Sine generator IC solution?

Are there any variable sine generator IC's? I was looking for a single chip solution, but am not sure if they exist (other than programing a PIC or similar). The frequency range I'm working with is between 200 and 2000 Hz. Ideally I'd like it to be accurate (or adjustable) to within 10 Hz.

Thanks in advance! Dave

Reply to
dave.harper
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Google for "function generator" per Mr. Shuler's suggestion. Be aware that the function generator chips generate a triangle wave internally and shape it into a sine wave. You will have some harmonics in general, and specifically they often generate a little glitch at the peak of the sine wave at no extra charge.

If that doesn't float your boat google for "DDS" or look on the Analog Devices web site for same. It's only a single-chip solution if you already have a microprocessor on board, but it may generate a sine wave that's more suited for your purposes than a function generator chip.

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Tim Wescott

Check out the Analog Devices DDS chips

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----------- Bill Sloman, Nijmegen

Reply to
bill.sloman

Exar and others make function generator chips that might work.

Reply to
Charles Schuler

What's the difference between a "sine generator IC" and a "sine generator IC solution"?

John

Reply to
John Larkin

ICL8038, MAX038 can be used to generate sine-like waveforms (made from triangle waves). That's probably the easiest way for you if you don't care too much about stability, distortion, or cost.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

It's basically an analog part:

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Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

About 500ml of solvent.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

How pure does the sinewave need to be ? This influences your options quite significantly.

Graham

Reply to
Pooh Bear

Hello Dave,

If you want a precise and stable frequency the usual function generators may not quite suffice. In that case check Analog Devices' Direct Digital Synthesis Chips (DDS). An example is the AD9833 which is inexpensive. This one needs the frequency info via SPI but they also have others.

Regards, Joerg

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Reply to
Joerg

Spehro Pefhany wrote in news: snipped-for-privacy@4ax.com:

Doesn't MAX038 generate the signals digitally,using a clock? Then freq stability depends on the clock stability.

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Jim Yanik

Whatchagonnadowithit?

IIRC a triangle has only 3% harmonic distortion. If you're using it to measure harmonic distortion, this is obviously a problem. In other applications, this might be inconsequential.

IF you're doing frequency response testing, amplitude stability over frequency may be critical.

If you're gonna differentiate it, discontinuities may be a real problem.

In the time domain, although mathematically related to harmonic distortion, the symmetry of the waveform may be of importance.

Digital soultions look great on paper, statistically, but if you're looking at the waveform in the time domain, those steps can be a real problem. Yes you can filter, but then you've got a bunch of other issues to deal with. I gave up on a DDS solution because I wasn't willing to deal with the filtering needed to get a "usable" sinewave.

If you need to gate it, there are bunches of other issues.

I'm assuming that you don't need any other waveforms, like squares and triangles. If you do, that colors your options.

You don't mention varying the amplitude. That's another bucket of worms.

The math is trivial. The implementation details can be a problem depending on whatchagonnadowithit. mike

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mike

Hello John,

A solution is usually some kind of broth that needs to be stirred at regular intervals to avoid clumping ;-)

Regards, Joerg

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Reply to
Joerg

I read in sci.electronics.design that dave.harper wrote (in ) about 'Sine generator IC solution?', on Sat, 29 Jan

2005:

Any cheap op-amp and a few passive components will do what you want. I just don't understand why people propose relatively hugely more complex solutions.

Part of engineering skill is not to spend more money than necessary. In fact one definition of an engineer is 'someone who can do for a dollar what any other fool can do for 10'.

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Reply to
John Woodgate

An op-amp (or a few discrete transistors if you ignore the "IC solution" part of the OP's question) and a handful of passives and a nonlinear element of some kind (lamp, thermistor etc.) can be used to make a Wien bridge oscillator, probably the most easily adjustable sine-wave oscillator. But the specs might push the solution somewhere else. If you google on "Wein bridge" and "Wein bridge" (the latter has 3 times as many hits, though some may lead you to bridges over the Danube) you should get some good ideas.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Provided the engineer "makes an end", rather than twiddling and twiddling and... ;-)

...Jim Thompson

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|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

That's because most of what you find on the Internet is a copy of a copy of a copy of a design. There are some good truly 'technical' web sites out there, but by and large a lot of actual circuit design and analysis is still found only in textbooks (e.g., "Sedra and Smith").

Also keep in mind that something as seemingly simple as an oscillator is a circuit that people can spend an awful long time designing in many different manners. After getting some theory from S&S, you could go and read a perhaps somewhat more practical point of view from The Art of Electronics, scurry around and find some detailed application notes on transistor or capacitor selection, etc. The folks arguing that throwing a 'complex' solution at the problem (e.g., a square wave generator followed by a switched capacitor filter) is overkill are effectively assuming that you have 'modest' needs with regards to performance; this may or may not be true.

It's getting harder and harder to give people 'simple' solutions at all anymore because technology has become so advanced. These days if someone asks here how to build a radio, they want it to use PLL synthesized digital tuning, have stero reception, etc. -- since, after, all, the $10 radio at Wal*Mart can do all that! -- and the requirements are pretty much impossible to meet within hobbyist/student constraints without turning to 'complex' solutions such as single chip radios.

---Joel Kolstad

Reply to
Joel Kolstad

In

dollar

Indeed, but you assume that I majored in that area. I'm an ME by degree and occupation, so my knowledge in that field is limited. I don't criticize you for taking your car to the shop. :-) Thanks all for the valuable insight.

Dave

Reply to
dave.harper

single

a
200

I'm trying to make a radio modem that can be controlled via a PIC. I've managed to create one that can communicate via RTTY and AMTOR-FEC (ham radio protocols) at 100 baud, but the waveform looks like the PIC threw up on the oscope. My software is still able to decode it at 100 baud without a problem, but at higher speeds it's becoming an issue. So I'm looking for something to create a less nausiating wave form and would cause less problems for the recieving software to decode at higher speeds. That's why I'm concerned with the tolerance on the frequencies... What about a 555 with tightly toleranced resistors and caps, and a double-integrated output...?

Dave

Reply to
dave.harper

One of the Analog Devices DDS chips is the ultimate sine generator. Just give it a clock and serial data, and dump the current output into a shunt R-C to ground, and you'll have a sine programmable over six or so orders of magnitude in frequency with the same precistion as the clock. The low-end parts are cheap.

John

Reply to
John Larkin

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