Sonsivri
 
*
Welcome, Guest. Please login or register.
Did you miss your activation email?
December 07, 2016, 03:20:17 15:20


Login with username, password and session length


Pages: [1]
Print
Author Topic: Sine Wave Generator  (Read 2300 times)
0 Members and 1 Guest are viewing this topic.
promach
Junior Member
**
Offline Offline

Posts: 43

Thank You
-Given: 14
-Receive: 0


« on: May 26, 2014, 05:47:46 17:47 »

Hi Everyone, I have a question regarding sine wave generator.

Theoretical Result:


Measured Result:


Simulation Result:


Besides, please find attached the schematics, netlist and model files used in

May I know why all three (theoretical, measured and simulation) results are different ?

no need to write sine_wave_generator
« Last Edit: October 05, 2014, 09:56:44 09:56 by metal » Logged
hate
Hero Member
*****
Offline Offline

Posts: 556

Thank You
-Given: 156
-Receive: 354


« Reply #1 on: May 26, 2014, 06:26:27 18:26 »

You might be saturating the transistors with unmatched or high tolerance components. As far as I can see the output frequency is also fluctuating which is another problem. Usually these kind of low-count circuits are not much reliable. Do you have an expected signal output graph submitted by the original designer (if it's not you)?
« Last Edit: October 05, 2014, 09:58:43 09:58 by metal » Logged

Regards...
optikon
V.I.P
Hero Member
*****
Offline Offline

Posts: 604

Thank You
-Given: 460
-Receive: 1603


« Reply #2 on: May 26, 2014, 09:01:09 21:01 »

In your simulation graph,

Notice the discrete levels
Notice the straight interpolated lines
Notice the units are still in uV when you expect > 1V

It looks like your circuit sim did not actually start oscillating and you are stuck in a numerical oscillation which is an artifact of the simulator.

Try setting the max time step to something small and try some initial conditions on internal nodes to get it started.
Try reducing VNTOL or supply ramping your battery to help get it started.

BTW, this junk circuit is very far from what I would consider a sine-wave oscillator but looks like you are trying to learn.
« Last Edit: October 05, 2014, 09:58:32 09:58 by metal » Logged

I can explain this to you. I can't comprehend it for you.
Sideshow Bob
Senior Member
****
Offline Offline

Posts: 457

Thank You
-Given: 160
-Receive: 495



« Reply #3 on: May 26, 2014, 10:42:14 22:42 »

Simulating ocillators can often be problematic. To make it short simulators are to perfect so oscillation will not start. And the result will often not refelect the result then building a real circuit. As the real circuit may oscillate off the calculated frequency both ways. For us others to give some help. Can you say something about the goals with your oscillator setup
« Last Edit: October 05, 2014, 09:58:18 09:58 by metal » Logged

I really am ruggedly handsome, aren't I?
TucoRamirez
Senior Member
****
Offline Offline

Posts: 277

Thank You
-Given: 197
-Receive: 95


Tuco ... dead or Alive


« Reply #4 on: May 27, 2014, 04:45:02 04:45 »

usually in spice, to simulate an oscillator you need to generate a step signal on the power supply, this forces the simulator to do his job ^^... (at least in orcad pspice and cadence spectre it happens all the time , otherwise it can't simulate not even a simple ring oscillator)  use a pwl generator for your supply, give it a 5ns on 0V and after that go to your supply nominal voltage..  regards
« Last Edit: October 05, 2014, 09:58:06 09:58 by metal » Logged

Whoever double crosses me and leaves me alive... he understands nothing about Tuco.
Signal
Active Member
***
Offline Offline

Posts: 102

Thank You
-Given: 47
-Receive: 33


« Reply #5 on: June 25, 2014, 11:26:27 23:26 »

As was already mentioned above it is not a serious sine generator. But this does not mean that it can not work at all. Moreover limitations of this circuitry are good for studying how transistor works, what is needed for self-oscillation and where is the "sine" Wink.

A good simulator helps a lot in such study. My choice is LTspice (http://www.linear.com/designtools/software/#LTspice) - you can rely on it in most hard cases. (Current circuitry is far from difficult side).

Here is the working example. Playing with values of resistors (R3,R8,R4,R5,R6) you can understand why this circuitry can not be considered as good and reproducible.

