RGB dimmer teardown and schematic (no microcontroller)

This must be the first time I've ever referred to the humble 555 as a microcontroller. To be fair, it does have 8 pins and runs at 5V. Maybe a few less transistors though.
Huge processing-power errors aside, this is an interesting and different use of the 555 from normal.
It doesn't use the main output pin, but instead uses the standard configuration to provide a triangular waveform directly from the capacitor.
This is a very retro circuit, but it works well and is fully serviceable at every level, with scope for customisation in terms of PWM frequency and potentiometer range.
The search keywords to find these on eBay are - rgb knob dimmer
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#ElectronicsCreators

[@Zerbey]

I used a 555 as the basis for my final GCSE project, was an egg timer and worked first time much to my own amazement. Amazing that they're still using this very versatile chip.

[@bigclivedotcom]

The 555 still appears in a surprising range of commercial products. Like street lighting dusk sensors as a threshold operated relay driver.

[@Zerbey]

@@bigclivedotcom I'm starting to get back into electronics tinkering, maybe I'll do a 555 project and relive my glory days.

[@wimwiddershins]

Ive worked with little kids. I made a few colour mixers as part of a STEM learning program. Some kids really get into the implications of it, beyond just the pretty lights, good for identifying future members of the technical family. :)

[@redoverdrivetheunstoppable4637]

and strangling em?

[@sofa-lofa4241]

I appreciate the OP's comment about teaching a bunch of kids about colour mixing and being able to pick out possible future coders, electrical engineers, mechanical engineers from such 'hands on' lessons, I think STEM learning can be great for identifying future engineers...it would be such a shame if they ended up flipping burgers for McSlopp & Co. I did 'Machine shop' at secondary school in the 80's, I'm sure that mills/lathes/drill presses, etc. are probably not a thing for 11 year old kids these days... Too dangerous! That machine shop teacher got me and a couple of other kids a place at the local technical college to learn machine shop, welding and electrical/electronics engineering, He placed around 4 or 5 kids every year, I was there from aged 14 to 16, it got me a City & Guilds in engineering at aged 16... A great bonus at job interviews and it got me a job at a precision engineering factory within 3 days of leaving school, Please don't take the piss out of teachers that are trying to find a path in life for students, that actually suits them, I had a few good teachers at school, people that actually cared about me and my path in life, and that is something I appreciate to this day, They still exist... just in fewer numbers! Thank you Win, you have made a difference in people's lives already, I am sure

[@sofa-lofa4241]

@@nobodyelse-h6h that's your opinion... And that's fine with me... But I have seen how the education system is not fit for use, it is broken in many ways and it is only by the hard work of teachers like this that we will have any engineers in the future, Kids these days want to be sports stars, famous musicians or tik-tokkers, it's good we've got someone keeping a reality check on things... Sh*t needs fixin!

[@jaapaap123]

@@redoverdrivetheunstoppable4637 No, we strangle the non-technical ones. Or at least the psychopaths that end up in manglement.

[@redoverdrivetheunstoppable4637]

@@jaapaap123 if the video we are in would not be big Clive's channel everybody would agree on strangling em

[@Frankhe78]

I love the simplicity of this circuit. It is functional and reliable.

[@chrisa2735-h3z]

As Products should be!

[@cbcdesign001]

Yep and it will probably operate for a great many years as a result of that simplicity. I am an old school electronics engineer, never bothered learning digital, only analogue. I have circuits I designed for my own use (outside my professional industrial stuff) that have been working continuously for nearly two decades now, they just go on and on working away 24/7. Well built analogue circuits are just that reliable.

[@mmmhorsesteaks]

Love this, good old analog circuitry. Simple, elegant, doesn't need firmware updates. A breath of fresh air, almost.

[@matthehat]

I’m stealing this design. I can’t believe I didn’t think of this before. I’ve built a similar circuit before that used a comparator to generate a PWM signal from the sawtooth output of a voltage controlled oscillator. It never occurred to me that multiple comparators could be fed the same signal to generate multiple duty cycles.

[@Peter_S_]

It's fairly elegant.

[@GeneralPurposeVehicl]

I was planning something similar, but still rather different: Multiple 555s driving simple discrete amps, with overcurrent protection.

[@greenaum]

Ah, use an Arduino! It's such a simple project, it'd be a good way of learning programming. And programming microcontrollers is cool, much less bother than programming a horrible modern computer. Micros don't even HAVE an operating system! Well... they can, on some of the more complex chips, if you need one. Most people don't!

