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DIY Stompboxes => Building your own stompbox => Topic started by: Hal on February 03, 2004, 06:19:42 PM

Title: Ansil's Trem...
Post by: Hal on February 03, 2004, 06:19:42 PM
Has anyone tried triggering the LED with a triangle wave yet?  I'm about to try that, with the schem I got from play-hookey.com

i'll post how it comes out... (if it works)
Title: Ansil's Trem...
Post by: Hal on February 03, 2004, 08:43:13 PM
actually...i cant get it working :(.  All I get out of the op-amp is linear voltage....here's the link.
http://www.play-hookey.com/analog/triangle_waveform_generator.html
how can I mess that up?

I haven't really gotten anything with op-amps to work.  I think my problem is providing them power.  I've heard you need voltage halfing circuits or something...  True? I've just been connecting Vcc to the + on the battery and V- to ground.  I'm using a TL072.

Thanks.
Title: Re: Ansil's Trem...
Post by: Ansil on February 03, 2004, 09:01:02 PM
Quote from: HalHas anyone tried triggering the LED with a triangle wave yet?  I'm about to try that, with the schem I got from play-hookey.com

i'll post how it comes out... (if it works)
hmm i havent'. sorry,  i just packaged up two of them and sold them
Title: Ansil's Trem...
Post by: ExpAnonColin on February 03, 2004, 10:36:31 PM
Quote from: Halactually...i cant get it working :(.  All I get out of the op-amp is linear voltage....here's the link.
http://www.play-hookey.com/analog/triangle_waveform_generator.html
how can I mess that up?

I haven't really gotten anything with op-amps to work.  I think my problem is providing them power.  I've heard you need voltage halfing circuits or something...  True? I've just been connecting Vcc to the + on the battery and V- to ground.  I'm using a TL072.

Thanks.

If you're going to connect the V- from the op amp to ground, you're going to need a Vref in there at 4.5v.  Try connecting a 10k resistor from ground, a 10k from your V+, and a 10uf cap from ground all to one point and you should get a near perfect half of your voltage.  Now, that's what you use as ground in terms of the op amp.

Here's a schematic I did of a very similiar design:

(http://experimentalistsanonymous.com/images/tremolo/duallfo.gif)

That includes the vref schem.  Hope that helps!  :)

-Colin