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 Forum index » DIY Hardware and Software » Developers' Corner
ne556 ne555 triangle wave?
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synthesist



Joined: Feb 17, 2011
Posts: 79
Location: austria
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PostPosted: Sat Jan 21, 2012 4:14 am    Post subject: ne556 ne555 triangle wave? Reply with quote  Mark this post and the followings unread

hey,

I am considering about building a (preferable) low component FX-Gear for processing a drummachine or some cheesy toy keyboards.
It should containe a VCA and other stuff that I wanna gate on and off.

So is there a way to get a triangle-like wave from a 555 timer? One that can be pitched without losing shape?

I know there is a trick to get some triangle waves from cmos, but is a 555 meant to do a triangular too?

PS. the wave needs to get very low for LFO but also up to audio.

thanx
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sun Jan 22, 2012 8:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

One thing you might look at is buffering the voltage that appears on the main timing cap of the 555. It's not a perfect triangle, but it might serve your purposes. Just use a LM324 or similar opamp to buffer it.

Gary
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synthesist



Joined: Feb 17, 2011
Posts: 79
Location: austria
Audio files: 2

PostPosted: Mon Jan 23, 2012 1:33 am    Post subject: Reply with quote  Mark this post and the followings unread

...so the output of the wave would be pretty weak by itself.

Would have just been too cool to be true. I mean to to get usefull non-square waves by using the ne555 by its own. Anyways this project will be one for the future since I wanna finish my modular gear first.

Thanx,
Xonrad
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Mongo1



Joined: Aug 11, 2011
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Location: Raleigh NC

PostPosted: Tue Jan 24, 2012 7:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
..so the output of the wave would be pretty weak by itself.


Well, the wave at that point is really what makes the chip work. If my memory is right, it goes between 1/3 and 2/3 of VCC.

My main concern with trying to use it without a buffer is that the load you put on it would actually modify the timing (aka the frequency). That would be a real mess.

Gary
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mrkva



Joined: Jan 25, 2012
Posts: 41
Location: poland/slovakia/netherlands

PostPosted: Wed Jan 25, 2012 7:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

Its not a perfect triangle, but I did this:

http://falstad.com/circuit/#%24+1+5.0E-6+5.023272298708815+64+7.0+50%0Aw+192+160+160+160+0%0Aw+160+224+192+224+0%0Aw+160+224+160+256+0%0Aw+160+256+192+256+0%0Ac+160+256+160+320+0+1.0000000000000001E-7+5.4694501216872835%0Ag+160+320+160+336+0%0Aw+96+96+256+96+0%0AR+96+96+48+96+0+0+40.0+10.0+0.0+0.0+0.5%0AO+384+192+448+192+0%0A165+192+128+208+128+2+0.0%0Aw+256+96+320+96+0%0Aw+320+96+320+160+0%0Ac+384+192+384+240+0+1.0E-8+1.0108301834052384%0Ag+384+240+384+256+0%0A174+320+192+384+192+0+100000.0+0.19310000000000002+Glide%0Aw+352+176+384+176+0%0A174+96+128+160+128+0+100000.0+0.9851000000000001+Freq%0Aw+160+128+160+160+0%0Aw+96+96+96+128+0%0Ar+160+160+160+224+0+22000.0%0Aw+384+176+384+192+0%0Aw+96+96+128+112+0%0Ax+82+164+129+170+0+24+freq%0Ax+350+155+407+161+0+24+glide%0Ao+4+32+0+35+10.0+3.90625E-4+0+-1%0Ao+8+32+0+42+20.0+9.765625E-5+1+-1%0A
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synthesist



Joined: Feb 17, 2011
Posts: 79
Location: austria
Audio files: 2

PostPosted: Sun Feb 26, 2012 9:14 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks mrkva for the animation. It doesnt have to be a real triangle. I search for something thats just not a suarewave.

But if use only one Transistor as a buffer for Tri output of the capacitor it could be fine, or? I mean one Tranisistor should do the job.
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