5V Dual LED Blink 555

It’s possible the real circuit has more limitations that wouldn’t be represented in a simulation accurately. Just in case you may want to let the circuit run for a while and check if anything gets warm as that could suggest it’s dissipating a lot of power (assuming you’re fine with the possibility some parts like the IC or LED may break). It’s pretty common for pins from some IC to have current output limitations and dissipate heat internally if it attempts to source more than its limit. For the case of LEDs it’s always a safe bet to add series resistors to limit current for them some.

You need to increase voltage source to between 5 and 15v. and use current limiting resistors for your leds.

the 555 timer needs 5 to 15v

I would use 9v and 470R for the first led and 330R for the second led. Good luck have fun.

Oh and don’t forget to use a 10nf capacitor connection between ctrl and ground.

Thanks to you all for the assistance! Snowfats: I've left the physical one I made similar to the videos running overnight and it seemed fine. I thought it was odd that there were no resistors inline with the LEDs since every other odd thing I have made with LEDs seemed to require resistors... unless the intent was to create a device that destroyed LEDs. Beaker651: The video called for a single Li-ion cell, so that's how I powered it... Essentially, if you look at 7:23 of this video you can see the air wired example of the version I replicated: https://www.youtube.com/watch?v=38kVFDdDC8A. At the 7:39 mark he posts a schematic. I also thought it was odd that the video called for only 3.7V nominal for the 555, since I thought it required 4.5 to 15V. None of the bajillion of videos I watched seemed to ever bother connecting anything to pin 5. It's just so odd for me to hold in my hand this thing that's blinking, and then attempt to simulate it and see that there should be a failure. My take away is that I really don't know what I am doing, I don't know how to properly use the simulator, the simulator falls short of mirroring actual performance, or I should buy additional insurance for my house because I now have more than a few "potentially overly excitable" objects in it that I have mad scienced together.

There are a few different manufacturers of 555s, they generally drop about 2 volts from power in to device output, sometimes simulators are a bit off with their voltage drops, but rule of thumb is, always use a current limiting resistor in led circuits, and don't run the leds too bright.

BillyT: So while the version in the video might actually work, and the one I made might actually work, this is likely only due to the unique characteristics of the components used. In theory, what they presented, and what I replicated is not "good".

That's about right.

Here are a couple of reference 555 circuits _ _ http://everycircuit.com/circuit/5997908791656448 and http://everycircuit.com/circuit/5212107531091968

So, assuming that I can actually power the 555 from the voltage of a single 18650, it seems that all I had to modify from the original video was to add a 100Ω resistor in front of LED1, and a 25Ω resistor in front of LED2. This keeps both LEDs at 20mA with the nominal voltage of the 18650. Well darn it all... LED2 blows if the Li-Ion cell is at full capacity. Closer, but still not what I was hoping for.

4.2V is normally the 18650's charging voltage, not its full capacity, if you were going to use a voltage that varies that mutch, it would pay to Zener stabilise the power supply to the 555. Also in reality there are normally 3 currents shown for a led, and while 20mA is normally shown it does not have to be the one used.

Well... I've been meaning to learn what the heck I would use zener diodes for. Looks like now is a perfect opportunity. Up to this point, the only real circuits I have built in the real world with diodes have just been using them as "one way valves". It sure would have helped to learn about this stuff when my brain was more malleable, but I'm figuring it out.

Perhaps my terminology is wrong with regards to the 18650 cells. I've done lots of projects with them, and I always assume that Li-Ion cells will have a nominal voltage of 3.7V, a maximum voltage of 4.2V, and a cutoff or minimum voltage of 3.0V. I realize that most cells can actually go down to 2.8 or so, but I don't like to even consider using them below 3V. I have been trying to learn about how to stabilize or standardize voltages, but still haven't gotten a good grasp on it. Whenever I use Li-Ion cells in a project, I tend to stack them in series until their cutoff voltage is over what is needed for the project, and then run that power though a buck to keep it at a predictable level. Honestly, I know there are easier ways of addressing this (as I see in almost every device I tear apart), but the theory just hasn't fully coalesced in my head yet.

There are lots of good books available to guide you on the ins and outs of batteries, there is also a bit of miss information floating around. A 555 circuit really requires 5V or more to operate reliably, and because it is only low power, it would be quite happy to run of a Zener with a dropping resistor if you were to use 2 batteries. Now zener circuits, there are quite a few already in EC.

Yeah, I've bought a ton of books, and amassed quite a collection of tools and components... sadly, after all of that I then am forced to "adult" most of the day and only have like 30 minutes of brainpower left after a day of Adulting. End result is I kinda just have to focus on whatever thing seems the most compelling. I have been playing with 18650s mostly, and have quite a few. I have four 4S4P packs that I made to power a variety of odd gizmos. Why 4S? Because it is over the voltage I need in almost every project I have made, so I can just buck the voltage to where I need instead of actually learning how to modify the voltage and\or current myself.

I should be able to use these packs to power a Raspberry Pi, an Arduino, or some similar thing but unless I use a premade buck, I only have theoretical ways of changing the voltage and getting the current I need. I wish there was a self-help group in my area for people like me, but honestly even if there were, I wouldn't want to go because there would be other people there, and I don't care for other people.

Well, changing it to 5V and not planning for the voltage to change did in fact make it easier to tune the resistors so the LEDs lighting up the same. Now either I take a 2S pack and buck it down to 5V, or I finally bother to figure out how to do it myself.