Edit: re-uploaded asc file that was corrupt.
« Last Edit: October 05, 2014, 04:53:33 16:53 by Signal » Logged

Give a right name to a right game and play it right
sarah90
Active Member
***
Offline Offline

Posts: 109

Thank You
-Given: 6
-Receive: 11



« Reply #6 on: June 27, 2014, 09:39:07 09:39 »

I have always used a dds like the ad9850 for sine wave generation. The disadvantage of these dds circuits is that you get a lot of high frequency noise that has to be filtered out. A circuit like this is pure and would not have that high frequency noise. But as said it is a bit flaky. Does anybody know a quality pure analog sine wave generator circuit?
« Last Edit: October 05, 2014, 09:59:00 09:59 by metal » Logged
Signal
Active Member
***
Offline Offline

Posts: 102

Thank You
-Given: 47
-Receive: 33


« Reply #7 on: June 27, 2014, 05:56:24 17:56 »

Quote
Does anybody know a quality pure analog sine wave generator circuit?
I like classics...
HP200A (http://www.hp.com/hpinfo/abouthp/histnfacts/museum/earlyinstruments/0002/other/0002patent.pdf)
 and its predecessor http://www3.alcatel-lucent.com/bstj/vol17-1938/articles/bstj17-4-574.pdf
Main feature of both is a usage of incandescent bulb as a power detector, low pass filter and gain control element.

HP200A was the first oscillator that allowed tuning in wide frequency range and had stable frequency at the same time. Tunable predecessors was made of two high frequency LC oscillators (one of them tunable) with heterodyne mixer and LPF to separate lower frequency component. Small frequency drifts of HF LC oscillators after shifting to lower frequency became significant and annoying. Presented rock-solid alternative was the reason why HP was so successful at start-up.

Modern view:
 
« Last Edit: October 05, 2014, 09:57:38 09:57 by metal » Logged

Give a right name to a right game and play it right
promach
Junior Member
**
Offline Offline

Posts: 43

Thank You
-Given: 14
-Receive: 0


« Reply #8 on: October 05, 2014, 09:30:49 09:30 »

As was already mentioned above it is not a serious sine generator. But this does not mean that it can not work at all. Moreover limitations of this circuitry are good for studying how transistor works, what is needed for self-oscillation and where is the "sine" Wink.

A good simulator helps a lot in such study. My choice is LTspice (http://www.linear.com/designtools/software/#LTspice) - you can rely on it in most hard cases. (Current circuitry is far from difficult side).

Here is the working example. Playing with values of resistors (R3,R8,R4,R5,R6) you can understand why this circuitry can not be considered as good and reproducible.

I have actually used an OTL amplifier at the oscillator output if you have not noticed about it.

Dear Signal, can you reupload the working ASC simulation file because it seems corrupted and cannot be opened correctly ?

Many Thanks and Best Regards,
promach
« Last Edit: October 05, 2014, 05:03:01 17:03 by promach » Logged
bobcat1
Active Member
***
Offline Offline

Posts: 151

Thank You
-Given: 1126
-Receive: 29


« Reply #9 on: October 05, 2014, 10:35:10 10:35 »

@TucoRamirez

What is pwl generator in spice ?

Thanks

Bobi
Logged
Sideshow Bob
Senior Member
****
Offline Offline

Posts: 457

Thank You
-Given: 160
-Receive: 495



« Reply #10 on: October 05, 2014, 10:56:50 10:56 »

@TucoRamirez

What is pwl generator in spice ?

Thanks

Bobi
http://www.linear.com/solutions/1814
Logged

I really am ruggedly handsome, aren't I?
promach
Junior Member
**
Offline Offline

Posts: 43

Thank You
-Given: 14
-Receive: 0


« Reply #11 on: October 06, 2014, 06:11:58 18:11 »

Dear Signal,

Thanks for your ASC simulation file.

I am actually connecting the sine wave generator circuit output to an OTL amplifier input because the voltage level is too low.
It is only 1.2V after being amplified many times by an OTL amplifier circuit.

This means the sine wave generator circuit is outputing at mV level which is contradictory to the LTSpice simulation result. I have also tried changing the impedance of potentiometer W1 and W2 but the voltage level is still too low.

Do you have any further insights on this ?

Many Thanks and Best Regards,
promach
Logged
Signal
Active Member
***
Offline Offline

Posts: 102

Thank You
-Given: 47
-Receive: 33


« Reply #12 on: October 06, 2014, 10:04:04 22:04 »

It is only 1.2V after being amplified many times by an OTL amplifier circuit.
<...>
Do you have any further insights on this ?

