555 and other "suposedly" obsolete IC's! - Page 1
Forum section: electronics / general

author: MT
author_rank: Super Contributor
timestamp: September 08, 2015, 12:24:28 am
content: 555 designed by Hans Camenzid (RIP) a brilliant design and still manufactured, how can it be? Perhaps just NOS wafer stock?Should'nt this chip be obsolete and replaced with ""any" 8bit PIC in 8DIP/SO8? If not what existing market is using the 555in such volumes that motivates elephants like TI to manufacture new 555 wafers? (555 means both bipol and cmos version)Other IC's that should have been obsoletete but is still not? 741?

author: Chris C
author_rank: Frequent Contributor
timestamp: September 08, 2015, 12:36:44 am
content: I couldn't find current data, but supposedly over abillion555's were manufactured in 2003 alone.You can't run a MCU directly off 18V. Or have it switch that voltage directly, much less at 200mA. I guess that's still a point in the 555's favor.

author: retrolefty
author_rank: Super Contributor
timestamp: September 08, 2015, 12:54:11 am
content: QuoteQuoteDon't know why there would still be a demand and in what volume to justify their continued production. However there must be enough demand for some reason. Perhaps they just make a batch now and then to replenish inventory when needed? I do see beginners often using them as they try and duplicate some old published circuit, not knowing that there are so many pin compatible op-amps with much better performance and specifications.

author: JoeN
author_rank: Frequent Contributor
timestamp: September 08, 2015, 06:26:18 am
content: There are still LS family ICs manufactured by TI and probably others. It's not obsolete until people stop using it. Otherwise the manufacturers are completely happy to sell it to you, they already sunk all the fixed costs into it decades ago.LM741 - Also still active at TI, you can even sample it, or buy one of the 17,000 of them that Digikey has in stock, or one of the 14,000 Element 14 has in stock. TI is simply not going to stop making them if someone wants to buy them.

author: krivx
author_rank: Frequent Contributor
timestamp: September 08, 2015, 08:10:03 am
content: The 741 is old enough that the amount of process control and testing required is much less than any other product TI makes. It's probably one of the cheapest wafers for them to do, I would not be surprised if they run them whenever they have the capacity.

author: poorchava
author_rank: Super Contributor
timestamp: September 08, 2015, 08:11:41 am
content: It's the same as with logic gates. Stuff like HC14, HC132, HC4051, HC4052, HC4053, HC02, HC595, 4094 any many more are still used. Of course, you could fit hundreds of them in simplest CPLD around, but ordinary gates are just cheaper and quicker to use. Unless space is a major problem, discrete gates are the way to go.405x are still the cheapest way of multiplexing analog signals if you need it.Yes, I do recall myself using a PIC10F200 instead of four 555's, but that was due to space constraints, otherwise I'd go with NE555 or something based on standard logic.

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: September 08, 2015, 08:48:35 am
content: You don't have to faff around programming a 555 like you would a MCU ... Less is more

author: plazma
author_rank: Frequent Contributor
timestamp: September 08, 2015, 09:00:49 am
content: I recently made a led video light pwm controller with a JK flip flop and ICM7555. The 555 is still very useful.

author: bktemp
author_rank: Super Contributor
timestamp: September 08, 2015, 09:13:13 am
content: You can see a 555 quite often in all kind of circuits. But I have never seen a 741 in a circuit designed in the last 30 years. LM358 seems to be the cheapest opamp available.

author: poorchava
author_rank: Super Contributor
timestamp: September 08, 2015, 09:51:16 am
content: 555 is just useful and versatile. Sometime you just don't need anything more. Same with LM358, sometimes you just don't need anything better, and LM358 is just easier to use than ua741 (IIRC the latter does not operate near any of the rails on neither nor output).

author: commie
author_rank: Frequent Contributor
timestamp: September 08, 2015, 12:27:13 pm
content: When I was at college 1987/8(final year), we were told the 741 was/is the industry standard. Given that it is still available I reckon it still is the industry standard.However, an opamp introduced by Raytheon way back in 1975, the 4558 dual opamp has a much better spec. than the 741 and costs just 0.07 pence each in quantities of 100. The reason it is so low cost now is simply because lots of designers are using it. Two good op amps which have disappeared are the LM101 and LM308, the latter device was particularly good for building chopper amps.

author: @rt
author_rank: Super Contributor
timestamp: September 08, 2015, 04:08:47 pm
content: Sometimes the best solution to test an obsolete chain of 595/169 shift registers is an obsolete 555 for the clock signal and an obsolete flip-flop for the data signal, an obsolete red 5mm LED at the last obsolete register output.Otherwise you would need five or six lines of program code.