[@GeneralPurposeVehicl]

@@greenaum KISS: Keep It Simple, Stupid Simple things like these are easier to design and troubleshoot. I have a programming degree and troubleshooting even a small program can be very painful.

[@Peter_S_]

@@greenaum I have to agree with GeneralPurposeVehicl. KISS is well known for good reason. Sawtooth or triangle oscillators don't require programming, don't crash, and don't need FCC approval in a product (anything with a >8KHz oscillator does). There are hundreds of thousands of microcontrollers running my code right now (you might even own one), but I prefer this reliable analog approach for many reasons from design to manufacturing.

[@LazerLord10]

reminds me of when I made a power telemetry system for 15 channels whose only digital component was a 4 bit up-counter. Used that to sweep through an analog multiplexor that looked at 15 different scaled analog telemetry readings, with one sync pulse for timing. Fun times. Oh, and it did use a 555.

[@andreasu.3546]

I was so ready to write "I could do that with a 555", but then...

[@willyarma_uk]

That method of PWM is genius! Its so simple! Thanks for explaining it.

[@makimcleary393]

The triangular wave form goes exactly from 1/3 to 2/3 of the supply rail, because the turn on and turn off points are set by three identical resistors inside the 555 (usually 5k each). So a 1k potentiometer and the two resistors of just shy of 1k would make sense.

[@M4RC90]

That's why it is called 555 after all.

[@amojak]

@@M4RC90 not a lot of people know that :)

[@two_number_nines]

@@M4RC90 no its a coincidence, not the reason. eevblog has a video explaining it

[@chrisa2735-h3z]

The First sentence made my brain hurt😝

[@GiBBO5700]

I thought that too when Clive was guessing. 1k would make the end points slightly above and below the waveform. Gets you a 0 to 100% PWM range. Beautifully simple

[@bekar2734]

555 timer is still one of my favorite ICs.

[@bigclivedotcom]

It's actually a really useful set of internal blocks.

[@0richbike]

a classic!

[@kokodin5895]

i made one from transistors on a perfboard once when i was prototyping a circuit because i didn't have a 555 at hand it look crazy when a 7x5 cm board is sticking out of ic socket but it works

[@Tsnafu]

I've got a bag of 555's that I've never used. Could you show us some things to make with them Clive?

[@pd8559]

$4 for 100 555 chips from Aliexpress 😜

[@Nono-hk3is]

Impressive that they are using a single 555 for all three channels.

[@lwilton]

More impressive (or something) that they are using three sets of high and low resistors for the three pots. You only need a single pair of 330 ohm high and low resistors for all three 1K pots in parallel.

[@DerMarkus1982]

@@lwilton Then you'd have to triple the values of each of the three pots, since 3 times Rx in parallel equals to 1/3 Rx, which would skew the voltage divider chain. But yeah, would be doable, i guess?

[@lwilton]

@@DerMarkus1982 Nope. The current pots are 1K with 910 ohm resistors top and bottom. Three 1K's in parallel is about 333, so a single pair of 270 or 330 ohm resistors will do the trick for three 1K pots.

[@edpietila2026]

The schematic is just showing one of the outputs. You need to have 2 more to control all 3 colors. So, it’s using (3) 555’s in total, not 1.

[@DerMarkus1982]

@@edpietila2026 No. Look at the PCB. It has only one 555 timer IC, providing the "compare to" signal to all three OpAmps.

[@electr0maker436]

I use 555 timers all the time! it was the first IC that I really played with as a kid and growing engineer. My brother has had one of these units for several years, I really like it.

[@awatt]

555, the number of the electronic beast.

[@MyProjectBoxChannel]

You can't kill the 555 it's going to live forever!

[@ApplyBacon2Boobs]

The only Integrated circuit that most people can build from scratch...

[@dalenassar9152]

I had a bunch of these about 10 years (still do) and was mostly impressed with the 555 configuration. IIRC it had three 555's on board and 5k pots. THE 555 WILL NEVER DIE! ALSO, you mentioned educational uses... I built a color clock in which the colors of the LED's mixed as the rainbow (but including MAGNETA). It was a ONE-OUTPUT clock with the colors smoothly mixing acroos the spectrum. With practice, one could get at estimating the time of day from a single color-sum. I didn't know they were still around. THANKS FOR ANOTHER GREAT TEARDOWN!! --dALe

[@ForTheBirbs]

I used to have a great book full of "triple five" timer circuits. I wish it hadn't gone missing.

