Looking for simple DIY sine wave generator plans

[Gazucha]

Hi all,

 does anyone know of a simple, stable - and preferably cheap - circuit to generate sine waves up to at least 200Khz? No probs if it includes square wave option too.

 Cheers in advance...

[Stonent]

Complete with example circuits!

http://www.jaycar.com.au/images_uploaded/XR2206V1.PDF



http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&pa=34972&productId=34972&CID=octopart

They have them for about $8.00 but I've seen them for around $4.00

[Harvs]

There are DDS sinewave generator boards off ebay in the region of $5 delivered.  Maybe the easiest option if you're just trying to get to an outcome.

[Experimentonomen]

Those dds ic's usually need serial comms to make them work, and i dont think the op wants to go through that.

[nctnico]

A board is not a chip! And most boards have a display, buttons and USB.

[fcb]

Those $5 DDS boards tend to be a DIP header board, no micro/buttons/display/USB.

The OP needs to define stable or give an indication of use.  If they may be able to get away with a simple discrete Wien bridge oscillator, or need something disciplined with a PLL or something rock-solid like a DAC based DDS.

[Gazucha]

Hi again,

 Thanks for all your suggestions.

 I've seen those DDS boards but couldn't find any connection schematic and I'm also in Brazil where they are not easy to find, and as was pointed out, seem to need other components, which I am not at all sure can be found here.

 What I had had in mind, was something that could be fine tuned, so maybe with sub-sections on the tuning 1-50Khz, 50-100Khz etc.

 It would have been cool if there was a chip for sine waves, as the 555 for square waves, that just needed peripheral components. I know there is the 2206 but have never used one. That XR-2206 schematic from Stonent looks interesting but where or how could you adjust the frequency? 

 I actually have a signal generator, but was looking to build something for the fun and experience of it, to use on an experiment searching for harmonic frequencies. It should be able to hold a 6 digit frequency for at least 5 seconds. Better still have a slow sweep, which leads us back to the XR-2206 boards, eh? What do they need then? PSU, display (or reader) and ?

 Thanks again.

 

[Stonent]

That's just an example schematic but there are 3 potentiometers on it for adjusting frequency, amplitude and I think symmetry.

I've seen other projects based on that that have a fine and coarse potentiometer and a readout.

[G7PSK]

What about one of these from ebay the seller is in Hong Kong.

http://www.ebay.co.uk/itm/The-New-DDS-function-Low-frequency-test-signal-generator-module-sine-square-cis-/200950656828?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2ec997af3c

[Stonent]

https://sites.google.com/site/guenterbartsch/home/xr2206-based-function-generator

AVR Based one

[rdl]

Here is the original Exar TAN-005 (function generator app note) which may be useful.

[Jay_Diddy_B]

Hi,

How about a simple Wein Bridge Oscillator?

There are many ways of stabilizing the output voltage. Hewlett and Packard used an incandescent lamp. I have chosen some small signal diodes.



Hint: Make sure op-amp has enough gain bandwidth, GBW and slew rate, SR for the operating frequency.

Jay_Diddy_B

[Gazucha]

 As I already have a digital Function generator, and don't really fancy getting into coding, I like the look of the Wien Bridge Oscillator. I half remember these from college but that was 30 + years ago and I never stuck with an electronics career. I'm sure we made one with a filament lamp.

 What frequency range does the LT1028 cover? And is there any more info regarding connections? Seeing as the are 8 pins to consider... And is it a variable on R2 for frequency variation?

 Are there not idiot-proof instructions somewhere?

 Gonna go get the chip anyway...
 

[ivan747]

As I already have a digital Function generator, and don't really fancy getting into coding, I like the look of the Wien Bridge Oscillator. I half remember these from college but that was 30 + years ago and I never stuck with an electronics career. I'm sure we made one with a filament lamp.

 What frequency range does the LT1028 cover? And is there any more info regarding connections? Seeing as the are 8 pins to consider... And is it a variable on R2 for frequency variation?

 Are there not idiot-proof instructions somewhere?

 Gonna go get the chip anyway...

It is described in the book "Electronics Principles" by Malvino and Bates. I have the spanish version of the book (on clearance, very cheap  ). There must be a portuguese version in Brazil. It is theory, you said you didn't want an idiot-proof circuit, try to make your own with that book. Tip: make sure your op-amp can handle more than 200kHz, many common op-amps may not do it. I think the TL-072 could do it.

[Gazucha]

 Ok, just been into the Centre of Rio and none of the electronics shops have any kind of op-amp, so that puts that plan on the slow burner. I'll check online as they will for sure have something in São Paulo (350 miles away!).

 This is part of the reason I was seeking something simple.

