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Ditto that. I'd never heard of the the TL431 and now I'm adding it to my current project as a (no pun intended) high-accuracy constant current source (sorry *sink*, even). Fantastic!
This is the first video I have seen from this channel. I am absolutely going to be using the power cutout circuit for my battery backup that I am installing in my car for my cameras.
"ln" is the natural logarithm of log to the base e. So the predicted delay for the circuit is about 0.23 x R x C. However, it doesn't take into account the current going into the Ref pin, although that's just a few microamps, but it means you can't have arbitrarily large values of R I'd suggest an upper limit of around 220K. Also, many large electrolytics are notoriously poor in their tolerances and you shouldn't be too surprised if a capacitor marked 1,000 microfarads had an actual capacitance of anywhere between 500 and 2,000 microfarads. They are also leaky, so that also limits the maximum value of the resistance. You're often best finding a good RC combination by trial and error for any given circuit.
IF NEW-BE'S ARE LOOKING FOR ONE/SOME OF THESE YOU WILL FIND THEM ON THE SECONDARY OF NEARLY EVERY PSU IN CONJUNCTION WITH THE OPTO-COUPLER, OR FEEDBACK PART ON THE BOARD, ITS THE SMALL LITTLE SMD TRANSISTOR LOOKING DEVISE WITH NEARLY ALWAYS THE NUMBERS ON IT. 431
It’s a copycat of the Great Scott channel. You even copied the « let’s get started », then German accent, the highlighters, and even this specific subject
9:30 didn't analyze it yet, but that circuit doesn't appear to implement any hysteresis. As you approach the cutoff voltage slowly (like with a discharging battery) the MOSFET gate source voltage will drop linearly and your MOSFET will enter a region where itends up biased in a linear region. It might also start oscillating with the ESR of the battery and load current draw and stuff. For UVP, you need to add some hysteresis or positive feedback so that it cuts power off decisively, and only cut power on again once supply voltage goes above some slightly higher voltage threshold. (for the record, this can also oscillate as a relaxation oscillator as the voltage on a battery could rise up with no load)
It relies on the very sharp transition of the TL431 from on to off as the voltage applied to its Ref pin passes below its internal reference, as it is effectively an amplifier with a large open-loop gain. Nevertheless, I would share your concern about the possibility of oscillations given the stray capacitances inherent in this sort of design. Adding a resistor of about 27K from the drain of the MOSFET to the Ref pin of the TL431 would add about 100mV of hysteresis, but of course could still provoke oscillations if too much capacitance were present at the Ref pin.
I like your bench. Makes for a nice background when you're explaining things. Great video and packed with so much educational content. I always enjoy watching videos on basic components even if I don't have a project to use them.
Brackets can be helpful. eg Ik = (12v-2.5v)/330 also at 9:17 Vcut is the battery voltage so voltage divider step Vr2 = Vref = Vcut(R2/(R2 + R1)) rearange for Vcut including brackets Vcut = Vref (R1/R2 + 1).That might be easier to follow for some people. Plus R3 in undervoltage circuit was not explained. Also it would be better to include feedback for hysteresis. But great video.
Nice TL431 circuit compilation. 👍 Of course not all designs was mentioned - I know few others, but I never thought about using TL431 as delay timer - that makes sense. 😉
I remember a TL431 contest a very long time ago, the winning project was an audio amplifier for a crystal radio. I suppose with enough of them, you could build a computer.
Thanks for this video sir, but what will you recommend that I make use of to understand how some of these basic circuits and how they work just like you do 😊 because I'm quite certain that you may not be able to do videos to explain all of them. I really want to know how a 3.7v auto cut off charger works using TL431 zener diode. Thanks sir for your anticipated response.
For the battery balancer, please insert a resistor (say 220 or 470 ohms) between the TL431's cathode and the transistors base to limit the TL431's current.
You are always the best at explaining things to the depth, i really appreciate your videos and recommend it not only for enthusiasts like me but for all age groups to learn something more, b'caus science and electronics has no limit.
Thanks. I did indeed learn from this video something new. You have tremendous way of training and presentation. A quick question: what advantage(s) do I get if I join your cannel and pay the subscription fees? Thanks for explaining. Enjoy your weekend
Thanks for your comment. Well, first of all you support my work and each tier has something. Usually, I post the video on the members tab days before the release so you get to see that first. Some behind the camera, download files, ect, only for members. Nothing fancy...
