittent function to the windshield wipers of a 1987 Chevette I owned. I connected it in series with one of the motor terminals. Conveniently, interrupting power to this terminal caused the wipers to stop after reaching the "down" position. I put a switch on the 555 Reset input to hold the relay closed for normal wiper operation, and a 10K pot was used to vary the interval. At the time this was one of my greatest achievements, and remains so. Oh...oops
Your back to basics videos are great Alan, please keep making them. Priceless content. Thank you.
Thank you again for another great video. The combination of a real world application, demonstrating the built up circuit and the underlying theory with a little bit of maths was just about perfect.
Probably the best 555 tutorial I've seen.
It is always pleasure to watch your tutorials. Thanks!
Best explanation I have seen on how the inside of the 555 works. Thanks you.
Always good to get back to basics. Thanks Alan for a great grass roots explanation! 73 - Dino KL0S
I love this tutorial, particularly the schematics at the beginning! Every time I want to use a 555 chip, I always have to spend 30 minutes on the datasheet in order to understand the internal circuit. But this time, when I looked at your schematics, I understood how the internal circuit works in less than a couple minutes!
Great timing. I was looking through the TTL cookbook yesterday and I saw a monostable multivibrator and wondered what it was. I planned to do a search and got distracted. This is even better than a Google search result. I program PLC's for a living so when I heard the term one shot I knew what it did. Thanks for the video explanation! It was outstanding as always.
Very informative. Looking forward to your videos on other configurations of the 555.
As a new EE student, this was very informative and entertaining. Thank you sir.
Another GREAT electronics tutorial. Back to Basics is a nice way to learn -- or re-learn, some fundamental concepts like the 555. Thanks again for all the wonderful videos.
Great video as always. It's great to see such clear explanations starting from the high-level idea and working down into the math. When I first learned about this device as a student, I could not find such a great explanation. Instead, most examples would focus entirely on the schematic and using the already-simplified formula to pick component values. It's explanations like yours that help us to understand how and why things work so that we can learn to design our own things rather than just copying what others have already done. Thank you and keep up the wonderful videos.
Thanks again Alan for yet another exceptional video. Your content selection, your way to precisely explain and entertain, the pace of your speech and your professionalism are simply the best combination for learners like me, you're a terrific teacher!
This is way more worth than my engineering classes. Love it.
Let me just say that anybody who would thumbs down one of your videos is an asshole. You’re channel is absolutely invaluable for electronics students and should be required watching for college students!
Awesome video, perfect teaching as usual... Greeatings from Venezuela.
You explain things very well, as an amateur it's very helpful! Thank you!
Superb explanation of 555 functionality. Thank you!
Explanation is always very informative. Please plan a detailed series on basics to advanced level about some of the good OP Amps.
Fantastic as usual. Your "back to basics" videos are awesome. Can't wait to see more, be that more 555 videos or anything else! Keep it up man!
Thanks! The next "Circuit Fun" video I'm planning also includes a 555...
+w2aew Great! No amount of theory can make your video less valuable: the expert point of view is something that always boosts the learning experience, and even more so if it's expressed by someone that is capable of explaining everything as good as you can.
I can't wait to review all of your back to the basics; but may I suggest you review your playlists on your channel? I think that it can add some value to include a playlist for the basics videos
The pearl earring in the corner of the breadboard was a nice touch...
+Ivaylo Iliev Essential to the circuit I'm sure
+Ivaylo Iliev That's the noise stabilizer for the breadboard. It also acts to make sure that ground truly stays at ground potential.
back to basics ...is all I needed. Thank you for this great work
Thanks Alan. I have a 555 night-light with 7 LED's on a breadboard. I control the 555 with a CdS Photocell through the reset pin and ground. It's been running every night for 2 1/2 years with no problems.
+Robert Calk Jr.
What light was it sensing? Outside? Or other lights in the room? I used a 555 for several years to switch on 20m or so of LED-strips (selfbuilt from 5mm LEDs as the premade strips weren't really available then; they would have been way to bright anyway) in the hallway as soon as it got dark outside. In a setting like that using the reset pin wouldn't work because you need a considerable amount of hysteresis to not have flicker.
In both our cases the 555 is already "overkill", I didn't use any timing function and in your case you don't even use the comparators if you just toggle the reset pin ;)
+superdau
It's inside in my workroom. It will flicker some if the light is kind of low, but most of the time the lights are either off or on. I stumbled on it accidently while playing with the IC when I first started learning electronics. It rarely flickers, but in low light the LED's receive less current so they are not as bright. It doesn't take much sunlight coming through the curtains to turn it off.
