voltage controlled sinusoidal oscillator 0 - 100 Hz

kubeek

Joined Sep 20, 2005
5,794
That seems pointless to me, I think some simple 8pin microcontroller with 10-bit DAC is the easiest solution you can have.
 

Wendy

Joined Mar 24, 2008
23,415
Not everyone likes to use microcontrollers. The learning curve for a simple project is too steep for the effort, unless you plan on doing a lot of them.

I'm one of the folks that don't.

Do microcontrollers have voltage inputs? The other thing is for an 8 bit design it takes 256 steps minimum. This would mean a 256 to 25.6Khz VCO, if it outside the microcontroller.
 

beenthere

Joined Apr 20, 2004
15,819
Sadly, this is another project that could be easily done with the ILC8038. The sine output needed cleaning up, but the frequency sweep would be no problem. The equivalent part - NTE864 - is now $51.00.
 

beenthere

Joined Apr 20, 2004
15,819
Yes - I kind of expect 555's to become hard to find any time now, too.

Re the 8038, it was as if someone decided that the audio frequencies just weren't worthwhile any longer. You can still find them in warehouse operations, but you have to submit a bid for a lot (differing quantities in each lot, as well as different spec's) with a minimum bid of $500.
 

Wendy

Joined Mar 24, 2008
23,415
I doubt 555's will fade anytime soon, too many people make them, and their still dang useful. With the introduction of CMOS types they have grown in popularity and numbers, but unlike 555s the CMOS versions have more variation, which was strange. Personally I was surprised to see the LM3909 fade from view.

If the OP gets back with us we can start pinning down some schematics.
 

Thread Starter

onlyvinod56

Joined Oct 14, 2008
369
Hello
i started this thread. Actually i need the help for an voltage controlled sinusoidal oscillator. Unfortunately the topic is completely diverted. I dont want to use any digital ICS. tHE TOPIC COVERED MICROCONTROLLERS TOO.
But still i didnt get the answer.

I started new thread "pwm generator". Not even that is also not gave any satisfactory results. Topic is completely diverted and the discussions are going on. How can i break the discussions. Atleast help me here.

My friend suggested SG3524. He too dont know the complete details. I think this 3524 is not useful here. Can it suits to my project.
 

SgtWookie

Joined Jul 17, 2007
22,230
Well, you might get there with an XR-2206.
Jameco still carries them for $3.59 when you're buying singles:
http://www.jameco.com/webapp/wcs/st...type=all&ddkey=http:StoreCatalogDrillDownView

You can sweep the frequency output by applying a voltage to pin 1. Not certain how far it can be swept. Sinewave output is available at around 1% distortion.

See the datasheet on Jameco's site (above link)
Also see TAN-005, attached.
 

Attachments

KL7AJ

Joined Nov 4, 2008
2,229
Be realistic. No oscillator can generate 0Hz.

Voltage control? What control voltage ranges? 0~5V, 0~30V?

How good(i.e. low distortion) you would want the sine waveform to be?

5%, 1% , 0.1% or 0.001% distortion?
However, it's no problem to build a function generator down in the millihertz range. Check out "Lock-in" amplifiers.

eric
 

Thread Starter

onlyvinod56

Joined Oct 14, 2008
369
Well, you might get there with an XR-2206.
Jameco still carries them for $3.59 when you're buying singles:
http://www.jameco.com/webapp/wcs/st...type=all&ddkey=http:StoreCatalogDrillDownView

You can sweep the frequency output by applying a voltage to pin 1. Not certain how far it can be swept. Sinewave output is available at around 1% distortion.

See the datasheet on Jameco's site (above link)
Also see TAN-005, attached.
Thank you. But i already hav 3524. Can i use that to produce direct PWM oscillations? I dont understand the operation of sg3524. Anyways, I'll check your link.
thankyou
 

Thread Starter

onlyvinod56

Joined Oct 14, 2008
369
It has a built-in oscillator, but it's designed for fixed-frequency operation.


Read through the applications information. Texas Instruments' datasheet for that IC has a number of helpful examples.
Ok. So, i think ihav to use xr- 2206. Is there any other IC readily available with regulated PWM for variable frequencies?

XR2206 is a function generator. To get the PWM, i need to use a triangular wave generator and two comparators.
If there is no chance to get an IC with my required features, then i will work with XR2206 and comparators etc.,
 

SgtWookie

Joined Jul 17, 2007
22,230
You might use the XR2206 as a VCO to create the reference sinewave that you'll need to drive the comparator in the SG3524.

But, this is your project; you need to understand how to use both the XR2206 and the SG3524.
 

Thread Starter

onlyvinod56

Joined Oct 14, 2008
369
Well, you might get there with an XR-2206.
Jameco still carries them for $3.59 when you're buying singles:
http://www.jameco.com/webapp/wcs/st...type=all&ddkey=http:StoreCatalogDrillDownView

You can sweep the frequency output by applying a voltage to pin 1. Not certain how far it can be swept. Sinewave output is available at around 1% distortion.

See the datasheet on Jameco's site (above link)
Also see TAN-005, attached.
Hi,
sorry for this late response.
This much time it took me to get xr 2206.
now i got the IC. I had seen the data sheet too. I didn't find any such type of model as you said that voltage at pin1 is used to control the frequency. here iam sending u a link.

Can u forward a schematic.

In my circuit, the voltage of the output of a comparator must be connected to this 2206.
please help me.
sorry for this late response as i don't have a proper internet connection.
than Q

http://www.solderingpoint.com/projects/xr2206/xr2206.php
 
Pin 1 is used for Amplitude modulation. The frequency modulation is done at one of the timing resistor inputs (pin 7 or 8). The diagram is in the xr2206 datasheet, look for "Frequency Sweep and Modulation" and Figure 7.

The frequency timing is adjusted by current through Pin 7/8, not by resistance at that pin. By adding a voltage to the input you can dynamically adjust the current passing through the input pin.
 
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