I have a function on an esp32 that's actuated by connecting a pin to ground. I'm doing this with a button right now. How can we replace the button with the 3.3V ouput of a voice recog module?
Perfect explanation thank you. Can you please make a video on using the TL431 as a cutoff device for battery protection. There are some videos but they do not work exactly as mentioned.
This channel deserves a lot of attention. Simple and direct, he explained much more than several Electronics classes. ❤❤❤❤ Thanks ! ❤❤❤❤ ( From Brasil ! 🇧🇷🌻🇧🇷🌻)
I wonder if you can also use it for following- -having a capacitor bank charge up from solar and trigger a circuit when it reaches a certain voltage, like solar toy. ( I imagine using a transistor and an SRC) -"reverse delay", like for electro-optic gun sight...vibration sensor senses user moving the gun, turns the sights on for a short time. (by altering the delay circuit)
The time delay circuit can be further improved to actually continue switching states, in other words a TL431 can actually be an oscillator, a peak detect or rc timing circuit can be connected the output where the LED is connected which turns on transistor (preferably a fet) that will actually be able to essentially replace the switch, for instant reset no rc or peak detector is used. For a time delay between the time the output goes high can be achieved by using an rc comparable (possibly another TL431 which will actually make it stay on for a predetermined time and stay off for a predetermined time, potentiometers can be used in both places to change both of those timing intervals independently!
Hii Electronoobs is my best electronics teacher, I am your best supporter and also a student, it was such a great content of constant current and more i learned in this video Really thanks to you🙏😅🙂 Wow you are my best always🤤
This week I made a 4 cell battery balance shunt. It turned out to be virtually identical to the circuit you presented. Good to know my brain is still functioning since I designed my circuit based on the datasheet. Incidentally, my battery is 2 modules from a Nissan LEAF running into a 1kW inverter, as a backup in case of power failure. The battery is maintained by a 5 Watt solar panel sitting in the window and only supplies 300mA at best. Incase of actually being used and needing to be recharged I'll use a bench power supply when the power is back on.
Thank you for your good job done. Please how can i use the TL431 to bring down any voltage from 35 or 40 volts to 4.5 or 10 volts with variable resistor ????
I found out about these by looking up some stuff I found in an old dvd player on guitar forums, I found a few threads where people were suggesting basically using it in place of a transitor, but what I think is more interesting is its variable diode ability. Since diodes clip signals at different voltages you probably could control how much it clips with a potentiometer, or put a regular diode one way and one of these the other way and control the symmetry of clipping with a pot. Nuts
it is interesting device..but i'm more interested how to make stable voltage with zener .if that is even possible..because even in this video you could see that voltage was moving up or down....by moving input voltage..this might seem ..ok ..if it is 2.500 or 2.515V ..but it isn't same if it is 14.5V or 15.0V ..that is huge difference..and when you need same volatage with minimal change even if input will change few volts..that is what i'm looking for ..and ofc stable with temperature..
The TL431 has a typical dynamic impedance of 0.15 ohm across the range of 1mA to 100mA, which is orders of magnitude better than a zener, and it is also temperature compensated, unlike a zener. If you're using a simple shunt regulator circuit to supply 15V from a supply that might vary between 20V and 25V, you might use a dropper resistor of at least 100 ohm. That would result in 100mA passing at 25V supply and 50mA at 20V supply. The 50mA change in current should result in a change of output voltage of about 50mA x 0.15 ohm = 7.5mV which is pretty good. Compare that with a linear regulator like the LM7815 which has a line regulation of 0.01% / V which also equals 7.5mV for a 5V change in supply voltage - but that's specified at 1A current into the load. You don't say how much current you want to draw from your stable voltage or whether you need low noise on the line, so it's hard to suggest whether a switch-mode module, a linear regulator or a shunt regulator would be suitable. The first is the most efficient but is noisy, the last is least efficient and limited in the current it can supply.
@@RexxSchneider Hello friend. I need precision voltage source with about 17V-19V (exact vaule isn't so important) my output current is about 50-80mA but typical about 30mA ..I plan to use something such as LM317 with LM399((heated zener) and OPAMP OPA177 (or similar) as voltage source for LM317(middle pin) OPAMP will be used to monitor output Voltage of LM317 so it will keep constant Voltage all the time. and at the output i will use capacitor multiplier this will reduce output voltage(and more importantly reduce output ripple) to about 15V. (exact Voltage isn't important) ..I need only same voltage even with change of input voltage of with temperature . This will be used as Source voltage for Voltage source with LTZ 1000A (about 7V in output) and later one with buffer to about 10V. Any suggestions are welcome friend.