author: Fraser
author_rank: Super Contributor
timestamp: September 08, 2015, 05:46:13 pm
content: The modern FLIR Ex series of thermal cameras have an optional external charger. It contains a smart charge manager IC but there is an SMD 555 on the PCB just to make the charging LED flash.These IC's are known as building blocks. You use them and they just work. No issues of programming or concerns over corruption of memory contents. They are resilient components that are much used, well understood and reliable.I openly admit to being a dinosaur as I am aged over 45, but I hope my experience has made me a wise dinosaurEvery design does not HAVE to have a microprocessor or micro controller in it to do a good job. If a couple of BC108 transistors will do the job well, use themAurora

author: rob77
author_rank: Super Contributor
timestamp: September 08, 2015, 06:33:18 pm
content: 555, 358, 393 - you can build a space ship with those

author: MT
author_rank: Super Contributor
timestamp: September 08, 2015, 07:45:29 pm
content: Interessting to read your wievs on this and here is related story on the theme as to why i brought up the 555!Back around 2005 Intersil declared CA3280, CA3080 and CA3083 etc, EOL, this move upsetsome people since these chips are vital for specific designs so people started to send desperateSOS messages to Intersil from Titanic and on the wire Intersil replied:QuoteThe design dates for the chips in question rolls back to 1969, 1971 so juding by the reply from thisIntersil employee these chips we could buy back in 2005-6 was from a wafer stock that wasallready 20 years old!That's why im contemplating over the 555 being made from a huge old wafer stock supplyingthe market rather then actuall new silicon fabrication.

author: Macbeth
author_rank: Super Contributor
timestamp: September 08, 2015, 09:07:34 pm
content: Surely we should be able to print our own dies for these ancient chips DIY at home by now? I mean these old fab designs are well within a good inkjet or laser printers capabilities, even if scaled up like the SharpZ80 on glass. (I've still got my old MZ-80A in the loft)Jeri Ellsworth has some great videos on making PN junctions and stuff with silicon. (Haha, why is the autosense on google search coming up with "Jeri Ellsworth married"? Come on guys!)

author: krivx
author_rank: Frequent Contributor
timestamp: September 08, 2015, 09:10:13 pm
content: I don't know if the Intersil case is the same - hasn't the 555 been second-sourced by pretty much everyone?

author: klunkerbus
author_rank: Unknown
timestamp: September 08, 2015, 09:34:44 pm
content: To be thorough, it should be noted that not all 555 parts are the same. Improved, somewhat newer 555 chips are out there. The ICM7555 and TLC555 for example are based on CMOS technology and don't exhibit some of the nuances of the original 555 like high current spikes when the output switches. I don't remember about the ICM7555, but the TLC555 even has different RC component equations due to being CMOS based.

author: MT
author_rank: Super Contributor
timestamp: September 08, 2015, 09:48:32 pm
content: Klunkerbus!Quote

author: klunkerbus
author_rank: Unknown
timestamp: September 08, 2015, 10:51:36 pm
content: Yeah, I had saw the reference to both bipolar and CMOS, but it's a safe bet there's some reading this that don't realize there's a difference. I DO consider the bipolar 555 obsolete and quit using them years ago, but use the CMOS variety any time I need a generic activity indicator or other pulse stretcher that would just be a PIA to do any other way.

author: MT
author_rank: Super Contributor
timestamp: September 08, 2015, 11:55:05 pm
content: Thats exactly why pointers is for new-old-wafer stock, also cmos variants, despite any design variation, is old, i briefly checked my cabinet of old ic's and found a couple of ICM7555's dated 86 week 13, and if i dig i'm sure i would find way older then that!

author: AF6LJ
author_rank: Unknown
timestamp: September 09, 2015, 12:15:15 am
content: Quote from: MT on September 08, 2015, 07:45:29 pmThis is interesting, I just went looking for a replacement for a CA748 for grins and giggles.It was your basic uncompensated biploar Op Amp but since it had a biploar front end you could do things with it that extended into the low UHF region. They made high frequency discriminators, V-F converters and whatnot. Where I worked back in the eighties we used one to develop back bias for a varicap used in a UHF VCO. The other end of the varicap was fed with voltage from a low frequency discriminator to keep the VCO in lock.I am sure there is something out there that can do the job..Just not a CA748.

author: westfw
author_rank: Super Contributor
timestamp: September 09, 2015, 06:22:09 am
content: QuoteThose are pretty important... Particularly if you consider that one of the easiest and least expensive way to get a modern microcontroller to do a 200mA 18V push-pull output is probably ... connect it to a 555.

