Hardly a week goes by that we don’t post a project where at least one commenter will lament that the hacker could have just used a 555. [Peter Monta] clearly gets that point of view. For a 555 design contest, he created both digital logic gates and an op amp, all using 555 chips. We can’t quite imagine the post apocalyptic world where the only surviving electronic components are 555 chips, but if that day were to come, [Peter] is your guy.
Using the internal structure of the 555, [Peter] formed a basic logic gate, an inverter, latches, and more. He also composed things like counters and seven-segment decoders. He had a very simple 4-bit CPU design in Verilog that he was going to attempt until he realized it would map into almost 400 chips (half of that if you’d use a dual 555, but still). If you built this successfully, we would probably post it, by the way. You can see a video of the digital logic counter, below.
The op amp, however, is a bit trickier. Each input (+ and -) have their own 555 chip. Another 555 generates a ramp, so essentially the input voltage converts to a time-based PWM signal. Some logic gates made using the 555 techniques and a pair of diodes generate pulses proportional to the difference between the signal. Finally, a capacitor integrates the output back to a voltage. If you lost count, that’s ten 555 chips to make a single op amp!
To test things out, [Peter] wired the circuit up as an inverting 10X amplifier. It worked but suffered from a few issues like noise in the output due to PWM artifacts and difficulty responding to square waves. Still, considering this is done with 555s, you have to cut some slack.
Practical? No, of course not. But it is interesting to see someone think out of the box and then try to imagine what you could do to bend a device to your will, just for the practice.
Commenters will no doubt enjoy pointing out that the logic could be done with an Arduino and there are plenty of op amp devices you can buy for next to nothing, many of which have multiple devices per package. But that really isn’t the point.
The last time we confused commenters, we saw a mix of 555 and an Arduino on the same circuit. As long as you are being impractical, you might as well go big. We thought about replicating the op amp using these giant discrete 555 “chips”.
Sheesh, so much commenter hate.
These projects are always a neat exercise in proving that things really do map out from concept to actual working model.
http://hackaday.com/2014/11/22/a-4-bit-computer-from-discrete-transistors/
400 chips? That’s NOTHING in the world of “I can make a computer out of these” projects.
But it’s got me thinking now: with the post-apocalyptic world in mind, a few articles here have showed how to make logic gates out of ferrite toroids. So now I’m wondering if powdered iron toroids would work, and if these could be made from JB Weld, or just iron filings and epoxy… Now THAT would be a pointless CPU project.
https://xkcd.com/505/
Not Mad Max enough, you need to make a set of 7400 chips out of soft iron nails wrapped with salvaged speaker wire and pounded into two by four’s and cupric oxide Diy diodes.
http://hackaday.com/2013/11/20/making-logic-with-inductors/
http://hackaday.com/2010/03/05/diy-diodes/
Echo_Hotel: well, yeah, if I was making a movie.
That diode is pretty sweet. Next step: point-contact transistors done that way.
Would that be how a chopper amp works?
Am I the only one who read the title as “You Know What You Can Do With That 555”?
Nope. Read the same thing. Lol. Good thing you said something.
Doesn’t the 555 itself contain op amps? Using it to build them seems… weird, like using a CPU as a transistor or building an oscillator using quartz wristwatches.
Yes, let’s make a 555 out for the newly create opamp just like recursive russian dolls!
Okay that would od actually be really cool
It contains comparators that are wired permanently to a latch. You can’t use their output directly.
might do to stack up on 556 chips, if you are going to be using a bunch of them on one board.
He could have done that with a 55… Wait a minute! :-)
https://www.youtube.com/watch?v=KLgY7GhvMn4
It’d be nice if the music from the radio wasn’t competing with the music in the clip.
why not just use a couple of not gates in series? (i’m totally kidding)
Why NOT?
B^)
Reminds me of this article in EDN
http://www.edn.com/design/other/4355331/EDN-Access–05-11-95-old-dog-555-learns-six-new-trick
What if I want to generate a 100khz carrier, it would waste so many cycles.
yeah. we have bitcoin miners for that…
It realy doesn’t matter if he is waisting recources. The knowledge he gets from this builds, he will never forget, true is.
Sadly it looks like the 555 timer contest website is gone
http://hackaday.com/2011/01/25/555-design-contest-win-1500-in-prizes/
Wayback Machine mirror:
http://wayback.archive.org/web/20121021113317/http://www.555contest.com/
Do you know you can do that with transistors ?
Nah, he could have done that with with an Arduino.
NOW you’re talking. An Arduino can not only emulate any logic primitive, but by use of the analog inputs and PWM outputs, can emulate op-amps as well.
Quick! Somebody get 400 arduinos, set them up to emulate 555s, and build that 4-bit CPU they mentioned out of them.
Where is timer head when you need him?
Nice, but do you know you can do that with discrete components ?
Huh, neat. I do have a huge tube of 555s lying around that I was wondering what to do with.
“We can’t quite imagine the post apocalyptic world where the only surviving electronic components are 555 chips”
What if there is a nuclear conflagration in asia sparking to the middle-east and the only fab left is a small one in the west for coarse precision 555’s?
Would be interesting to see the new iphone made from 555’s.
The NE555 must be the most
abuseduniversal IC ever…