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EEVblog: The 555 Timer is 55 years old [video]

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Re: EEVblog: The 555 Timer is 55 years old [video]

#31

Post by cbdevidal »

regularfry wrote: post #19
3form wrote: post #2

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.

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. There's a lesson in there somewhere.

Can even build a computer out of them

https://hackaday.com/2011/08/05/building-a-computer-out-of-5...

Re: EEVblog: The 555 Timer is 55 years old [video]

#32

Post by stackghost »

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!

Re: EEVblog: The 555 Timer is 55 years old [video]

#34

Post by fortran77 »

darrinm wrote: post #27

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 :(

There was a 556 on the Apple ][ disk controller (a dual 555).

See: https://mirrors.apple2.org.za/Apple%20II%20Documentation%20P...

Re: EEVblog: The 555 Timer is 55 years old [video]

#37

Post by jwr »

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.

Re: EEVblog: The 555 Timer is 55 years old [video]

#38

Post by floxy »

megous wrote: post #26
amelius wrote: post #17

What component values do you need to time exactly 55 years? Maybe it could work if you used 5 timers?

I don't think you could do it. Not with the original BJT variant anyway. :)

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 ;-)

https://www.digikey.com/en/products/detail/tecate-group/PBLH...

Re: EEVblog: The 555 Timer is 55 years old [video]

#39

Post by jacquesm »

mnw21cam wrote: post #36

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.

That says a lot more about them than it did about you.

Re: EEVblog: The 555 Timer is 55 years old [video]

#40

Post by chromacity »

mnw21cam wrote: post #35
raverbashing wrote: post #25

Makes me wonder if we could have a 555 circuit with a trigger time of 55 yrs

How many capacitors do you have that can hold their charge for 55 years?

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?
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