Huh? Since When--?

It's somewhere about 40 years old. I can remember "new product" type columns that dealt with it about 1974, but can't remember if it was around before that. The Intersil 8038 function generator is older than 1974.

About 40 years is pretty long time. I remember decades ago how fast things came along, and that often meant taking over from some older device. It seemed at the time that a given IC would have a shorter lifespan than a given tube, and then later it seemed like a surprise that some ICs had actually lasted quite a long time.

Some of it is that other things have come along. But also, things have changed. Back then, it was hard to do a function generator except in analog, in more recent times there are digital ways of doing it, and digital has certain advantage.

It's also important to note that ICs were never really introduced for hobbyists. An IC had to have some potential market, and that meant in some piece of equipment that would hopefully sell enough that the IC company would sell many of those ICs. Any time a device found it's way into hobbyist circles, it was because there was some demand somewhere out there for the device in the first place.

And so forty years ago, there was some market for an analog function generator. The XR was especially good since it was cheap, so it wasn't just in "function generators" (ie a piece of test equipment that generated signals) but for various instances where some sort of signal was needed. As long as there was enough large demand for an IC, it stayed in production. But analog is fussy, and a lot of the secondary uses for a cheap function generator IC can easily be done with digital, especially when a piece of equipment already includes a CPU. Even if someone is manufacturing a function generator, they likely would start in digital.

So all those modems that used the 2206 (I think they were used in some) no longer need them, since digital is better, besides the period when the

2206 could form a modem went out with about the 300baud modems. I think the 2206 was used in some of the cheaper analog music synthesizers, but nowadays most music synthesis is done in digital. The demand is no longer there.

That said, just because an IC is no longer in productin doesn't mean it won't be available for some time. Especially not a popular IC that was around for forty years. There will be stock around, to fulfill repair requirements, and because so many were made over so many years it won't all dry up immediately. And once no one is manufacturing with them, a "reasonable supply" is likely to be more than enough for those who actually want to use the IC. Or if the IC was popular enough, cheap enough, common enough, chances are there is an endless supply sitting in all kinds of parts drawers on all kinds of workbenches, bought because it was an interesting IC or because someone needed to pad an order to fulfill a minimum order, or for some specific project that was never gotten around to.

Michael

What's not right about dropping obsolete parts?

Jameco still has some in stock. They are a good place to find EOL parts.

--
You can't have a sense of humor, if you have no sense.

Does this have the same pinout as the ICL8038? We've got several tubes of those in stock... (never to be used) (I could stick a few in the mail?)

I think digital signal generation and PIC's (etc) were the death of the old analog function generator chips.

George H.

Well, it'd be kind of like killing off the 555/7555. Think about all those thousands?-- millions?--- of circuits that use the 555 IC. While not so ubiquitous, the 2206 is an incredibly useful little IC. I don't know of any other chip where you get a sine wave past 1 MHz with so few parts let alone triangle waves. I know there other function generator chips, but if you need to pack it into a small space--- say, you were making something really funky like a sonic screwdriver--- the

2206 and its associated parts can easily be put on a very narrow piece of perfboard; ya can't do that with the 8038 or the other similar chips.

Ron

What manufacturer has declared them obsolete? The 558 is obsolete, but how many people needed four 555 timers in a single package? Obsolete means that there isn't enough demand to keep making a part. hell, you can still buy new fenders for a Ford'Model T', made with the original dies.

No one cares, if you are the only person who wants to buy them. What other function generator chips are still in production? A DDS & microprocessor is the way it's done now. The AD8950 is smaller than the XR2206, but it does take some brains to use.

I see that you snipped the link of where you can still buy them, and the link indicates they still have over 100 in stock.

--
You can't have a sense of humor, if you have no sense.

he

Not a Doctor Who fan I take it... A sonic screwdriver in fiction is a multi-purpose pocket-sized tool that does just about everything but make coffee. Most people say it can't be done in the real world but like so many things, most people are wrong.

While it's not much more than a hi-tech toy. my circuit can produce a whopping 143 dB of 13 kHz ultrasound that *will* turn screws (some of them anyway), turn keys in locks, spin dinner plates, drive your neighbor mad, and do other silly but cool tricks. while not exactly the tool of choice on many occasions, a lot of people have expressed interest in making one and the XR2206 is a very critical part to frquency modulate the main ultrasonic beam fro 1 Hz to 100 Hz.

452

Ahh, but that's why the 2206 is such a beautiful chip: it does produce nice sine waves with a minimum of support parts and the harmonic distortion can be reduced if anyone wants to take the trouble of putting in a small pot instead of a fixed resistor and checking the output on a 'scope but why bother.

Ron

. ________ "Care for a jelly baby?"

-- the 4th Doctor --

Another nice beast was the MAX038 (totally unrelated to the ICL8038) which would produce saw, square, sine, pulse, triangle waveforms up to 20 MHz. Sadly it was discontinued years ago and never replaced. Today I believe DDS is the only way to go.

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Thanks Michael, The higher frequency *would* have been useful.

George H.

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Ron have you checked out the VCO on the CD4046? (The price is right!) If you coddled it I think you can get a triangle wave output.

George H.

Doctor Who, I presume. A couple of questions:

143 dB compared to what? 143 dB SPL A-weighted? 143 dBm? ;)

At what range? A hearing aid can do that inside the ear--not so whopping at all, though it would certainly hurt.

Annoying people, that I believe. Tightening screws? Not so much.

Are you related to the other Ron Hubbard (the one with the L in front)?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

One approach is to build a sine wave oscillator, and make the triangle and square wave from that with a comparator and an op amp. The XR2206 had pretty poor THD performance due to the cheesy diode-shaping trick. You can do a lot better by using a differential BJT pair to round off the triangle, with one additional resistor to subtract off a bit of triangle to get rid of the cusp. We talked about that in sci.electronics.design a year or two back.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

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t a 143 dB at 4" to 6" which is not bad considering it comes from a handheld battery (2 sub-C cells) powered device that drives a piezo- transducer less than 1" in diameter. But like I said, just a hi-tech toy to amaze friends and sometimes annoy neighbors heh heh. ;-)

Ron

_________ "Logic is the science of being wrong with certainty."

-- The Doctor (quoting Ketterling's Law) --

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I wish I could get a sine wave from the 4046 but it has the advantage-- at least for me anyway-- is that it's VCO can be easily made to have a variable delay when frequency modulated. Makes a nice siren if someone needed it or a sound effect generator.

Ron

So run the 4046 at a higher frequency, and feed it into a ring counter that has summing resistors on the output, giving you a sinewave.

Don Lancaster wrote about it in the hobby magazines almost about the time the 8038 came out, and I think before the 2206 came out. The same area is ocered in his CMOS Cookbook (and perhaps in the TTL Cookbook, I can't remember) and in a more limited form in his TV Typewriter Cookbook.

Michael

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Phil H. has this tanh converter circuit he posted on his web site. That should make it at least as good as the exar part... A dual transistor and an opamp I think.

Then you've got a circuit that will do more than 2MHz.

George H.

is

Or let it clock a CD4020, with the 'right' resistors on the outputs... into a summing junction.

That's what I'm doing.

George H.

Annoying, people, that I believe. Tightening screws? You're making that up.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net