[@bigclivedotcom]

You can probably find it online.

[@markfergerson2145]

@@bigclivedotcom Google for "Forrest Mims 555" and you can download the PDF. Be aware that some of the circuits are incomplete "starting points", but if you carefully read the introduction you can easily fill them in.

[@cornwallonline]

I remember Babani Books did one. A long time ago, when even I was young 🤣 Mind you, I remember when Maplin advertisements were based around 'Maplin, home of London's new airport'!!!

[@AndyFletcherX31]

@@cornwallonline I had that one, the whole series looked to be printed on toilet paper! Just looked on Amazon - eye-watering price for new and over a tenner for second hand!

[@cornwallonline]

@@AndyFletcherX31 ​ @andy fletcher yes, the quality was a bit lacking! Funny how they are so expensive now - a quick search online brings up thousands of circuit ideas for 555's. Mind you, there's something more tangible about a paper book that 'online' does not provide - I'm currently hooked on the X Chapters of AoE - great bedtime reading, but still not the best quality paper!

[@tiretdu8884]

Just used a 555 in my students project and never imagined that we can use it in such a clever way, thanks Clive for the knowledge !

[@cannotbeleftblank6027]

The 555 uses potential dividers to 1/3 and 2/3 of the supply voltage to switch between loading and unloading the timing capacitor. Therefor a 1 kiloOhm potentiometer would make perfect sense because together with the 910 ohm resistors you would have a range that is just larger than the voltage swing of the capacitor, so you can go from 0 to 100%.

[@bigclivedotcom]

That makes sense. I didn't realise that the resistors in the 555's internal divider are effectively all the same value.

[@Brokkoli7hun]

@@bigclivedotcom you wont believe why it is called 555 timer ;)

[@makimcleary393]

I just wrote almost the same comment before I saw yours 😂

[@galfisk]

It's actually not called the 555 because of the three 5k internal resistors. "Although, there is a belief that this IC got its name from the three 5k resistors in its internal circuit, Hans R Camenzind revealed in his book, “Designing Analogue Chips”, that it was Signetics manager, ArtFury’s, love for the number “555”, that led to the naming of the circuit."

[@makimcleary393]

@@Brokkoli7hun I was today years old when I made the connection between the name 555 and the three 5k resistors. Facepalm 🤪

[@tomasmcmarques]

I know very little about how electronics actually work, the names of the components... But I really enjoy your videos and how you explain things. This was such a brilliantly done explanation, thanks!

[@krnlg]

Big Clive got me into electronics exactly because he explains things so well and makes things interesting even if you don't know the details! Then over time, the knowledge develops :)

[@mikescott58]

Actually, the capacitor on the 555 fluctuates between 1/3 Vcc and 2/3 Vcc based on an internal voltage divider. Surprising that they didn't use the 4th channel to control RGBW tapes.

[@ElvenSpellmaker]

I like how Clive says "achieve all the colours this tape can" as opposed to "all the colours" haha.

[@LostInTech3D]

just here to say "brown" and then disappear

[@ElvenSpellmaker]

@@LostInTech3D YES!

[@daze8410]

​@@LostInTech3D Yeah because a dark color like brown or black, or even true white, isn't really a color but is the "shade/tone" of another primary color (Black is an absence of color/light, True White is a concept and doesn't exist). To get different shades or tones, you add or remove light to an object. When you look at an object you are not seeing the color that it is, you are seeing how the light interacts with that object. You can see light because it is both a wavelength and a particle. Any brown you see from a light is just being tricked there with reference. Open up a fullscreen picture of brown and ask people what color it is lol

[@stargazer7644]

@@LostInTech3D Brown is simply dark yellow. If you don't think RGB LEDs can make brown, then tell me how your monitor is showing the color of Clive's workbench with only RGB pixels.

[@stargazer7644]

@@daze8410 "When you look at an object you are not seeing the color that it is, you are seeing how the light interacts with that object." I believe that is the very definition of color. So, yes you are seeing the color that it is.

[@ElvenSpellmaker]

Title: _"(no microcontroller) "_ Clive: _" The 555 was one of the first microcontrollers"_ . Everyone: *Pikachu face*

[@bigclivedotcom]

Yeah, that might be my best slip up in a long time.

[@ElvenSpellmaker]

@@bigclivedotcom hahaha

[@PunakiviAddikti]

That threw me for a loop as well.

