Astable multivibrator demo circuit w NPN 2n2222 and capacitors explained by electronzap
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- เผยแพร่เมื่อ 11 ก.ย. 2024
- / electronzap
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/ electronzap
/ electronzap I now do my gaming, Fallout 4 for the time being, on Twitch.
I explain much of what is going on in the astable multivibratior circuit.
th-cam.com/users/electronzap. Donate if you can to www.patreon.com/electronzap and check out products I use in my videos or would buy at www.amazon.com/shop/electronzapdotcom. As an Amazon affiliate I earn from qualifying purchases.
This video explained to me everything in a very simple manner that no other video or article could. Thanks
Great to hear! Thanks for watching!
Wow this is by far the most thorough explanation of a multivibrator circuit I have seen on the internet. Thank you!
Glad to hear! Thanks for watching!
Yeah it really was!
so nice this vid wasn't in hindi. I loved the explanation.
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Thanks a lot! It worked flawlessly!
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This video rocks! One of the best videos I've seen on this multivibrator circuit!
Glad to hear, thanks for watching!
Thank you. I've made these on breadboards out of books but, couldn't get it. Now I got it!😊
Glad to hear, thanks for watching!
Finally able to get a square wave after using your schematic. I tried a few different ones. Not sure what the problem was, but after seeing your drawing, taking everything out of the breadboard and putting them back in, finally saw it oscillate :).
Glad to hear!
I made this with this video, worked just fine
Glad to hear thanks for watching!
You are using a bipolar capacitor with its negative towards the base of BJT?
Plus when the cap charges, its negative side is fed by positive voltage with the 10K resistor.
When the left bjt is on, the voltage on its collector drops to 0 basically. It measn that the positive side of that cap ( to the left) drops to 0 while on the right, the negative side of the cap will be at 10V+. No?
In other words those caps are getting charged by the base circuit that is connected to the positive rail and not by the collector low ohm resistor at anytime.
Thank you so much sir. ❤️
Thank you!
Great ,I don't know how but everything I decided to make you already have made years ago 🙃🤭.
Great work
Happens lol
I have a number of beginner electronics books and they all use bipolar transistors in the astable multivibrator build. So I looked up youtube videos about the same topic and they all use bipolar transistors. So why does everyone use them? Why not use mosfets or I.G.B.T.s or is there a reason why they are never used?
I made mine because it was in books, other than that I picked the component values. I don't know if other transistors will work. You can always do google searches for different transistors and astable to see if anyone shared a circuit. It's easier to just wire a 555 timer in astable mode than to use transistors anyways, so probably not much desire to design astable transistors circuits.
I love learning about electronics from norm macdonald
Glad to hear! Thanks for watching!
Thank u😘😘😘...i had so much problem with this circuit...u just made my day😍❤😍❤
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How does it decide which side to start from? 😂 Great video. Is there a chance that the capacitor well will be reversed polarity?
Not sure lol, probably slight variations in the components actual values will make it favor one side over the other when it comes to starting.
@@Electronzap If it has to do with variations in the components (which makes sense) the same side will always win right?
awsome thanks
Thanks for watching!
You saved my life man, the only question I have is why did you select those specific resistors? What is their purpose? Subbed btw
Glad to hear and thanks! The resistors in series with the LEDs have to limit current to an amount safe for the LEDs (no more than 20mA), the resistors themselves (no mare than 1/4 watt, preferable to be no more than 1/8 watt), and the transistor (hundreds of mA), but still provide enough current to light the LEDs to a bright enough level. The 2 resistors that go to the base of the transistors mostly control how fast the capacitors charge and discharge based on their capacitance. It also takes very low current to turn a transistor on. so it's OK that they are higher value resistors but can't be too high.
@@Electronzap ah ok gotcha, so from my understanding, when the transistor on the RIGHT is ON, one led is on and the capacitor above CANNOT charge due to negative electrons flooding into the positive and the capacitor on the LEFT IS charging because the transistor on the LEFT is off which forces the cap above it to not loose charge and the transistor on the right is also connecting it to ground thus completing its circuit. Then the voltage of the base of the transistor to the LEFT starts to build up until its high enough to open/opens due to the capacitor on the RIGHT not being able to suck charge in away from it due to the transistor on the right making it unable to hold a charge. When the capacitor on the LEFT is full it then discharges and by doing so turns the transistor on the right off by making its base more negatively charged/turns off a led and also discharges itself through the transistor on the LEFT becuase it had just been opened a sec ago, and at the same time connects ground to the capacitor on the RIGHT, thus it is able to charge by completing its circuit all while a led is on on a different side now. Voltage is now starting to build up on the base pin of the transistor on the RIGHT. Then when the capacitor on the RIGHT is done charging, it releases its negative charge which is connected to the transistor on the LEFT base pin thus closing it/turning off a led and shortly after the voltage has built up enough on the transistor on the RIGHT base pin that now it can open and start the whole process all over again.Made left and right bigger just in case someone reading gets lost :p
I made this video later on when I had more time. I drew out and explained how I see the current paths flowing in this circuit th-cam.com/video/zTb9JSY3rec/w-d-xo.html . I also just posted the diagram to my Patreon page www.patreon.com/posts/28133369 . Hope you enjoy!
