Picture of Build Your Own 555 Timer
The 555 timer. A chip so versatile that it has been used in everything from toys to spacecraft. A chip that can act as an oscillator, a schmitt trigger, PWM driver, a siren/alarm, a light or dark detector, and much much more. It is the most popular IC of all time having been around since 1971 and now selling over 1 billion annually.

This instructable will show you how to build your own 555 timer using only transistors and resistors, no ICs!

Why build this?
Good question.  There are a few different reasons:
1. To Learn:
Learning may be a scary thought to some people, but this project has taught me a lot about comparators and analog circuits as well as a lot of the basics of the 555 timer. The 555 timer combines both digital and analog circuitry  and while digital circuitry is taking over, analog is still important.
2. To Understand:
The 555 timer is a very versatile and useful chip. That's why it is the number 1 most produced chip. It is used very often so it is important to understand how the thing works. Now, you can read about it or even see a simulation, but nothing it quite as good as actually making it yourself.
3. It's Fun:
If you like working with electronics, especially breadboarded electronics, this should be a fun little project. You will break the black plastic barrier that stands between you and your integrated circuits and see the circuit in all its glory (well almost, making your own transistor could be difficult)!

Now that I've hopefully convinced you somewhere within that intro, lets get started!
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leog529 days ago
Awesome, have a question, the output drivers can put the Vcc on the output???
I See a resistor divider in the base of output drivers so i think the output should be 4.7k(Vcc-0.7V)/5.7k.
SaeedH11 month ago

what i understand is that you made 555 timer ic circuit using transistor that cool, but not everybody can make this i means its not that simple. techmess(.)page(.)tl

that's nice

gemgroup4 months ago

this is very complected & very expensive

Why so complicated ? You can make one without all those transistors, or did i miss something ?

This is an awesome tutorial! It took me a few days, but I was finally successful, after I realized a wiring mistake I made. I only did the breadboard version, I don't think I need to solder up the permanent version. I learned a lot, thanks!

ArtTech867 months ago

That is cool. Thanks for taking the time to make this awesome instructable. I will try this and things like this in the near future. Favorited and followed.

Logan Rolfy11 months ago

I've bought 2 of these online and I'm trying to make a blinky for fun. Here's the problem: it wont blink. But it lights up.

try changing your capacitor size to arouns 22-100 uf

Pure Carbon made it!10 months ago

I made it and I did an instructable on it giving an explanation on exactly where to put all the components on a perf board. You can check it out here: http://www.instructables.com/id/Remix-build-your-...

Thank you for the inspiration, and I hope that I can get you vote for the remix contest as well as the others. This project is awesome and it worked perfectly, once again thank you.

Electrospark10 months ago

Wow! This is of the best instructable i ever seen!

I can't wait to make one! :)

You just earn a Follower!

lmallari1 year ago

Hi!! May I know where are those arrows connected to? I'm trying to simulate the circuit that you made because the other 1 is more complex than yours! Thanks! Cheers

Teslaling (author)  lmallari1 year ago
The arrows represent the connection to the positive supply rail.
Lee731 year ago

That is awesome. Certainly the best how-to I've seen on here....

Red Smoke1 year ago
i was wondering what the capacitor on the pcb version was for, stabilising power supply?
Teslaling (author)  Red Smoke1 year ago
Yes, exactly.The 555 is notorious for being very noisy, especially when the output changes. I threw the capacitor on it because there was room for it and so I didn't forget during testing. I must not have mentioned it anywhere in the instructable.
thanks for the help :)
sbálint1 year ago
Hi! great work. I'm kind of new to electronics and started to experiment with building oscillators with the 555. my question is would an oscillator (for a synth) sound better with a discrete 555? Thank you!
Teslaling (author)  sbálint1 year ago
It would make no real difference. The discrete 555 and an IC function the exact same way so it wouldn't matter. You would be better off using an IC because they are cheaper, easier to use, and don't take an hour of soldering to be ready to use.
should make an atari punk console all on one board without any ICs
ondrikczech3 years ago
Nice work,try make Core2Duo Procesor :-) !
Teslaling (author)  ondrikczech3 years ago
Hahaha!!! That would be nearly impossible!!!
it'd make a very interesting project, it'd only take up half a room, though if you do it right you could overclock it to massive degrees.
Nah, do and Xeon or an i7. Get some speed goin :)
How about an ATmega128p (Arduino)
yes!!!!! do the atmega then make an arduino board around it
bloc972 years ago
Wow great tutorial!
This can show how IC's are all actually simple electronic circuits compressed together.
robot7972 years ago
no do this with tubes :P
Teslaling (author)  robot7972 years ago
Challenge Accepted!
i look forward to the result and i am even willing to supply triode tubes
Teslaling (author)  robot7972 years ago
The first thing I have to do is figure out how some of the elements can be implemented using tubes and how they would connect together. Actually building some circuits wouldn't be for a while but if you would be interested in supplying some triodes, I only have a few on hand and I know that I will need more. This should be a very cool project. I haven't worked with VTs other than with a guitar pedal.
well send me a pm and we will arange is so that the rest to happen
spikec2 years ago
Nice job, you are not only very clever but a great teacher. Thanks!
Thank you very much dude, i really appreciate it. You helped me to finish a school work and i also understood how a ne555 works.
astroboy9073 years ago
Looking at your board vs. the chip... ICs are the only reason our computers aren't still the size of a barn....
Teslaling (author)  astroboy9073 years ago
Exactly! What is really amazing is that the 555 IC only has about 25 transistors in it. A 8 pin PIC or AVR has several hundred thousand to a few million in the same exact package!
I'm sure due to manufacturing constraints there is an upper physical limit to just how many components can be put on a die in a particular package but in practice there is very little relationship between the two characteristics. Something the examples you cited point out clearly. What is amazing about the 555, that you failed to mention, is that such a simple device has been so popular for so long.

What is more amazing is that many of the tasks the more complex micro-controllers are put to today could easily be accomplished using things as simple as the 555 is.
It does get smaller every year pretty much... We are fitting some 3 Billion transistors into a processor now (thats just average), but with Haswell and intel going down to 5nm production (hopefully by 2015!), we will see massive speed increases...
5nm by 2015 is pretty optimistic. There are physical limitations they've run up against at 22nm. Being as less than 22nm is shorter than the wavelength of light they use with masks to process dies. There are interference games they can play to get a little under that but I don't think the technique can be extended very far. I've heard of some 18nm stuff perhaps that is as low as they can go? The way the industry has been going lately I wouldn't hold my breath for any massive speed increases either. First off no one needs it, second there is no competition on the high end anymore to drive it.

The way forward seems to be parallelization, multicores and clustering. Maybe teaching kids how to program again.
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