The 555 is a pretty handy IC.
+superdau
I kind of disagree with the "overkill" part. On another breadboard I have an analog "night-rider" circuit built with 6 LED's powered through a Trip5. I have another "night-rider" circuit on an Arduino with 6 LED's also. I must admit that I prefer the analog, even though it requires more components and some nifty placement of all the diodes.
But the analog circuit just seems to be warmer, and more fluid.
Thanks for the video! When I had first started learning electronics, I messed around with 555s, but I never really understood how they worked at all (op amps were still a mystery to me). Now that I've been learning for a while, it was nice to go back and finally see how they (555s) worked and actually understand it.
Ah, my old teenage favorite IC. You can do anything with the 555. Ive even heard that some fairies can create an audiophile class A amplifier with them however, it's just rumor though. Great as always Alan. Oh, I keep hoping that I will find one of those MDO scopes laying in the street, after falling off the Tek truck. LOL Yes, I would be so glad to own one even with dents and scratches. They are some kind of scope. I'm saving my pennies.
I know the basics but I still look because I just like the way you teach them (besides that, a refresh of basics so now and then is never wrong)
10:15 "We know we're going to be charging up to two-thirds of Vcc". That's because of the three 5K resistors inside the 555 between the comparators that divide Vcc in threes, right?
+Jac Goudsmit Yup. The voltage cannot charge higher than 2/3rds at that point in the circuit, so as far as the calculations are concerned, that's out "max charge".
Very clear explanation as always. Thanks Alan!
I swear you must be related to Forest Mims, though I have learned more from you, and you are a real scientist. Thanks again. Beat EE channel on the web.
Meant BEST EE channel on the web. Please keep up the good work!
+PelDaddy No he meant Beet EE channel on the web. If you haven't watched these videos while eating a bowl of borscht, you don't know what you're missing!
P.S. Don't get any borscht on the scope or might have a red trace for one of the scope inputs...
Great video Alan!
Love your "Basics" videos! Two Questions: 1) What's the best way to connect two 555s for a "modulated carrier"? I'm never sure if I'm doing it the right way... and 2) What's the Control pin for? Any examples would be a great help.
Great video! I do however wish you'd shown us what happened if you just left the trigger input low.
I've only recently seen your ch. & subscribed....
your presentations are extremely fluent & precise...
I really like them.....In this one ,
the case of the I/p being held low / stuck low , beyond o/p p.w. ( elapsed time )was not covered.... maybe you cover it in another presentation...
Great Job! More Back to Basics Videos!
another good video. but why the pearl earring on the breadboard in the first shot?
Great video as always Alan, thanks
thanx sir could you please explain pulse width modulator used in class D amplifierincluding the comparartor (sawtooth)?
Really good video, thank you for sharing your expertise.
Fondly remember when the 555 was available at Radio Shack around the mid 70's and paying I think around $3.00 Cnd for it. Good times....
Another excellent video. Thank you. General newbie question though. Could you drive the relay directly from pin 3 (out) of the 555 instead of using the intermediate transistor?
+Bobo Johnson It depends on the relay and the drive capability of the 555. Note that it cannot swing to VCC, so this may limit the ability to properly drive a relay.
Can you explain more about the pull up resistor to VCC? Why not just connect it directly to VCC?
+DoItYourselfMusician If I tied it directly, I wouldn't have been able to momentarily lower the voltage with a simple normally-open switch like I did (that would've shorted the supply to ground.)
Thank you for that explanation. I get it now.
Great video, Thanks again..
Thanks for this good explanation.
looks like i could use this in the final stages of a bedini energizer wheel circuit. when charging batteries.
+dale myers Save your energy and money. There is no such thing as free energy.
did i say anything about free energy. you pay for what you get, from what energy it creates. and it takes energy to create what it makes... so that blows your "dumb ass" statement out of the water. till you test the theory of it's principles and prove it wrong. and you can't. because someone has beat you to it and proved it's principles and usage. just keep you food trap shut and lies wont spew freely.
Do you think Bob Widlar had any part in the design of the 555? even in an obscure form?
Doubtful. The 555 was introduced by Signetics in 1971. Bob Widlar was working at National at that time.
Amazing video!
Thank you very much!