Thank GOD 😇and thank you very much 😉Since both sides of the circuit are equally 🤔 How do you know which LED will respond (blink) first 🙄
You probably won't know which LED will be first to light, but I'm sure differences in components will make it so some circuits have one that starts all the time, while other ones have the other LED start at times. Thanks for watching!
@@Electronzap I was thinking the same 🤔 So I am going to build 2 circuits 🙂One with your 'numbers' and 1with 1side the same as yours 🤔 but the other side with a 25% value difference 😎 Do ANYBODY know how I can display this to a VGA monitor 🤔and print the results 🙄Let me know 🙂
@@Electronzap That's one way I see proving the hypothesis 🙄
Sounds fun!
hello sir,
I have made Astable multivibrator from Transformerless power supply which gets an output of 12v & 40mA, it works well 24 x 7 but after few days Transistor stops working
and only one LED lights (without blinking), why is this happening ? Please reply.
No clue lol, probably too much current (maybe even voltage) somewhere for some component. Most LEDs like the one I use are rated for only about 20mA of maximum continuous current and will have shorter life or instantly destroyed with higher current. An accidently inserted backward polarized capacitor may short circuit at some point. Voltage spike from unregulated AC to DC power supply could zap a semiconductor easily. Miswiring the pins of a transistor may let it operate rather normally for a period of time and then burn out. I could go on forever, need to check the wiring and datasheets of all components involved to see their limitations. Good luck!
so can you tell me how much current is required by 2N3904, 2N2222 transistors, As in this video you have mentioned 9Volts but how much current you have provided to this circuit?
The most current going through here is ::approximately:: 9V power source, subtracting 1.5V from that for the LED voltage drop for 7.5V (9V - 1.5V = 7.5V) which is across the 1KΩ resistor 7.5/1000=7.5mA going through a saturated transistor.
my lights need 9V, i dont know how to achieve that :(
why all LED Negative terminal connected to (+) positive volt ?
The LED is hooked up right. The long lead (anode) goes to (+); the short lead (cathode) goes to the (-) see
en.wikipedia.org/wiki/LED_circuit
The way I think of it is the arrow on the symbol points to (-)
I love you maaaaaaaaaaaaaaan
I don't believe it is amplifying?
Transistors take a low power signal and use it and a power supply to provide more power to something else.
@@Electronzap - I gotcha.....but the collector current is not itself, magnified? It is simply allowed through the transistor from collector to emitter? Im a newer student, so any elaboration appreciated?!? (Your right I'm sure, just curious!)
Yeah, the main property of a bipolar junction transistor (BJT) is that a small base to emitter current allows a larger flow of current from collector to emitter. So the output current/voltage is often higher than what you input. All the BJT itself is ultimately doing though is controlling how much power is being delivered by a power supply to some other circuitry. It's confusing at first, but after you build some simple circuits and study what they are doing, it is not so bad :)
How about amplifying electrical sound waves from a mic for instance? A sound wave isn't on or off, its amplitude needs to be amplified proportionally. Does such application requires different types of transistors?
Don't trigger npn 2N2222 WITH 9V
why not?
there is a resistor!
A 2N2222 will saturate and not switch. Us a 2N3904 instead.
Question.
SHORT VERSION: I have made a similar project and when I started measuring the voltage across the capacitor with the multimeter when the LED "on the side" of said capacitor turned on it's values gradually dropped like from +5.1V, across +3V down to +1V and I thought it will stop at 0, but NO it went to a negative -0.3V. Checked the other capacitor, same thing, many times. Why?
LONG VERSION/DETAILS:
I have made this (well I hope exactly this, because I have made mine using a guide of a Turkish (?) TH-camr th-cam.com/video/8zivwsTA2rw/w-d-xo.html I did not understand a thing what he said but it seemed easy to follow.). Some differences: 320 Ohm resistors "at the sides", 10 kOhm resistors "at the center", and originally two 100 uF capacitors which I changed to 1000 uF capacitors in order to observe things better in "slow motion" (which allowed me seeing both LEDs practically being on at the same time, but one getting gradually dimmer and making measurements). P.S. the Turkish (?) guy's annotations seem to say he mixed up the capacitor polarity in his chart, so if you try to build that keep this in mind - I seemed to follow only what I saw in the video and no capacitors blew: it was a bit scary to connect the battery for the first time though lol.
🤍
Thanks for watching!