author: station240
author_rank: Unknown
timestamp: September 09, 2015, 03:53:53 pm
content: One of many uses of the 555 is to provide a power on reset pulse to a micro, instead of the cheap capacitor+resistor which isn't usable for a bus involving multiple chips.Plus issues like power consumption, milspec, failure modes (less transistors = less to go wrong).Quote from: MT on September 08, 2015, 07:45:29 pmIronically I found a tube of 5 CA3080 DIP in a box of other random junk.Some of the PAL/GAL type chips are EOL, or just hard to find.

author: SeanB
author_rank: Super Contributor
timestamp: September 09, 2015, 07:31:56 pm
content: 555 has a very good use, as it is space rated, so finds a lot of use in satellites as drivers, timers and such, as it will survive a lot of abuse supply wise, temperature wise and radiation wise. Being able to directly drive a relay with reasonable power capability has it's uses.

author: AF6LJ
author_rank: Unknown
timestamp: September 09, 2015, 10:02:47 pm
content: Think about it; One of the very few parts to have a book dedicated to its use.

author: K5HJ
author_rank: Regular Contributor
timestamp: September 10, 2015, 03:52:43 pm
content: A quick Digikey query shows that 555s are available, in stock, from at least 10 different manufacturers with prices starting at 9.6 cents.Hard to beat that.Randy

author: JoeN
author_rank: Frequent Contributor
timestamp: September 10, 2015, 09:18:23 pm
content: This book is more or less all about 555 applications as well:www.amazon.com/Timer-Amp-Optoelectronic-Circuits-Projects/dp/0945053290/

author: AF6LJ
author_rank: Unknown
timestamp: September 10, 2015, 10:33:44 pm
content: Just think in Six Years the 555 will turn Fifty Years Old.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 11, 2015, 11:09:48 am
content: Don't forget the 556 dual timer and the 74xx123 multivibrator.

author: Deathwish
author_rank: Unknown
timestamp: September 11, 2015, 11:17:37 am
content: Quote from: AF6LJ on September 10, 2015, 10:33:44 pmShh, don't remind me it is younger than me

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: September 11, 2015, 11:38:46 am
content: Quote from: AF6LJ on September 10, 2015, 10:33:44 pmThe 555 will easily be around in six years time; Maybe Dave could do a limited edition batch of 50th anniversary 555 Timer T-Shirts

author: mzzj
author_rank: Super Contributor
timestamp: September 11, 2015, 11:42:21 am
content: Quote from: Chris C on September 08, 2015, 12:36:44 amplus there is no eeprom to fail or ram to corrupt or stupid programming mistake to halt your flashing led after 49 days of operation...Component sourcing is another thing, 10 years ago AT90S1200 would have been common jellybean MCU for "led flasher" and but now its obsolete.Wich MCU should I pick NOW to ensure availiability after 10 years? 555 is very likely also available after next 10 years.

author: ivan747
author_rank: Super Contributor
timestamp: September 11, 2015, 12:58:17 pm
content: Quote from: retrolefty on September 08, 2015, 12:54:11 amTHIS. Why is the 741 still used, really? Even the LM358 (or its single version) kicks its ass and isstillolder than me! OP07 as well.

author: ivan747
author_rank: Super Contributor
timestamp: September 11, 2015, 01:13:00 pm
content: I would like to see a TTL version that does not drap a current spike on output switchover. Maybe a CMOS 555 wih a TTL output stage.

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: September 11, 2015, 01:15:10 pm
content: THIS ==>https://en.wikipedia.org/wiki/Atari_Punk_Console... is why the 555 Timer is still alive and kicking. Also, I just checked my component stock, and I'm amazed to say I still have half a dozen 741's stashed away for a rainy day

author: AF6LJ
author_rank: Unknown
timestamp: September 11, 2015, 01:17:55 pm
content: Quote from: Deathwish on September 11, 2015, 11:17:37 amSame here..

author: AF6LJ
author_rank: Unknown
timestamp: September 11, 2015, 01:18:55 pm
content: Quote from: GNU_Ninja on September 11, 2015, 11:38:46 amThat has a high Coolness Factor, I would buy one.

author: MT
author_rank: Super Contributor
timestamp: September 11, 2015, 02:21:47 pm
content: I recall Hans was also behind many of those peculiar PLL chips like 556, 565, 564 etc he has several PLL patents metioning these.Download his book its great, very educational.http://electronicdesign.com/trends-amp-analysis/555-timer-was-just-beginning-hans-camenzindhttp://www.designinganalogchips.com/

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: September 16, 2015, 02:47:31 pm
content: Quote from: MT on September 11, 2015, 02:21:47 pmGreat linkthat book is gonna be my bedtime reading