Fun fact: his original concept needed 9 pins and therefore was going be forced to have a 14 pin package. A late epiphany got it down to the 8 pin version we know today.
3form 8 hours ago [-]
5:55 video released on May 5th, as per description :)
For something feeling like a fairly specific IC, I remember seeing many projects that use it throughout the years in wacky ways - and seeing it makes me happy to know that the sentiment for this little piece is shared.
regularfry 6 hours ago [-]
The trick is that it's sold as a timer but it's really a kit of parts from which you happen to be able to build a timer.
That's fine, but you know you have to concatenate them and sell them as one unit, right?
darrinm 5 hours ago [-]
As a kid I didn’t understand what the 555 timer chip on the Apple II disk controller was doing but I learned the hard way that when you misalign the pins on the drive connector cable and the 555 chip releases its blue smoke you can’t use the drive anymore :(
JKCalhoun 3 hours ago [-]
I have read as well that the 555 was used in the game paddles for the Apple II. 555 + potentiometer (the part you turned) varied the length (duty cycle?) of a square wave which the Apple II used to determine the paddle position.
aidenn0 1 hours ago [-]
The port that was standardized on for PC joysticks was the dumbest possible one:
The joystick itself just had 1 potentiometer per axis, wired directly to the port. The port had no A/D, no timer, and no interrupt. Instead there was a GPIO and a capacitor. You discharged the capacitor with a GPIO write, and then polled the GPIO to measure when the capacitor was charged again. The number of iterations through your polling loop would be proportional to the position of the axis.
This is a pain to emulate if you aren't doing cycle-accurate emulation. IIRC Dosbox has a bunch of kludges and still doesn't get the joystick right for every game.
[edit]
To clarify the game port used a 558 (quad stripped-down version of a 555) as a schmitt trigger, so it generated pulses of a width proportional to the potentiometer position. I looked up the Apple II interface and it looks very similar, but with the caveat that accelerated versions (e.g. the IIgs) would always clock to 1MHz when reading the joystick port, compared to the PC that could run at a huge range of clocks (and CPI) over the lifetime of the port.
PunchyHamster 13 minutes ago [-]
I remember using similar trick to use LEDs to sense light. Basically, charge the (reverse biased) LED capacitance, then measure how long it takes to discharge.
The lil circuit I had was LED bar, so I used it to sense finger position using that (other leds providing light, LED doing the sensing judging that light and comparing to rest
fortran77 5 hours ago [-]
There was a 556 on the Apple ][ disk controller (a dual 555).
I still have the Forrest Mims III Radio Shack "555 Engineer's Mini-Notebook" somewhere in my basement. And rumor has it that Sammy Hagar can't drive 555 because his car just isn't fast enough!
jshprentz 7 minutes ago [-]
Also consider the IC Timer Cookbook by Walter G. Jung.
MisterTea 6 hours ago [-]
The Mims books are fantastic. As a kid I collected every mini notebook and the green Radio Shack "Getting Started in Electronics." They were my intro to electronics along with the Radio Shack kits.
stevekemp 6 hours ago [-]
I have a paper copy of "IC 555 projects" kicking around on my bookshelf still!
Very cool. (Looks like it uses 26 transistors. I assume the die is similar.)
tuvix 7 hours ago [-]
Built an atari punk console using these with my late father. Still have it hanging on my wall in a shadow box.
swed420 7 hours ago [-]
I recently dug one out to use as a hardware shutdown timer to power off an rpi's PSU once it has presumably halted without having to resort to a dedicated MCU for the task.
davidwritesbugs 7 hours ago [-]
Oh god I feel old. I remember being an excited schoolboy thinking how magic this was when it debuted.
davidwritesbugs 7 hours ago [-]
I also remember being amazed, and did a forehead slap, when an old army bomb disposal man explained how, what I thought was an innocent device, was used by the IRA in bombs.
nickcw 7 hours ago [-]
Ha. When I was a teenager I used to build 555s into timers for the same purpose using a no PCB rats nest construction.
Though surprising the family at dinner with a small explosion was a much more innocent purpose.
Brian_K_White 6 hours ago [-]
For me that is blue leds.
mhh__ 2 hours ago [-]
"rareleds" on Instagram is fantastic. Vintage LEDs set to apex twin and so on
davidwritesbugs 6 hours ago [-]
Yes! I remember thinking "damn you band gap physics, if we only had blue leds we could do colour displays with LEDs, but that can never happen."
jwr 4 hours ago [-]
The 555 timer is still the most popular chip that hobbyists add to their parts inventory (see rankings at https://partsbox.com/ecdb.html). I find this both interesting and curious — I'd say it has mostly nostalgic value at this point. Almost every practical problem today is better solved by something else. And yet it persists, I guess mostly because of beginner tutorials and first LED blinky circuits.