[@Ascania]

Someone Somewhere (probably on the EEVBlog forum): Challenge Accepted!

[@DerMarkus1982]

I mentally replaced "microcontroller" with "integrated circuit" there. Loop evaded.

[@patchvonbraun]

I love that the 555 (a chip I met in the early 1970s) continues to live on in modern applications.

[@ChrisB257]

Takes me back! Forget exactly my first use of a 555 but it followed soon after a twin BC109 multi vibrator when I wanted something more compact - plus also often used for timing of course. Has to be one of the ubiquitous devices (741s too) from ages ago - in my case probably mid 70's or earlier. I'm old - I go back to thermionics - 6V6, 6K7, KT66, ECC82 etc and on to the heady days of OC71 and PNP germanium stuff. How things have changed - darned surface mount stuff so small it's a nightmare trying to do replacements. :)

[@Xiefux]

i actually bought this dimmer a few years back. used it to add rgb lighting to a gaming pc, drilled holes to the front of the pc to put the knobs thru. very nice rgb controller.

[@piconano]

I was sure the 78L05 required an input cap and an output cap! Usually about 0.1uf and 0.01uF respectively. This design didn't bother with the input cap, which could make the regulator oscillate in some conditions.

[@KarldorisLambley]

i particularly liked this one. 555s, op amps, and mosfets are all things that make sense to me. so it was a treat knowing what was going on. gotta love those 555 ICs.

[@bigclivedotcom]

Thanks.

[@bikkiikun]

I used to use 555 timers as dimmers before (I think there should be a comment on this somewhere very far down). I used one timer for each channel, and regardless of whether I used discrete chips (one timer each) or the 558 (four in one) chip I got nasty flickering (made worse by some resonance at certain settings), which could be toned down with lots of flitering and big caps (and pobably my circuit as crap as well). I now tried this method, with a single 555 timer to provide for a common basic wave form and multiple opamps and (digital) potentiometers... it's awesome... simple circuit no flickering whatsoever. A genious circuit. I can't give enough applause to theone who has thought about and to Clive for showing it to us.

[@GM-vk8jw]

Wow! I think I can see an RC, a voltage divider and also the building blocks of a ‘relaxation oscillator cct’. This is no longer gibberish! I am truly in debt to you Big Clive!

[@TheRailroad99]

very retro. you could easily add an opAmp adder and a low pass to modulate it with music.

[@Peter_S_]

That would be a very cool mod to this circuit! Different filters for each color and selectable polarity per color could make this a very cool little light-organ circuit!

[@GloriaTheFox]

That seems like a fun hack for this circuit

[@Lumibear.]

Oh please do and market it, I’ve soooo missed colour to frequency coordinated sound to light units, it died out around the millennia in favour of dumb preset light patterns triggered by volume spikes, and they’re just not the same.

[@TheRailroad99]

@@Lumibear. If I have some time I will experiment with a few circuits. If I have more time, I will the make a PCB Gerber file and post it here.

[@mostlymotorcycles.]

Brilliant description of how the pulse width modulation circuit operates, very interesting.

[@ThePoxun]

the use of the 555 reminded me of another unusual use which is how early PCs measured joystick positions... cutting a long story short they used the potentiometer in the joystick to alter the timing of a 555 (well they used the 558 4x package) to switch a single bit per channel and timing how long the switch took rather than do a 'normal' A2D conversion that would require at least a byte per channel.

[@jamesharmer9293]

I built a single channel version of this many years ago to control the electric motor on a remote controlled model speedboat. Didn't use the op amps though, just varied the duty cycle of the 555 with a pot and then fed the squarewave output into a pair of large mosfets. Worked a treat and because the mosfets were either on or off there was hardly any heat dissipation which made it easier to install and more battery friendly.

[@MMuraseofSandvich]

I used a super simple 555 LED dimmer circuit in a project at work, to ensure all the 12-volt white and red LED tapes got consistent brightness-- twist the trimpot on each dimmer, done. I still have the PCBs I ordered, each circuit was like 5 bucks all told; the circuits inside the project were made from perfboard though, the PCBs didn't arrive in time. I think I initially used DIP packaged 555s, then after seeing how practically indestructible they were I switched to SMD packages to make the PCB more compact. Same with the MOSFETs driving the tapes.

