Classic Circuits You Should Know - LED Fader
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- เผยแพร่เมื่อ 12 พ.ค. 2024
- Classic Circuits You Should Know - LED Fader
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In this video we make an LED fader using a 555 timer, a capacitor and an NPN transistor. Change the value of the cap to change your fade time.
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Brings back more of what I thought was lost to me after a stroke thanks again paul
I really am liking these classic circuits episodes. Because they are usually simple they are cool to understand and use as a foundation to build on.
Glad I became a Patron. Love the way you teach the basics and don’t crap all over people who can only buy low cost equipment.
I love low cost gear
My 8 year old and I worked on circuit today, pumpkin tomorrow. Thanks for video.
Thank you so much for showing us this schematic and explaining how it works - it's almost exactly what I've been struggling to figure out how to do so this video has been tremendously helpful!
I do not have a background in electronics so finding out, or rather, understanding wat different parts of a PCB do and why they do it is a real challenge.
That said... what I want to build, and to which this schematic has been so helpful, includes a touch sensor, and I hope that someone will be so kind to tell me if this will work or not:
If an add a TP233 to the schematic like this: VDC goes to Vin on the TP223, GND on the TP233 goes to GND, and Signal/Out (middle pin) on the TP223 goes to both the positive side of another capacitor as well as to pin 4+8 on the 555 chip (instead of directly hooking 4+8 up to VDC). My thinking here is that triggering the touch sensor will allow the process of fading in the LED to start and that the capacitor will provide enough power for the process of fading out the LED to complete (assuming that the touch sensor was not triggered long enough for 1 full cycle).
Will this help with: Allowing 1 full fade in + fade out of the LED with only a brief 'push' of the touch sensor?
I love it when you build circuits and I can recreate it in tinkercad and it works.
This is pretty cool. Simple and effective. Thanks for the video!
I like this for the simplicity and practicality. I may use this for my fall LED door hanging wreath (which I already electronically modified)...I like the effect.
Cool, I enjoyed this video. It reminds me of my Vo-Tech electronics class back in the early 90's. We had a blast building these type of breadboard circuits. Now subbed!
This is excellent. I liked the explanation you gave while showing the schematic!
This is great. Thank you for it. Will definitely have one in the pumpkin this year. Also think I’ll make something similar for Christmas maybe something that oscillates between red and green leds.
Thanks again. Love these simple circuits.
Thanks for the video Paul! Ya gotta love that 555 for some Halloween fun!
LLAP
Awesome little project. Thanks, Paul
thank you for showing that this is possible with the 2222 , everyone else uses the bc547 or 548 (which i didnt buy a thousand of). : ) great channel
Good foundation circuit for kids. A neat idea for the coming event. Great idea Paul!
Excellent video and circuit! My humble thanks.
I like it. Nice EZ project.
Hang on a minute, if I put a .1uf cap on instead so it creates a tone through a speaker, I got myself a saw wave.
Awesome, cheers for the videos.
Love your videos! I’ve been having trouble learning how to use laser diodes and they’re requirement of a constant current source. Hopefully you can make a basics video for that topic. Thanks and kudos from Texas!🤘🏼🤘🏼
I always enjoy a 555 video, the chip that is everywhere.great project idea Paul, love the video man.
Thanks
Mr. Paul thankyou.
Sery good project. learnt from you.
That was a nice dimming circuit! Hope to see more interesting circuits, thanks.
You know I have an entire I'm playlist of these types of circuits. It's called "classic circuits" check it out
@@learnelectronics Yeah, I am going through that. Please do include a list of radio projects too. Here a licensed amateur radio operator with callsign VU2LVJ, interested in radio projects.
Good fun, and for once a circuit I had all the parts for haha! The lady of the house is preparing to pumpkin pimp the place so she was pleased to see this roll off my bench. I quite like the ominous pulse from a 330 or 470μF cap. Almost there Paul, 96.9k subs!
Glad the boss was pleased. As they say" "Aint Mama happy, aint nobody happy"
Have a great weekend!
Awesome lil circuit will give this one a go. Not to intimidating and easy to find parts. Happy Spooptober!
Great idea!
Quick down and not so dirty. I like it.
