Chips that should never go obsolete

Thread Starter


Joined Apr 27, 2007
This is a problem that really makes me upset. Needed chips going obsolete with no replacement parts or equivalent parts. So I opened this topic so you can tell what chips you wouldn't wish to go obsolete or disappear.

So, here are my preferences:
DM9368 - It is the only 7-segment decoder capable of hexadecimal output and is already obsolete. It as the option of lead zero blanking, very handy in some cases. In fact, it should exist a CMOS version of it.
74LS47 - This 7-segment decoder/driver is also capable of lead zero blanking, unlike the CMOS 4511 only capable of unconditional blanking and has a very unuseful lamp test that most people won't use when driving LED displays (perhaps it is for testing gas lamps).
LM1036 - This is the only readily available audio processor made by National. For very obvious reasons, it shouldn't disappear. Unlike other audio processors, it is controlled by voltages and not by currents.
LM386 - This is a 1W audio amplifier, good for small radios. Very simple to use.


Joined Apr 19, 2007
Yes,It is so frustrating when you design something only to find that the only I.C that will do what you want is now unavalible....But then again it is just as bad with new devices, take the Analog Devices AD9833, DDS I.C. It is only available in 10 lead, mini small outline package (as are many other new devices).... Will all new devices eventualy become SMT only, and all other devices become obsolete ?.....Daniel.


Joined May 19, 2004
interesting subject. i worked about 7 years where i had to find solutions to part obsolescence. but as the technology constantly evolves, and new chip families on the white boards, these once thought necessary devices may not be needed. but i agree with you they seem irreplaceable today.

Thread Starter


Joined Apr 27, 2007
Yes,It is so frustrating when you design something only to find that the only I.C that will do what you want is now unavalible....But then again it is just as bad with new devices, take the Analog Devices AD9833, DDS I.C. It is only available in 10 lead, mini small outline package (as are many other new devices).... Will all new devices eventualy become SMT only, and all other devices become obsolete ?.....Daniel.
That is indeed a question that worries me too! I guess SMD are useful for the assembling corporations. The old DIP packages are indeed disappearing.

As far as I am concerned, it is impossible to solder properly a SMD package by hand. But I guess electronics is not for hobbyists anymore.


Joined Apr 19, 2007
SO......Then it is up to us lot to keep it all alive !!!!I do work a lot with SM devices, but it is best to build a working prototype in through components.... This means building small SMD assemblies and adaptors for the devices that are only available in SMT....Daniel.


Joined Dec 25, 2006
It is all marketing. Semiconductor companies look at who and what they want to compete against. This includes performance, package, and pricing...the 3 P's. (I stole that line from Bill Klein from TI.)

After a part is introduced the market determines the life cycle of a device. If no one wants it, then it slowly wanders into obsolescence.

Keep in mind the Marketing Engineer looks at BIG companies in terms of volume and revenue rather than Joe's Garage or a hobbiest.


Joined Jan 28, 2005
I believe RoHS compliance along with the continued momentum toward industry-wide acceptance of SMD has resulted in an acceleration of the demise of through-hole components.

Hopefully an even wider variety of SMD to through-hole adaptors will become available over time to support hobbyists as through-hole packaged components continue to become extinct.



Joined Apr 20, 2004
The SMD to through-hole approach is a tad pricey, though. It's also to see that the SMD version of a device isn't really cheaper, even though the material cost is less.

It is interesting to see the ad in at least one industry magazine that offers to re-ball devices with that nice, reliable lead/tin solder. I wonder if the ROHS drive is more well-intentioned than practical.

Oh, yes, devices. The very useful ICL8038. The CA3140 op amp with the output strobe pin. The 2N3053 and the 2N2222 in TO-18.


Joined Jul 17, 2007
MAX038. Arguably one of the best single-chip analog function generators ever produced.

But, with a zippy microcontroller and a DAC or two... ;)


Joined Jun 30, 2006
If there is enough demand they will stay. It's just cheaper to make a board with surface mounted devices. In a reasonably simple design you don't have as many or any holes to drill, all the part stuffing is done with a machine that costs 1/3 of one employee's annual salary and they use less solder. Surface mount also has cheaper machines. Wave soldering machines are expensive and have to have the solder tested at intervals which is expensive, they break down *a lot* and they must have routine and dangerous maintainence every 8hrs of use.

I know one engineer who started a surfaced mounted board stuffing service in a pole barn. It's all to EIA standards. He has a solder application machine, pick and place machine and an oven.

The companies send him the solder paste mask, boards and parts. His process is no clean so all he does is shove boards in the solder paste mask machine, then the pick and place and then into an oven. They're then sent back to the customer. He can run this in a light industrial area and has little concern about the EPA breaking down his doors.

I can solder through hole parts that look as good if not better than any machine. It takes the proper tools. I don't have the funds to buy the microscope, soldering iron and hot air rework station that's needed to do it properly yet.

The larger leaded surface mounted parts can be soldered by hand but you do have a problem with the fine lead ones. I have done both and passed class 3 inspection but it's neither easy or fast.

BGA's can be hand placed and soldered with hot air but without a good xray your chances of success are limited. One of the hand rework stations I've seen could do single BGA removal and replacement, the board had to have a human clean the BGA pads after removal and apply solder with a small solder paste mask. The machine would place the part via camera control. Once the new part is installed it gets an Xray check then gets powered on and tested.
This was 100k worth of machinery.

The engineers really disliked BGA's but the really good new parts were all going to it. If they wanted to stay competative they had to use them.


Joined Dec 27, 2005
Even with adaptors, one must solder the damn SMD onto the adaptor! :(.. Perhaps ok for a SO8, but a bummer for tiny 28 pin parts..

Some parts on my list..
555 (TS555C)
LM13700 OTA
(isp)GAL 16V8 (going going...)

Does anyone have some tips for us aging engineers with less-than-perfect eyesight and reduced ability to keep hand movements controlled to about 1mm P-P, on how to go about placing / soldering these tiny parts? - Also, how does one get a scope probe onto one of these 'pins' ?? I want to look at signals at the pin, not on some (hopefully provided) test point removed from the pin!

I know its a disadvantage - but, even when designing a product which will be manufactured with SMD, I only use components which are available both in TH and SMD.. This allows me to develop + test the prototype first, then a SMD prototype is built - and at least the product has been 'proved' in TH first..

Alas, the number of components available in both TH and SMD is rather restrictive - and its getting worse! :mad:


Joined Apr 19, 2007
Hi again...It is sad that devices become obsolete, and it is iteresting to see the range of devices that you all prefer to use.... But there is no question that a lot of these new devices are superior to the old ones.... Take the good old 741, it is a dog compared to the newer devices, it's bandwidth is restricted, it's output will only swing within about 3 volts from each rail and under some conditions, it's output can become non symetrical.... The 555 should be banned, and every device on the planet should be shot into space (Oh well, I have just lost a few friends!!!).... The old TTL 74 series was great in it's day, but those of you who still use it are not helping the global warming problem.... Also, I am suprised that they are still teaching with it in schools and college's....It is a fact of life that things change, and it is all usualy for money, but as you have all said "for the hobbyist, a lot of these devices are important"..... Daniel.