sine wave oscillator chip?

[chunks717]

It seems to me that somewhere there must exist a chip that spits out a sine wave, with frequency adjustable with resistance between 2 pins, or cap to ground range, and few or no other connections, aside from power..........

this has proven to be an impossibly difficult search, as all the terms I have tried to search with are common electronic speak.

I do of course realise a dual op-amp, and a few more externals will do this,
for the price of op-amps, I probably shouldn't even ask for more, but still

has anyone used something like this?

[Gilles C]

I used the XR2206 for mine even if I only use the Sine output.

It makes a nice sinewave, but I had to pad the signal down

http://www.canakit.net/Contents/Items/CK307.asp

http://www.solderingpoint.com/projects/xr2206/xr2206.php

This specs shhet has more infos for the hobbyist.

http://www.klm-tech.com/technicothica/images/2206spec.zip

Gilles

[gez]

IIR the current consumption of these chips tends to be a tad on the high side.  Might be something to consider if you're using batteries.

[chunks717]

thanks, looks great.......
pad signal down=attenuate?

other options? maybe less options/ lower draw?

didn't think about the chip being called a function generator....
I guess that was what I was essentially asking for

[Gilles C]

Tat's right, it takes a bit more power. The kit I mentioned (and mine) is powered with a transformer.

There are more options for an oscillator, but I was thinking "the best and simplest"

Gilles

[The Tone God]

I wouldn't say its the best but it is one the more simple options. The 8038 is in the same league. You do need to buffer the outputs and read the datasheet as there are many factors to take into account as there are limitations.

Andrew

[Gilles C]

How about "the best simple one..." 

Ah... maybe not... anyway, I find easier to get the same signal level even when changing the frequency with this kind of circuit than with circuits with only a transistor or two. That's what I meant...

Btw, I had the 8038 in mind first, before I decided on the XR2206, and I noticed many notes telling to use a more recent IC instead of the 8038. More stable, etc...


That was another reason of my choice.

Gilles

[chunks717]

8038CCPD = perfect......

limitations may make themselves apparent, but thats the ticket.

8038CCPD lists for $3.00,
ICL8038 lists for $15.90

the only spec sheet I find is the ICL version, but I am stoked to play with it......

thank you very kindly sir..................

[The Tone God]

Btw, I had the 8038 in mind first, before I decided on the XR2206, and I noticed many notes telling to use a more recent IC instead of the 8038. More stable, etc...

I've only used XR8038s awhile back so I can't say if they are better or worse then the other versions. I used the XR2206s with similar results for what I was doing with them.

8038CCPD lists for $3.00,
ICL8038 lists for $15.90

There is also a MAX version which costs more. The MAX versions can run at 5v while the others need around 12v from what I remember.

Andrew

[brett]

Try a 4049 or 4069 hex inverter, like this:
2 inverters make square waves (clip with diodes), another integrates to a sine wave (variable freq if needed), then amplify a bit and clip with diodes again.  Use a volume pot vary the amplitude of the output. 

This gives about 3% distortion, 97% sine wave, costs $1 for 9V battery, $1 for 4049UBE chip, $2 for box and $2 for pots and other parts.  Using LEDs and two inverters in parallel for output, you get up to 3.5V p-p and about 50mA.

If you're interested, I'll dig around and find a schematic and layout for it.
cheers

[Paul Perry (Frostwave)]

The Maxim MAX038 sine oscillator is no more!
So much for the company that boasted it would NEVER let one of its chips be discontinued 
personally, when I need a sine, I make a triangle & then turn it into a sine by overdriving an OTA by it (but, you will need a regulated supply to get precision of any kind). Remarkably (or not!) the cheapest one-chip solution would be a dedicated PIC or similar micro with PWM output.

[RedHouse]

XR2206 at JameCo Electronics for $3.55, BG Micro has 'em for $3.95

When I compared the 2206 with the 8038 I noticed the 8038 ran much warmer to the touch, enough that I was concerned about it being boxed up inside a small box.

I run the 2206 with an OpAmp buffer as a Function Generator

[Mark Hammer]

Take a look at this article: http://hammer.ampage.org/files/hypertriangleclock.gif

The goal of the article is an LFO that is sinusoidal for one half cycle and triangular for the other, however it details a method that can be pretty easily adapted to any old 2-opamp LFO.  No fancy chips to get, just a JFET and some diodes.

[Gilles C]

As for effects, each one has his favorite...

Btw, I forgot toexplain what I meant by pad-down.

Indeed, I found the signal a bit too high, so I added a fixed attenuator (2 resistors) for a 1 volt peak to peak output signal, because that is normally what I use to check gain of effects, or to take measures.


Gilles

[The Tone God]

The Maxim MAX038 sine oscillator is no more!

I did not know that. It looks like the wafer production was outsourced and the supplier can no longer provided them. Oh well I didn't like the price anyways and I don't use 8038s for anything these days.

When I compared the 2206 with the 8038 I noticed the 8038 ran much warmer to the touch, enough that I was concerned about it being boxed up inside a small box.

Really. I had the opposite thing happen with the XR versions of each IC but when I buffered both neither had an issue and I ran them up to 15v.

Andrew

[Gilles C]

It's not a chip based design, but I just remembered it, and thought it could satisfy many needs for someone wanting to test guitar effects.

http://www.redcircuits.com/Page92.htm

Gilles

[Paul Perry (Frostwave)]

Maybe a twin-T oscillator with a twin pot controlling the frequency? Might be able to make it a no-chip oscillator (just a transistor!)

[jmiersy]

hey ppl....very new to this and just wondering why a sine wave is wanted?


cheers
Jonathan