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sine to triangle converter
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ian-s



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PostPosted: Sat May 26, 2007 10:35 pm    Post subject: sine to triangle converter Reply with quote  Mark this post and the followings unread

Stumbled across something that might be useful.
I have been playing with the sin cos generator from the G2 building blocks. I found that you can make a good triangle wave by full wave rectifying the tops and bottoms of the sin and cos respectively, then summing the result. The triangle is at twice the frequency of the sine.
Feeding the sin and cos into a two input xor gate, a square wave is formed with a high period coinciding with the rising slope of the triangle.
This means the triangle can be converted to a sawtooth with the good old conditional inverter technique.

I thought that a hardware version of this would be quite simple, and be an ideal companion for something like the Mankato Filter. Letting it double as a regular oscillator with Triangle, Sawtooth, (PWM is easy) and a true sine suboctave.

Sorry in advance if this is common knowledge.


sine2triangle.GIF
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sine2triangle.GIF



triSawFromSinCos.pch2
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yusynth



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PostPosted: Sun May 27, 2007 12:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Well there are other ways to do so in analog electronics.
An example is to use a tri2sin converter that you insert in the feedback loop of an OPA.

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zipzap



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PostPosted: Mon May 28, 2007 12:54 am    Post subject: Reply with quote  Mark this post and the followings unread

really?

hey, this sounds interesting. sine subosc! that´s cool!

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Pehr



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PostPosted: Mon May 28, 2007 1:05 am    Post subject: Reply with quote  Mark this post and the followings unread

how about a comparator (to get a square) and then an integrating circuit to get a tri-wave? Confused

http://www.ee.duke.edu/~cec/final/node64.html

.

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zipzap



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PostPosted: Mon May 28, 2007 1:10 am    Post subject: Reply with quote  Mark this post and the followings unread

but that won´t be twice the speed of the sine. Ok, if you keep the rest you would have switchable sine or tri subosc... But than we´re propably better of building a nother vco...

anyway, that´s frequenzy dependant, right?
With higher freq the amplitude will get smaller and smaller.
but i think i´ve got something, let me have a look...

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ian-s



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PostPosted: Mon May 28, 2007 3:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Making a triangle from a sine is perhaps not so interesting. What I thought was neat was that a simple two input xor gate could be used to generate a square wave with exactly the right phase relationship to convert the triangle to a sawtooth. The sort of luxury you only get with a triangle core vco.

Seems it would only be a few dollars worth of parts to convert any quadrature sine source into a vco with a full set of waveforms.
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zipzap



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PostPosted: Mon May 28, 2007 3:30 am    Post subject: Reply with quote  Mark this post and the followings unread

I once modded a state variable filter to parform like a quadrature sine vco. It was still possible to apply input signals in vco mode (rather strong, diode limited resonance).
Wonder what your shapers would give me in that case...

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ian-s



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PostPosted: Mon May 28, 2007 3:39 am    Post subject: Reply with quote  Mark this post and the followings unread

zipzap wrote:
Wonder what your shapers would give me in that case...


That's spooky, I was just thinking the same thing.
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zipzap



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PostPosted: Mon May 28, 2007 9:15 am    Post subject: Reply with quote  Mark this post and the followings unread

alien Twisted Evil
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