“Hello friend, welcome back “ :) Please can you create a video tutorial on how to design a circuit in EasyEda or eggle, because there so many things I don’t understand I end up using veroboards. A good example circuit will be a high frequency inverter (oscillator part and power part, ) from drawing to converting into pcb. That way, many we’ll manage to order those pcb using your links as a way to support the channel too. Greetings from Tanzania 🇹🇿
The (only) special thing about the 741 was that it had an integrated compensation capacitor. The capacitor placed across a common emitter intermediate stage introduces an early pole that rolls off the gain at 10Hz or so if I remember right.This way, the opamp will be stable even at unity gain, at the cost of limited GBP (gain bandwidth product). The inclusion of the capacitor means that engineers and designers can use them willy nilly and not have to bother with figuring out what value compensation capacitor to make a circuit stable. This made this opamp incredibly popular as even engineers and designers are lazy, and the 741 performed well enough for most applications! The compensation capacitor introduces another problem though: Now the large signal behavior is limited, manifesting as a slew rate limit. Slew rate is the derivative equivalent of over-driving an amplifier. Just like how too much input amplitude and gain can result in clipping, a signal that swings too fast also get "clipped" to some maximum voltage swing or dv/dt. The 741 is a pretty slow opamp that can only achieve a few volts per microsecond slew rates. Really ultra-low low power opamps, especially older ones, had really pathetic slew rates!
@@power-max No so much special and an industry standard, no? I read with some hilarity how many mixing desks were "powered" by 741s and yet audiophiles spend untold thousands on equipment to get the best sound possible. I'm sure most of those old desks have been replaced with something far better, perhaps 5532s or better, but those old tape master recordings will still have 741 audio all over them. ;)
@@marcdraco2189 Sorry I am not in the know with all the audiofoolery stuff. What I can say is that the 741 is a pretty shitty opamp in most respects. It is slow (0.3 to 0.7V/μs actually), GBP is meh (1MHz), it is noisy as hell, input impedance isn't very high, and is far from being any good for single rail operation. (Output can only get within 1.2V of either rail in the best of times) and the inputs do not work near the supply rails either. Specs were above average back when it came out, the internal compensation was the real selling feature for them.
@@power-max Completely agree with you. It's a terrible op amp, the other standard 555 wasn't as awful in real terms as it solved a lot of problems. I think the joke (serious as it is) with the mixing desks is that so many were allegedly fitted with 741s in critical signal paths and I don't need to explain to you what that means! When I was learning, the 741 was everywhere in the magazines and reference books. The big names like Ray Marston and others pegged it as their jellybean of choice. This is the days before the Internet. I often chuckle to think how we coped back then! Paul Horowitz and Winfield Hill suggest the 411 as their jellybean and it's certainly better so far as I can tell. There's a lot to be said for picking an amp according to the application. I'm currently using something TL074 in (test) circuit because it has such poor GBP. It's hilarious to see how a lovely sine wave at 20KHz degrades to a triangle wave by 100KHz (losing a good 6db on the way). It's a lazy way to avoid filtering the HF noise which the 5532 passes it beautifully... LOL. This is a breadboard so when it goes on a PCB I can concentrate on the EMF issues and use a simple 2 pole Sallen-Key filter should that become necessary, but I doubt it will.
@@marcdraco2189 the test with a sine wave turning into a triangle wave, that is actually not a result of GBP. That is slew rate limitation, caused by the internal compensation capacitor and low bias current of the first long tailed pair. Slew rate is a large signal effect so to work around it try reducing your signal amplitude. Oh and I had a real interesting issue with a sallen key filter when I made one with a LM324. I observed that high frequency PWM noise was getting through. The filter wasn't filtering as good as I was expecting from simulation. Turned out the LM324 has limited output current source but can sink a reasonable amount. The issue was with the capacitive loading on the output from the filter stages. Solved it by adding a lowish value pull-up resistor so as to bias the output so that only the bottom transistor conducts. (Bring it from class B to class A operation, if you will). Yeah turns out some op amps really don't handle capacitive loading well. I think W2EAW covers this in one of his videos.