[@mikeselectricstuff]

Surprised they didn't use the unused op-amp do do the ramp generation instead of the 555 ( and the 78l05)

[@AndyFletcherX31]

Yeah, thought that too - would have saved BOM

[@kapioskapiopoylos7338]

when they realise this, the circuit designer is getting fired

[@markfergerson2145]

Sometimes doing that with one op amp restricts current on the chip making the others do weird things.

[@kapioskapiopoylos7338]

@@markfergerson2145 a 500Hz oscilator is not super demanding, given the other op-amp is used to drive 2 mosfets, this can easily drive 1+the ultra low frequency oscilator. what you say could be correct in say a 4 channel opamp with 3 high loads and a sensitive rf oscillator given not enough decoupling and/or voltage drop internally, and that will surely depend on the part and it will only cause a failure on a circuit that was working on its limits anyway

[@allalphazerobeta8643]

Maybe, they decided to use the 555 just to increase the demand for 555 chips to keep them in production.

[@MothKeeper]

Hi Clive, I've had a quick search through your vids and didn't find one... Soooo could you do a video on the awesome 555 showing all its features and some useful circuits please. I understand there are loads on KZbin BUT you do things in such an easy to understand way 👍👍👍

[@Peter_S_]

BigClive on the 555 and BigClive does Op Amps would likely be smash hits and could each be a mini-series covering all kinds of territory. 🏆

[@blkmgk16]

Another device my wife didn't know I needed! I've learned so much from you in a month, clive thank you so much.

[@sangeeth_619]

I wish I had teachers like you in my college... Your way of presentation is just excellent! 👍👍

[@CepheiVV]

3:42 the shh-kematic, a classic!

[@chrisa2735-h3z]

Every time I hear Big Clive’s voice: “ah yes, Quality content☺️”

[@Wtfinc]

This is probably Clives most informative video ive ever seen. I loved it and feel like I've grown 10 years in 10 mins.

[@truegret7778]

Thats very cool! Very simple old school design (K.I.S.S.). When you were talking about the OpAmp, I had flashback of memories from one of my professors that when teaching us about OpAmps, he would say "here is the data sheet of our ol' friend the 741 ...". Thanks for sharing/teaching. I might just blow the dust off my electronics bins and build this circuit.

[@77thTrombone]

_State of the Art 555 _ Whoa, what?!?!??? That chip came out 49 years ago! Gotta watch this Clivery!

[@ThunderBassistJay]

In the late 80's I designed and built something very similar to this, to control heating elements of a temperature calibration bath. The ramping voltage switched a solid state relais. Stunningly similar! 😲

[@brucewhiteside1741]

Wow. Cool PWM. And screening the unused pins

[@rfmerrill]

The resistor in series with the regulator probably serves to offload some of the power dissipation (same total voltage drop but some of it is across the resistor instead of the regulator).

[@DejitaruJin]

This actually gives me a very good idea on how to make a dimmer circuit for those "fake sunlights" made of an old LCD screen.

[@andymouse]

Wonderfully ' Old School ' wonderfully explained.....cheers.

[@pascha4527]

Thank you for taking the time to explain everything! Very easy to understand! I learn more than during school haha

[@KevinDC5]

I’ve been wanting to make myself a unit just like this because I don’t have access to my arduino ide at the moment. Almost like a visual Atari Punk Console. Passive units are much more elegant in my opinion as well. I’m pretty sure I have all the components needed to make this. I’m gonna have to give it a try tonight. Thanks for the schematic! 🤘🏼🤘🏼

[@johndododoe1411]

A triple or quadruple op-amp would save one chip. Limiting input to 12V would allow removing the 7805.

[@daze8410]

As soon as you brought up that 555 timer, I instantly knew how this worked lol. If anyone wants a more in-depth explanation of that timer you should check out Ben Eater's video on the breadboard clock module. I fully expected a rectifier, resistors, and a couple capacitors..... Didn't expect a pot to run PWM'd LEDs!

[@stridermt2k]

Wow that is old school and yeah modifiable! Nice!

[@Nono-hk3is]

Thank you Clive!

[@HagarVikin]

Clive really like the way you explain things it make a lot of sense better than half my lecturer's ... enjoy over a cooper pale ale cheers :D : D :~

[@0Light6and3documentary9]

Super, thank you video the rgb led lighting

[@DerMarkus1982]

A Dimmer? No MCU, Just a 555 Timer chip? Oh, a "manual" PWM circuit! Love it!