I've been trying to get this circuit to work but when I ground pin 2 the load energizes and then just stays on. I'm getting rather determined in figuring out what I've been doing wrong. (I think I need Pre-beginner level)
Ah hah! If you hold the Trigger input low, the output will stay on. If you want the output to give the 1second pulse even if the +5v signal stays low, then you'll need to AC couple the +5v signal to the Trigger input. Keep the pull-up resistor on the Trigger input.
Why isn't there a SuperLike button?
+tomy983 Just do it Chicago style - vote early/vote often...
Won't the 555 chip drive a small relay directly?
Depends on the chip and the relay.
Hi Alan,
For some reason the notes are not showing up on this one... I get a '404'...
Cheers,
Mark
This is fixed now too, here is the updated link:
www.qsl.net/w2aew/youtube/555monostable.pdf
@@w2aew That's fantastic, Alan.
Really great channel, awesome tutorials. They are concise but complete, they unite theory with lab practice.
Thanks a lot.
Cheers
Mark
Thanks for sharing
hey dude !! I always try to get such waveforms on my CRO and it never comes. why?
A CRT based oscilloscope doesn't have the display persistence needed to display very slow or single-shot waveforms.
Thank you. That means I have to buy a digital CRO.
Can you suggest me any good company for CRO?
Thankx Sir!!!!
It all depends on how much money you want to spend. There are premium brands like Tektronix, and lots of less expensive value-based brands, plus a lot available on the used market.
K. Ohhh no!!! at least 2 years I have to work with my old CRO.
Thank you sir.
k.at
It seems you have changed something with the video quality or frame rate? It's not as smooth as your previous videos. You may have resolved this in later videos, i am slowly catching up 😊
It was TH-cam. They changed the frame rate on any videos that I uploaded in .MTS format. My originals are 30fps, but they drop it to 15fps on this format. Once I noticed that this was the reason, I changed the format to .MP4. But, there are many videos that got caught up in this change before I noticed it.
w2aew ok, I thought it might be something like that, i am now at video 244 and yes you fixed it pretty quickly. How can contact you and ask you some questions about topics for videos? I have linkedin connection requested you and tried fb messenger but to no avail 😊 I feel like i am stalking you now lol
connected on LinkedIn....
Very nice video! And that oscilloscope gave me water in my mouth, but I'm sure its more expensive than the average car :/
Can we have some quiet from the peanut gallery? ;-)
+Jac Goudsmit Ha! My wife and two of her sisters were party planning upstairs when I did this video...
I hope you can help me with this. I'm building an external flash for a digital camera. here is a link on how a flash circuit works if you don't already know: www.diyphotography.net/how-to-build-a-flash-with-an-optical-slave/
as the article said, a typical flash circuit dumps all the capacitor's energy as soon as the xenon is ionized. what I want to do is add a monostable multivibrator to pulse the energy coming from the cap so it uses less than the full charge so I can get multiple small flashes from one cap charge. I am using a 320v 220 micro farrad cap and I want it to use just 1/3rd of its full charge at a time
Hmm - I'm not sure this will work for a few reasons (but I'm not an expert on flash tubes..). The firing of the tube uses a triac (thyristor or SCR), which once triggered, continues to conduct until the current goes away. You can't turn it off once it's been triggered unless you do so with another switch type device in series with it. The other problem is that if you discharge the main cap to 2/3rd or 1/3 of it's full charge state, the voltage at the caps terminals will only be 2/3 or 1/3 of the normal flash voltage - which might not be enough to ionize the Xenon tube.
I know that it works because a lot of flashes today have red eye reduction function but still only use 1 capacitor so it has to be being pulsed. also the xenon is ionized from the trigger transformer
Ok, good to know. It's clear that I don't know that much about the drive requirements of the xenon flash tube. I can imagine maybe they replace the SCR with something else, maybe a mosfet driven by a pulsed source, which could be 555 based. Or maybe use two (or a 556) to create some gated pulses.
w2aew that's the part that I'm trying to understand. how would what you just described work? modern flashes DO use an IGBT and have components that have MOSFET.
You're basically replacing the SCR with another device (like the IGBT or MOSFET) to drive the trigger coil. Unlike the SCR with stays on once triggered, the Gate of the IGBT or MOSFET can be driven from a monostable pulse to control the amount of time that the device is on. I don't know enough about the drive requirements of the trigger coil to know how to design the details of that.
Great video. Thanks!