Thanks
Fun circuit Paul;)
Hi, Thank you for this informative video and circuit. I have built it as per your schematic but am having a slight issue. When the LEDs fade in and then out, on the out after about 2-3 seconds, the LEDs blink. I'm running off 5v, but had tried with 9v and the blink is there but brighter. Is there anything that can be done to remove this blink? Also what is the voltage value on your 1000uf cap, I wonder if that might be my issue? Any help on this would be very much appreciated. Thank you
Good circuit.
very nice project. But I want more leds in this manner to light up, about 18 alltogether. Is this going to work this way? It's for lighting up my miniature tank, so I have to take 4 CR2032 or maybe a little bigger to get it into the model as source. I put this circuit into ltspice and it shows me for every led more a lower curve in voltage, so I'm not sure. Thanks for support.
These videos are a very good review from my college days, and you're a much better teacher than those we had.
Just wonderig... why the weird capacitor symbol and (obsolete?) resistor rectangle symbol in this video?
Awesome 😎👍
It worked! Although I did it again without the bread board and it just lights up..??
Does it not make more sense to adjust the timing using the resistor instead of the capacitor?
I'm not sure what 555 timer you are using but most of them will happily supply 20mA of current so I think you can probably loose the transistor out of the circuit.
Nice to see the basics projects :)
Keep up the good work.
The control voltage is pin 5. I think you meant trigger (pin 2) and threshold (pin 6). I got excited and thought you might have been doing some kind of pulse-frequency modulation using the v_control pin for a few seconds.
@learnelectronics Hi Paul, Merry Christmas.
Why is the load on the emitter as most circuits put the load on the collector, and how come you only need 100 ohms when Vs - Vf / If would typically be about 7mA for 9 volts?
Nice
Thank you so much! You taught me something very useful.
Amazing video, I love these thank you so much, by the way is that a 100 ohm or 100k ohm resistor, I'm a bit confused.
100R
@@learnelectronics thank you!
Thank you for this video. What is the formula for the frequency ?
Can I reference you in my next video?
does it work with mosfet?
good video
Hi, Thanks for the circuit. I have it already working! It was a nice treat... However, ever since I am trying to wrap my mind around the unusual configuration of the 555. Bear with me, I am no expert in electronics. But so far I have seen astable circuits done much differently. Could you, please, explain a little bit? I get that Trigger and Threshold (pins 2 and 6) are connected together and to the capacitor. This is standard. But normally, the capacitor is being charged from Vcc (through resistors) and discharged through pin 7 (discharge). Here, it seems pin 3 (output) feeds the capacitor and it is must be discharged through the transistor. I tried and it does not work without the transistor so that must do some magic. However, my ignorance kicks in here. Anyone can point me to an explanation? Thanks in advance!
how does the transistor function here. as a variable resistor? how can i find out the resistance for a given base voltage? transistors are like black magic to me lol
where do the test probes go? How do you adjust the time scale for the Oscope? Thanks.
You can see that rolling curve trace by probing across the LED. If you probe the positive side of the capacitor you should get a sawtooth form. You'll need a slow timebase, about 1s/div.
Fun project. Seems there is no limit to the tricks and treats a 555 can provide.
Indeed; it can even be used as a Class-D audio amplifier! www.homemade-circuits.com/class-d-amplifier-circuit-using-ic-555/
All set for Halloween 😂
An interesting side project would be to do the same circuit, but at both extremes, completely descrete at one end, and an Arduino at the other!
Yeah buddy, Happy Holloween.
I really enjoy these videos! My wife thinks I’m a nerd but who cares !
Could you please simulate this circuit using Multisim?
I've a question for you, do you know where to source hexadecimal common-cathode display driver DIL IC's, I bought some DM9368 chips on eBay and they seem to be faked, they decode decimal but not hexadecimal, they just go blank at 1010 and above.
Or can you suggest a chip that can drive 6 X 7segment digits in hexadecimal
No sorry
Funny…. I was literally making this exact circuit for the exact same reason and I looked up “fading LED 555 timer” to see if I can find a video explaining the calculations so I can calculate the fading effect more precisely, and I run into a video that’s explaining it for the same idea I had
Don't know what I did wrong,but when I do this circuit I get a pulse instead of fade effect. When I hooked it up to my scope it shows that capacitor is charging quickier than discharging
FYI in future videos, the configuration you had of breadboard, o-scope and overhead lights put a lot of reflection onto the scope screen making it difficult to see the traces
So I could replicate that circuit say x3 on the same breadboard with varying caps and achieve sort of an oscillating of different colors?
I imagine you could, but doing so on the same breadboard is going to introduce some coupling.
@@learnelectronics Thanks for that. I was thinking that at that level the undesired transfer would be limited. You're brilliant, Paul. Thank you. Steve.
Can you make the same effect with a 3v button battery ? I want to make a very light project with the same effect
You'd want to use a 7555 CMOS timer IC; it can go down to 2V supply voltage and uses much less power.