[@chrisengland5523]

An interesting and excellent circuit - well thought out and unexpectedly only one 555 is needed. I've just completed the design of a dimmer using a 555 and MOSFET, which is adapted from the circuit of a standard buck regulator. Why the complication? Well, the load is a set of 6 SES E14 Bonlux 2 watt LED lamps (see Amazon) that are advertised as 'non-dimmable'. They work on any voltage between 12 and 24 volts, either ac or dc. A PWM feed doesn't work with them because they obviously contain a capacitor that can grab all the charge it needs in a short time, so even if the PWM signal is mostly off, the lamps still operate at full brightness. (This is presumably designed to bridge the gaps when used on 50 hz ac.) The 555 produces a variable PWM signal, controlled by a potentiometer, at about 500 hz., which feeds the adapted buck regulator to produce a variable dc voltage (with a little ripple, which is fine) and the lamps dim nicely with no flicker. Everything is fed from a 12 volt supply, since I don't like mains in the garden. I could have used a variable linear regulator, but I wanted to keep the efficiency high.

[@henricomonterosa4534]

Wow, so cool. I will add this to my circuits that i can let the interns build and learn on if i may 😊

[@spiderplant]

I've never actually seen one of these!!!!! A friend and I literally spent months "inventing" one because I've never actually seen one being sold!

[@d.t.4523]

Cool little arrangement! Great idea to work on other 555 circuit ideas. Thanks. 👍

[@MyProjectBoxChannel]

years ago I've built a circuit similar to this using a LM324 quad op amp. One of the opamps was used as a oscillator /ramp generator, and the other three were used as comparators.

[@Dwdanieldotdd]

I could see you switching the output of the 555 out for an audio input giving you an adjustable color organ effect. That would be very Clive of you.😂👍😎Take care. Tootles... Wade

[@Myth_Incarnate]

An elegant solution from a more civilized time. Makes me start dreaming up robotic toys with little variable resistor knobs as the controls. :B

[@hadireg]

one moment pleaase... ! Love those moments 😀🍺 Cheers mate! Once explained this circuit is pretty simple indeed.

[@janhumpolicek8373]

This is amazing....... so lets take it to bits!

[@videolabguy]

The built in thresholds of the 555 are 1/3VCC and 2/3VCC. Thus the resistor stack is roughly 1K/1K(pot)/1K. This makes the top of the pot 2/3VCC (roughly) and the bottom 1/3VCC to match the range of the triangle wave. They made the upper and lower resistors slightly lower than 1K so the pots could get just beyond the 555 switching thresholds and render a full range of control. Lastly, I would presume, the fourth opamp is wired as a straight voltage follower to buffer the loading of the capacitor from the opamp input capacitance which may change slightly with voltage (varacter diode effect... or not.). I would have designed it that way as I hate unused component sections on my boards. If I paid for it, I'm going to use it, by golly!

[@EternityForest]

I remember accidentally breaking one of those on a job once just by shorting an output. There was all kinds if stuff going wrong there and some much more expensive digital dimmers were also shorted due to water damage: They were perfectly fine! Super simple 555 designs are awesome to read about, but IRL I'll take the computerized, self protected, ultra high tech design any day, because the MCUs aren't what fails, and they're not usually what costs money either. Still an interesting design though!

[@instazx2]

it never occured to me that you could just ... not use the output pin. so many times i've tried to get full PWM signals from a 555 by the stupid diode hacks or whatever

[@RedFathom]

takes a lot of fine tuning to get it to work right.

[@mikeselectricstuff]

I did it once but can't for the life of me remember why or what it was for...!

[@multiplysixbynine]

It helps that the op amp input has high impedance so it doesn't load the timing capacitor much.

[@Peter_S_]

Always keep in mind that the 555 has _two_ output pins in addition to the "outputless" implementation here. Pin 3 is the bipolar out everyone thinks of, but pin 7 is effectively an open collector output and gives you additional design options.

[@redoverdrivetheunstoppable4637]

put two cascaded, one gives an astable very short pulse and the other monostable (one shot) stage gives pulse lenght, still limited and messy comepared to a uC but with a bit of resistor\pot chosing and maybe some LTSpice sim (there's the 555 model in it) you come up with a decent 1-100% duty with separate frequency adjust, pretty suitable for tesla coils considering the pulse length stay fixed when varying the frequency

[@Gainn]

"The 555.. An elegant timer for a more civilized age.."

[@ATMAtim]

That's pretty cool. I like simple miracle circuits.

