Do we need Saw waves  ?   - Page 1
Forum section: electronics / beginners

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 18, 2011, 05:45:00 pm
content: Yes , do we need Saw waves ? :-)I would like to know , in what cases , you do use Saw waves for ?Like testing a gear ?Or use it, so to repair something ?

author: Simon
author_rank: Unknown
timestamp: May 18, 2011, 05:50:56 pm
content: err.... no saw waves = no TV's, CRT monitors or CRT scopes. Really are you truly asking such a silly question ?

author: johnmx
author_rank: Frequent Contributor
timestamp: May 18, 2011, 06:17:51 pm
content: It's widely used by PWM controllers, music synthesizers and many more.

author: Simon
author_rank: Unknown
timestamp: May 18, 2011, 06:27:48 pm
content: yep that too, although can be often interchanged with triangle waves but then a saw tooth is a triangle I suppose with 100% duty on the rising or falling edge

author: Neilm
author_rank: Super Contributor
timestamp: May 18, 2011, 07:26:20 pm
content: Look at the current waveform in a flyback PSU transformer - if you see a nice sawtooth waveform you can tell you have the frequency and duty cycles reasonably correct.Neil

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 18, 2011, 09:15:46 pm
content: Quote from: johnmx on May 18, 2011, 06:17:51 pmWell from what I have read so far , the PWM uses square waves with controllable duty cycle.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 18, 2011, 09:17:06 pm
content: Quote from: Simon on May 18, 2011, 05:50:56 pmThis is the Beginners club ... I love silly questions

author: johnmx
author_rank: Frequent Contributor
timestamp: May 18, 2011, 09:44:42 pm
content: I have 4 different PWM controllers in stock: DRV591, DRV593, MCP1630V and TL594. All of them use a sawtooth waveform (AKA ramp) to control the duty-cycle.Let me google a picture….got one (see attached). If those two signals (in black) are the input of a comparator then the PWM signal (in blue) is generated. If one input signal is higher than the other, then the output will be low, else will be high. The period of the PWM signal is the same as the sawtooth waveform.

author: RayJones
author_rank: Frequent Contributor
timestamp: May 18, 2011, 11:18:26 pm
content: Sawtooth waves are very much used all over the place.Useful for time bases, ala horizontal analogue CRO beam deflection, CRT monitors (sawtooth current actually), ranging systems, servo system error determination (ala PWM feedback).Heck even your prized Fluke DMM probably uses saw waves for the dual slope conversion system.Let's not forget they also are good for cutting wood

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 19, 2011, 12:47:18 am
content: from what i google not so long ago. sawtooth waves consist of all integer harmonics, ie 1,2,3,4 where square, albeit infinite, do not consist all integers, if i'm not mistaken, only odd integers, ie 1,3,5. so sawtooth is better at analyzing other signal's noise/thd, and mostly used in audio... well, thats what i read, i never got involved in audio.

author: allanw
author_rank: Frequent Contributor
timestamp: May 19, 2011, 06:02:40 am
content: PWM uses a sawtooth wave. Digitally, there's a counter that decides when to turn the PWM signal on or off. You can look at this as a signal as a sawtooth wave and a comparator that toggles the PWM signal.Function generators can be implemented with something that generates a sawtooth wave. A square wave is generated with a comparator (same as PWM). A sine wave is generated by filtering out the higher frequencies.It can also be useful for testing clipping distortion in amplifiers. You can visually see if the sharp corner of a triangle wave is missing.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 19, 2011, 08:20:03 am
content: Quote from: allanw on May 19, 2011, 06:02:40 amThis is a great TIP ..Thanks allanw.Quote from: RayJones on May 18, 2011, 11:18:26 pmNice TIP too ... LOL

author: RayJones
author_rank: Frequent Contributor
timestamp: May 19, 2011, 08:29:47 am
content: Quote from: Kiriakos-GR on May 19, 2011, 08:20:03 amBoom tish