I do not want to install application (and do not know which one) to see your *.sch file, so I am not sure what do you call by "OTL amplifier" - but it does not matter. (Absence of explicit mention from the beginning about additional stage does matter). The captured wave (according to your first post) has a shape and frequency (40 kHz) far from expected. No need to use additional amplifier to amplify unknown interference "many times".

There are no insights besides basic knowledge about bipolar transistor (Collector Feedback Bias) and Wien-bridge. Obviously there is an error. Check your assembly. Cut off following amplification stages (your "OTL"). Check operating points of transistors. Check and/or replace transistors. Check passive components. After getting adequate biases start to change feedback coefficient (W1) to reach oscillation or to lower distortions - anyway frequency must be near expected value.

Logged

Give a right name to a right game and play it right
vern
Junior Member
**
Offline Offline

Posts: 62

Thank You
-Given: 7
-Receive: 10


« Reply #13 on: October 07, 2014, 09:30:05 09:30 »

I think there is a mistake in the schematic.
It states C1 and C2 153, but 153 what? pf, nf,?

If should be 15.3 nF for C1 and C2 each for a frequency of 473.0709 Hz
Logged
metal
Global Moderator
Hero Member
*****
Offline Offline

Posts: 2018

Thank You
-Given: 514
-Receive: 477


Top Topic Starter


« Reply #14 on: October 07, 2014, 09:49:52 09:49 »

153 = 15pF x 1,000 = 15,000pF = 15nF
Logged

nothing to say..
pickit2
Moderator
Hero Member
*****
Offline Offline

Posts: 3816

Thank You
-Given: 567
-Receive: 2049


There is no evidence that I muted SoNsIvRi


« Reply #15 on: October 07, 2014, 10:43:33 10:43 »

I just read this post and my main problem is when people use acronyms.
for a 2 transistor sine wave schematic, you need to use an OTL amplifier...
in my minds eye I see a rack of high voltage tubes, with an associated power supply.

That said, the original schematic and the one built, has why too many problem areas.
what are the true values of components, are you using, and what values your putting into the simulator.
are the components matched.
and is the built device the same as the schematic, or is there errors.

I'm from a MOD sic. (Minertry of Defence) electronic background.
Life In the workshop. Rule 1.
you don't test what you have built, that's a job for another person.
and before a piece of kit sees power most have been on 3 or 4 work bench's.
 
Logged

Note: If you have no posts other than, I want or reporting a dead link Then you can't complain If I remove your post So Stop Leeching
vern
Junior Member
**
Offline Offline

Posts: 62

Thank You
-Given: 7
-Receive: 10


« Reply #16 on: October 07, 2014, 10:54:49 10:54 »

you are right. But since everything else in the schematic is like uF and kohm, I didn't think of it.
Logged
Sideshow Bob
Senior Member
****
Offline Offline

Posts: 457

Thank You
-Given: 160
-Receive: 495



« Reply #17 on: October 07, 2014, 11:46:37 11:46 »

I'm from a MOD sic. (Minertry of Defence) electronic background.
Life In the workshop. Rule 1.
you don't test what you have built, that's a job for another person.
and before a piece of kit sees power most have been on 3 or 4 work bench's.
Perhaps kind of hard to achieve for the common hobbyist I guess. But it is something in this that a hobbyist can pick up. And that is NEVER EVER ASSUME anything, check and recheck with datasheet, schematic and theory then thing is not working. Errors often come as a consequence, assuming a component has the correct value, the component pinout/footprint is correct no need to check, and so on
Logged

I really am ruggedly handsome, aren't I?
PICker
Junior Member
**
Offline Offline

Posts: 75

Thank You
-Given: 28
-Receive: 35


« Reply #18 on: November 29, 2014, 08:28:33 08:28 »

Try this simple MCU-based approach:
http://www.romanblack.com/onesec/Sine1kHz.htm
Cheers,
PA.
Logged
Pages: [1]
Print
Jump to:  


DISCLAIMER
WE DONT HOST ANY ILLEGAL FILES ON THE SERVER
USE CONTACT US TO REPORT ILLEGAL FILES
ADMINISTRATORS CANNOT BE HELD RESPONSIBLE FOR USERS POSTS AND LINKS

... Copyright 2003-2999 Sonsivri.to ...
Powered by SMF 1.1.18 | SMF © 2006-2009, Simple Machines LLC | HarzeM Dilber MC