[@RexxSchneider]

The way a 555 works is that it has an upper threshold set at 2/3 of the supply voltage and a lower threshold of 1/3 of the supply. So the sawtooth on pins 2 and 6 swings between 1/3 and 2/3 of the supply. Naturally, the potentiometers will be 1K to fit with 910R resistors to supply and ground because the comparators (op-amps) are only seeing a swing of 1/3 of the supply.

[@SCAPE0GOAT]

Great video Clive I thought the 555 was the Ducks Guts as a kid. Still have a drawer in my parts boxes full of them. Great educational vid mate. Nice 🤟👍

[@Richardincancale]

I really liked your sharpie diagram explaining the circuit. I *really* wish you’d get your scope out and show it in action!

[@stevenruhl8456]

I've seen a similar circuit to PWM RC servos. It used transistor constant current source to generate a triangle wave.

[@eDoc2020]

That makes sense. The circuit as shown here produces a nonlinear ramp. It's fine for controlling lights but if controlling servos you'd probably want it as linear as possible. Then there will always be a constant turns ratio between the knob and the servo.

[@ghostkhadaji]

neat circuit and great explanation of its operation!

[@selkywaters]

High praise for this controller.

[@uwezimmermann5427]

the capacitor in a 555-circuit is not charged to the rails, but only between 1/3 and 2/3 of the supply voltage defined by the three internal 5 kΩ resistors (in the original version of the chip, hence the name 555). Hence the 910 Ω resistors and the 1 kΩ potentiometer also give you a 1/3 to 2/3 comparison voltage.

[@GEORGE-jf2vz]

WHAT !!!!! Something electronic that does not have a microcontroller in it. Utter sacrilege. What sort of sorcery is this?

[@russellhltn1396]

While this circuit is simpler, it does beg the question of if it's cheaper. You've got 3 ICs and a bunch of resistors. It starts to add up when you consider assembly costs. With ultra cheap microcontrollers, it final product might be cheaper to go digital.

[@Peter_S_]

@@russellhltn1396 People seem to not count the cost of programming ICs. That cost offsets a whole lot of cheap components because of the logistics of dealing with parts in tape. If you're not ordering enough to be programmed by the MPU manufacturer, the cost can be fairly huge in the scheme of things. I've had a mass-manufactured microcontroller product on the market for years which has a total parts cost of about $1 (2 connectors, 3 chips, 4 caps). To have Digikey install the code prior to assembly was $0.25 PER CHIP.

[@johndododoe1411]

@@Peter_S_ Hence why you use the board testing rig to program the MCU during the go/nogo test, possibly leaving it disabled on failed boards (to discourage grey market sale).

[@TheEmbeddedHobbyist]

I programed a attiny85 to act like a 555, so I could have a uC version :-) just for the fun of it

[@Peter_S_]

@@johndododoe1411 LOL!!!!! I've built the programming and testing jigs and built several 10s of thousands of boards myself. All I can do is chuckle when reading that comment. Boards like this one are not given full QC... they get sampled QC from batches, if that. Programming is a pain and takes LOTS of assembly time. You need multiple stable connections to the board via an extra cost header or via pogo pins and pogos get flakey after a while.

[@GenaTrius]

I've wanted to build something like this for my LED+heater lava lamp project for a while. In my inexperience, I tried using potentiometers directly, with mixed results. I'll have to try my hand at building this circuit

[@bigclivedotcom]

Potentiometers are no good for high current loads. They have a very low power rating.

[@GenaTrius]

Hmmm, well I could buy some of those rheostats the size of my fist from my local surplus electronics store...

[@danielhorne6132]

The values of the pots are usually printed on the front above the shaft . Like 1k-10k-50k etc

[@SidecarBob]

I've known that Digital Command Control for model trains uses pulse width modulation for a long time but this is the first time I've heard how the pulses could be made so easily. BTW: I'd love to see you play around with some DCC stuff one day...

[@Nono-hk3is]

If anyone else was struggling to figure out why the green colored areas seemed wrong (there was less green area in FULL than in HALF or LOW), It's because the mosfets are switching ground, so it probably would have been better to fill in the area between the 5v rail down to wherever the orange line (the pot voltage) intersected with the triangle wave, rather than filling from the zero volt line up to the orange/triangle intersected line.

[@analoghardwaretops3976]

good explanation for thos who were confused with the timing waveforms..👍👍

[@BradTech.]

wow I love that circuit methodology!