 No worries.

 Any other ideas more than welcome....

[Jay_Diddy_B]

Gazucha,

Many op-amps will work in the Wein bridge circuit. Common ones that will work:

TL082 or TL084
CA3140
LF353

To change the frequency you need a ganged (stereo) potentiometer. Both R1 and R2 should be varied at the same time.



Jay_diddy_b

[Gazucha]

Will try again tomorrow and already have various ganged pots waiting to be used.

 Just to rewind a bit...

 As I am planning to use harmonics, it could also possibly work if the circuit only generated 30 - 40Khz.

 Would that make things any easier?

 cheers

[Gazucha]

 Hi Pippy,

  the idea was to modulate clean sine waves, thereby creating harmonic sidebands with which to reduce the electrical resistance in a particular medium.  At present these sidebands are created by combining a lower Mhz RF carrier signal with sine (or square) wave audio frequencies, which are mostly between 4 and 40Khz, although it would be great to have a comfortable and stable capacity up to and beyond 200Khz.

 This can comfortably be achieved with both my Function Generators but I had been hoping to find an easily constructed and cheap alternative. It just seemed the best place to start, by asking for a simple sine wave generator. If it is too much of a ball-ache, then we'll just stick with something along the lines of a  555 square wave circuit, however the Mhz signal MUST be sinusoidal.

 Hope that helps.
 

[fcb]

Whatever happened to people using transistors?

If you don't need to (easily) vary the frequency, then use a single transistor phase-shift oscillator.

[Gazucha]

Problem being that it is essential to easily vary the frequency as the idea is to search and find optimum harmonic variations.

[Conrad Hoffman]

I've always been a fan of the XR2206 but the ones available today don't work right. Over about 11V they won't cover their frequency range, if they oscillate at all. I still have an old one, and those work per the data sheet. Best to build something with opamps or discrete. Actually, if you want to copy something clever, with a very wide range, download the manual for a Wavetek 185 sweep generator and look at how they do the oscillator in that.

[lesaid]

I know there is the 2206 but have never used one.

I played with one of these a while back (bought three or four of them cheaply from EBay) - was easy to use and did what it said on the tin from the schematic on the data sheet.

BUT - beware - don't take liberties with the output impedance of 600 ohms. Through a silly mistake, I drove a lower impedance during a breadboard experiment and damaged the chip before I realised what I was doing. It seems very intolerant of overloads. It worked normally for maybe a minute and then started producing strange waveforms - I think I fried part of the output circuitry. Ensuring I really was driving 600 ohms and replacing the chip solved the problem.

[edavid]

Hi Pippy,

  the idea was to modulate clean sine waves, thereby creating harmonic sidebands with which to reduce the electrical resistance in a particular medium.  At present these sidebands are created by combining a lower Mhz RF carrier signal with sine (or square) wave audio frequencies, which are mostly between 4 and 40Khz, although it would be great to have a comfortable and stable capacity up to and beyond 200Khz.

 This can comfortably be achieved with both my Function Generators but I had been hoping to find an easily constructed and cheap alternative. It just seemed the best place to start, by asking for a simple sine wave generator. If it is too much of a ball-ache, then we'll just stick with something along the lines of a  555 square wave circuit, however the Mhz signal MUST be sinusoidal.

 Hope that helps.

What does this mean?  What are "harmonic sidebands"?   How could they "reduce the electrical resistance"?  Does this make sense to anyone else?

[fcb]

yes, yes, haven't you seen "Chain Reaction"...

[Gazucha]

 Hi all and apologies for the delayed response.

 As per usual, just when you think you have free time to play with your own ideas, along comes a shed-load of work to ruin your plans! We have a saying in Brazil... Rough translation is, "If you wanna make God laugh, just tell him (or her) your plans..." (guaranteed to screw them up).

 Conrad... Thanks for that input, I'll take time and check it out...

 eDavid... Harmonic sidebands are created when using an RF 'carrier' frequency (2 - 4+ Mhz) to 'deliver' a lower bandwidth (e.g. audio) wave into something normally inaccessible such as a living cell, only I was wondering about the possibility of hitting a liquid substances 'resonant' frequency in such a manner, thereby reducing the electrical resistance in said substance, thereby reducing the current needed to create the required reaction. I.e. MORE VERSATILE!

Anyways,  possibly one of the most successful developers of sideband harmonics was Philip Hoyland (Dr. Rifes engineer)

If you still need clarification, please check this link... Sidebands are halfway down but I recommend you read it all.

http://rifevideos.com/chapter_9_1938_to_1939_beam_ray_corporation_clinical_rife_machine.html


Thank you everyone for your input.. Very appreciated.