You could also use an attiny series, fade using pwm and maybe have it 'sleep' during the daytime. A touch more than a classic circuit but fun to build :)
Can I add additional LEDs to make for a brighter pumpkin?
Thanks Paul, have a great week.
Sure
As he answered, yes.
But you've to recalculate the resistor between the transistor and the LED/S and check the maximum current for your transistor as the TO92 (body)
transistor usually handles about 100mA (0,1A) Milli Amperes, which are will be about five LED'S if you give them 20mA each which is the typical type, but they will start to glow at a few mA.
I think I would have configured the transistor as a voltage controlled current source, taking the output from the collector.
A more efficient solution would be to configure a dual 555 as a pulse width modulator, this would make best use of battery power.
A quad Schmitt can be configured as a flame simulator driving red and yellow LEDs with a pseudorandom oscillation. The same can be done with a binary ripple counter, such as the HC4060, which has a built in oscillator, that works with a RC network.
With such a long delay possible, it can be made to flicker and go out and then flicker again.
Thinking about it a quad Schmitt has sufficient gates to be configured as both a dimmer and a flasher at the same time, but then you know the quad Schmitt is one of my favourite ICs.
@Kevin Counihan it makes more sense to drive a group of LEDs from a constant current source, as the light output from LEDs is proportional to current. In the case of this circuit, it is the led series resistor that is converting voltage to current, but the test of any circuit is; does it meet the requirement spec, if it does, it works.
The flasher circuit is a different circuit with a different requirement specification. There are flickering LEDs on the market which would offer the simplest solution, but these would not allow the colour or brightness of the resulting light to be set.
In practice a single Schmitt gate can generate the capacitor charge discharge waveform. A quad pack, therefore offers the ability to not only generate the dimmer light effect, but also leaves three gates free to provide other effects, such as flashing lights or a cadence on the dimming.
Again a simple solution is to buy a flashing LED, but that too limits the choice of colour and brightness.
If this was just about providing a Halloween effect, one of the previous videos showed a circuit that flashed LEDs and produced appropriate sounds. There are many ways to produce a saw tooth waveform, each has its advantages and drawbacks, it really depends on what is in the requirement spec, in terms of cost, component count, functionality and flexibility.
@Kevin Counihanstrictly speaking, the transistor, as an emitter follower is acting as a voltage impedance converter. Buffering the RC network from the LED. It is the resistor in series with the LED that is defining the LED current.
The difference between driving constant current or constant voltage is which makes best use of the full range of the saw tooth waveform, to give maximum change in brightness. The LED introduces a fix bias offset and the position of the resistor adds to this offset, then the Vbe of the transistor adds to this, it is therefore fortuitous that the range of the 555 output allows sufficient brightness variation.
@Kevin Counihan for someone who professes to have practiced electronics for so long, you seem to have a blind spot for circuit analysis. The LED has a fixed forward voltage. The emitter follower provides a low impedance copy of the voltage on the capacitor, therefore the current through the led series resistor is set by the difference between the two above voltages. That is a voltage to current conversion, I am surprised you did not know that. I was not implying that the circuit was not designed to work, what I am suggesting is that the DC bias voltage of the 555 output limits the design options.
And I too have fifty years of circuit design experience, but this is not shared by every reader, so an explanation is justified.
@Kevin Counihan you started this with your initial post. I have simply reacted to your comments. I made constructive comments, you elected to misinterprete them for you own reasons, and you annoyed me for that reason.
Sir on delay off delay running timer 12 v easy timer
It is not a PWM right?
It would be neat. To. Put a relay on it so the relay is on like a timer.
I want this but then with 7 or more different timed leds.
use a 555 to drive a 4017 decade counter, then have the fade-in/fade-out timing components hooked up to the (max. 10) outputs of the 4017.
Why you use NPN transistor as source? It isn't always use as current sinking device.
@Kevin Counihan I noticed that this does not work in the common emitter configuration (the capacitor never charges past 0.7 volts), but once in the common collector configuration as in the video, it works flawlessly. Does the common collector configuration drop the impedance of the base of the transistor? I believe I read that this is essentially acting as a voltage buffer. Still wrapping my head around the analog world. :)
@Kevin Counihan This is a very helpful explanation, thank you!
Thanks @Kevin Counihan for your clear explanation.
Nice halloween.
Oh....you don't need an Arduino to do this?
Nope
Don't tell that Italian guy.
This circuit is too confusing... The 555 timer pin are difficult to understand
No Pumpkins were Harmed...
Only a little
LoL :)
why is classic??😆😄