[@AERVBlog]

I just love watching your videos. So succinct and informative. Is the any chance you could do a video showing how you draw your schematics? Especially your method of layout. I have a heck of a time doing that without ending up with a mess.

[@TheDefpom]

That is funny, I was thinking about one of these things yesterday for my bench background lighting.

[@stevelloyd5785]

Pot being 1k makes complete sense with 910 ohms either side, this means the wiper voltage will be @min less than 1/3 of 5v and @max greater than 2/3 of 5v. Since the timing capacitor voltage ranges from 1/3 to 2/3 Vcc this means the pot can adjust from fully off to fully on via the comparitor (opamp)

[@91rickstar]

I actually ordered one of these yesterday

[@rarbiart]

the module's housing breathes early 1980ies vibes. Add some venere decal for the ultimate touch...

[@stargazer7644]

What does that even mean? It's a box.

[@rarbiart]

@@stargazer7644 younger people may not be nostalgic spotting such a front plate and generic module boxes like isel or kemo.

[@burtgummer9057]

Bought some led tape with a dimmer a while ago. Just opened the dimmer and guess what's inside... 😉😜

[@lordjaashin]

intel inside?

[@DuroLabs85]

@@lordjaashin LOL :P

[@d.t.4523]

A fortune cookie that says "That wasn't chicken"? 😉

[@smayds]

A tiny man watching a readout dial and throwing an equally-tiny lever like a maniac?

[@chillzwinter]

A baby dimmer?

[@twocvbloke]

The 555 is certainly a rather universal little chip if people know how to fit it in, just looking at the 555 projects site has me more then confused at how they figure this stuff out, but it's impressive to think how old it its, but continues to be used to this day... :)

[@jong2359]

This is one of the more interesting projects you have broken down. Not that the other projects are bad on their own, but this is essentially like taking a clapped out Fiat engine and repurposing it to run a towns water purification plant. Although the 555 is nearly useless in this day and age, it is a rather impressive result from a single 555 timer.

[@bigclivedotcom]

The 555 keeps appearing in industrial products as a threshold switch that can drive a relay directly. It's still a very popular chip because it is a very useful set of building blocks and has a long history.

[@analoghardwaretops3976]

The 555 is > 55years+ and still running..& well-stocked in stores around the world..the internals are so simple ..with a dual comparator & 3-4 transistors ..the discrete 555 could be home built.. what's a micro to that..every 3-5 years a new version make older one obsolete & new software development is required....that's how these u.controller manufacturers make money out of you..

[@farmersteve129]

As soon as I saw the title I was thinking 555..., then I saw the text on the picture. I'm pretty sure that I recall there being an application note in one of the old big yellow TI books that made use of the triangle wave for something similar.

[@RobKenning]

I use one of those to control low wattage heater strips. I had to rewire it though. I have had it for four years and haven't had a problem.

[@Roy_Tellason]

A while back we were in a thrift store, and I saw this little box, labeled "DIMMER". They were asking a whopping 99 cents for it, and so figuring that the box was worth that much if nothing else, I bought it. Inside is something that probably resembles what you describe here a lot, I see a voltage regulator, a 555 chip, another 8-pin chip (can't find my magnifying glass at the moment), and a MOSFET. According to the markings on the cover it's rated at 12-24V .8A. No indications of who made it or anything like that though there is some sort of a part number on the board. And a "QC Passed" sticker on the bottom of the box. :-)

[@bigclivedotcom]

Sounds like a DC dimmer for LED strip.

[@jeffm2787]

One of the classic 555 uses.

[@crystalsoulslayer]

Holy shit. I think I actually kind of understand this one! I gotta tell my mom!!!

[@calvinbrowne2126]

How very retro. Nice one!

[@paulmccoy2908]

Is this video in honor of the 555’s 50th birthday? Can you imagine developing an IC that would be relevant for 50-years?

[@danbrit9848]

A teacher all is to teach with an aid...you deff arnt in the usa...I'm so glad your education centers are way better

[@ehsnils]

I think that I did see a triangular wave generator example in the 555 cookbook that I think I have somewhere in my collections unless it has gone AWOL.

[@Peter_S_]

Anybody marveling at the oscillator presented here should take a close look at the oscillators in the Oberheim OB-X, Korg MS-20, and Roland Jupiter-4 (which makes use of a 555, LOL). Analog synth love!

[@danman32]

A simple description of the op Amp circuit is it is a comparator since it has no feedback to reduce its gain.