One nice thing about the 555 is that at least it aged well and still is very usable in those beginner tutorials. Unlike for example the uA741 which no one should use.
mnw21cam 5 hours ago [-]
I used one of these to win an inter-school science competition when I was ~13. It was a minute timer. The competition board doubted I had built it all myself, so they plonked it down in front of me and demanded I draw the circuit diagram in front of them.
jacquesm 4 hours ago [-]
That says a lot more about them than it did about you.
sho_hn 5 hours ago [-]
I have a Displate of a decapped 555 hanging near my EE workbench:
Back when radio shack still existed I would buy a 555 timer during every visit. I live collecting them and still have a bunch somewhere stored. I continue to do it with the 328p arduino boards as well whenever I visit my local microcenter.
nqzero 2 hours ago [-]
!remindme 500 years
OldSchool 5 hours ago [-]
As an electronics-enthusiast kid in the 70's, just before home computers showed up at all, I wished the 555 was for Time Travel
encom 6 hours ago [-]
Can't watch it right now, but upvoted for Dave Jones. He's taught me so much. Absolute treasure, and the host of one of the last great active forums. Thank you for not blackholing all that info on the disaster that is Discord, like so many other communities.
stackghost 5 hours ago [-]
When I was a camp counselor in my 20s I designed a one-octave "piano" out of one of these, a battery, paperclips for keys, and a shitload of resistors. We had the kids build them on proto board. They sounded harsh but you could play Mary Had a Little Lamb on them!
amelius 6 hours ago [-]
What component values do you need to time exactly 55 years?
Maybe it could work if you used 5 timers?
ua709 5 hours ago [-]
How exactly is exactly? Can I make it measure 1 hour with an allowed tolerance of 55 years, plus or minus. :)
megous 6 hours ago [-]
I don't think you could do it. Not with the original BJT variant anyway. :)
floxy 4 hours ago [-]
Hmm, why not? For the astable configuration, you could use a 100F capacitor with R1 = 10 Meg and R2 = 7.5 Meg, for a 55 year period. Base current for the Threshold NPN will come from the Trigger PNP (and hopefully temperature drift matches OK). Other than maybe the 100F capacitor might have some variation in capacitance and leakage current over the course of 55 years ;-)
Just another 500 years to go. I missed the beginning, probably will miss that last milestone as well.
kazinator 7 hours ago [-]
Time to slow it down to lower frequencies and give it more frequent checkups.
aj7 6 hours ago [-]
The late Harold DuBose use to use the 555 as a power inverter as it could sink 200ma at the laser companies he worked for. Convenient and cheap.
ilvez 7 hours ago [-]
killer oneshot, laughed hard..
Etoro2024 5 hours ago [-]
I used to get exited about this. Hahaha I think I miss those days.
raverbashing 6 hours ago [-]
Makes me wonder if we could have a 555 circuit with a trigger time of 55 yrs
mnw21cam 5 hours ago [-]
How many capacitors do you have that can hold their charge for 55 years?
chromacity 3 hours ago [-]
Every EEPROM is basically that, and they're designed for data retention of around 100 years. I imagine it wouldn't be hard - embed two metal plates in glass?
PunchyHamster 12 minutes ago [-]
You don't check the eeprom value by flowing current thru the cell as you do with cap
Fun fact: his original concept needed 9 pins and therefore was going be forced to have a 14 pin package. A late epiphany got it down to the 8 pin version we know today.
For something feeling like a fairly specific IC, I remember seeing many projects that use it throughout the years in wacky ways - and seeing it makes me happy to know that the sentiment for this little piece is shared.
There's a lesson in there somewhere.
https://hackaday.com/2011/08/05/building-a-computer-out-of-5...
The joystick itself just had 1 potentiometer per axis, wired directly to the port. The port had no A/D, no timer, and no interrupt. Instead there was a GPIO and a capacitor. You discharged the capacitor with a GPIO write, and then polled the GPIO to measure when the capacitor was charged again. The number of iterations through your polling loop would be proportional to the position of the axis.
This is a pain to emulate if you aren't doing cycle-accurate emulation. IIRC Dosbox has a bunch of kludges and still doesn't get the joystick right for every game.
[edit]
To clarify the game port used a 558 (quad stripped-down version of a 555) as a schmitt trigger, so it generated pulses of a width proportional to the potentiometer position. I looked up the Apple II interface and it looks very similar, but with the caveat that accelerated versions (e.g. the IIgs) would always clock to 1MHz when reading the joystick port, compared to the PC that could run at a huge range of clocks (and CPI) over the lifetime of the port.
See: https://mirrors.apple2.org.za/Apple%20II%20Documentation%20P...
PDF version here https://worldradiohistory.com/UK/Bernards-And-Babani/Babani/...
https://shop.evilmadscientist.com/productsmenu/tinykitlist/6...
Very cool. (Looks like it uses 26 transistors. I assume the die is similar.)
Though surprising the family at dinner with a small explosion was a much more innocent purpose.
One nice thing about the 555 is that at least it aged well and still is very usable in those beginner tutorials. Unlike for example the uA741 which no one should use.
https://displate.com/displate/2002057
Maybe it could work if you used 5 timers?
https://www.digikey.com/en/products/detail/tecate-group/PBLH...