Triangle waveform out of a 555?

gmeredith · Posted: Wed Oct 18, 2006 11:23 pm Post subject: Triangle waveform out of a 555?

I've built a vibrato circuit from Mikmo's plans, and all is working well. But is there any way of getting a triangle or sine wave out of it, instead of just the standard square wave?

Cheers, Graham

Uncle Krunkus · Posted: Thu Oct 19, 2006 2:54 am Post subject:

Getting a smooth slow sine or triangle wave is actually a bit trickier than you might think. AFAIK it has something to do with integrating an RC oscillator. Have a look at how Ray made the LFO for the SoundLab on the MFOS site.

Scott Stites · Posted: Thu Oct 19, 2006 6:19 am Post subject:

I don't think it's a triangle wave - ramp IIRC? - but, if you want a different wave out of a 555, buffer/level shift the signal off of the timing cap. That's a pretty interesting wave all by itself.

Cheers,
Scott

richardc64 · Posted: Thu Oct 19, 2006 7:14 am Post subject:

It's a ramp whose slopes are of unequal steepness as the timing resistor is varied, which in itself could be interesting. It would have to be buffered by a FET or high impedence opamp. If I remember correctly, the ramp only swings between 1/3 and 2/3 the supply voltage.

Scott Stites · Posted: Thu Oct 19, 2006 9:27 am Post subject:

Yep - I used it as an extra output in my then-breadboarded but long put-off Fluctuating Random Voltage adaptation from the 266 SOU. That circuit uses two 555's (actually 556, or in my circuit, 7556), and I had a buffered, level shifted output from each timing cap. Buffered with TL07X IIRC. It's a relative freebie in any 555 based oscillator, works pretty well for Schmitt trigger oscillators also.

Cheers,
Scott

choklitlove · Posted: Thu Oct 19, 2006 5:07 pm Post subject:

this is from a book. it should be able to produce square and triangle with one 555. if not exactly what you need, it should help. if not, sorry:
Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

it's from Encyclopedia of Electronic Circuits Volume7 by Rudolf F. Graf and William Sheets. originally in Popular Electronics.

gmeredith · Posted: Thu Oct 19, 2006 5:48 pm Post subject:

Thanks guys for your advice, that helps a lot, and thanks choklitlove, the schematic seems to be just what I need!!

Cheers, Graham

iorobyy · Joined: Sep 26, 2005 Posts: 65 Location: Italy

ne566 maybe is the simplest solution... a very clean triangle wave out for default!

gmeredith · Posted: Sun Feb 04, 2007 2:54 pm Post subject:

Is the 556 directly compatible pin for pin with the 555? Also, is it CMOS (low power drain)?

Thanks, Graham

fluxmonkey · Joined: Jun 24, 2005 Posts: 708 Location: cleve

State Machine · Posted: Sun Feb 04, 2007 7:34 pm Post subject:

gmeredith · Posted: Sun Feb 04, 2007 8:00 pm Post subject:

Thanks for the links, everyone, that is lots to go with! Seems as though it's easy enough to get a triangle wave out of the 1555.

Cheers, Graham

richardc64 · Posted: Mon Feb 05, 2007 5:02 am Post subject:

I worked with a guy -- my boss, actually -- who wouldn't design with 556s because he didn't have the pinout memorized, like he did for the 555. Rolling Eyes

State Machine · Posted: Mon Feb 05, 2007 5:03 am Post subject: