[sdiy] L(cheapo)FO

[Michael Ruberto]

>
>So why did you draw the schematic with the non-inverting inputs
>on the top ???   :^P
>

yeah I know! the model for the LM324 was drawn that way and I was too lazy 
to make a custom model for it. On the breadboard I have a 200 Ohm resistor 
between the top of R19 and pin 14 on the 324. It's only there because I ran 
out of jumpers so I didn't include it in the schematic. I doubt it has any 
real effect on the range.

>well if that is my only complaint, it looks pretty good to me !
>I wondered about the LEDs till I saw the 5V / 10V note. OK !!!
>
>Is the sawtooth 2X the frequency of the triangle ???

Saw output is the same rate as triangle.

>
>How good is the sine output (looks good, sounds good ???)
>


I cannot view the waves but the ear-oscope says yeah! triangle sounds 
perfect to me and the sine sounds like sine but kinda fuzzy like overdrive. 
I guess there must be a glitch in the waveshape but it isn't objectionable. 
After I solder this up on some perf board I'll bring it over to the computer 
and record the waves. Then I can view them in Sound Forge...
I must say the saw sounds very nice and rude, it's got balls.

M. A. Ruberto
>
>Michael Ruberto wrote:
>
> > Got in some breadboard time today. Since both of my previous synths 
>started
> > out with an LFO I felt my new one should too. My design goal was to make 
>it
> > as cheap as possible and use only the small supply of parts I had on 
>hand.
> > Unfortunately, I had to desolder many of the resistors from scrap PCBs 
>to
> > avoid running to Radio Shack.
> > Anyway, this design works pretty good and has decent range and features
> > considering the small parts count - just 1 IC and 2 transistors. The 
>outputs
> > are sine, triangle, square, and saw up or down. I get roughly 7V peak to
> > peak from the triangle and saw outputs, 6 volts peak to peak from the 
>sine
> > output and +5V from the square.
> >
> > http://frankentron.freezope.org/source/diy_blue/images/LFO1_rev1.gif
> >
> > Enjoy!
> >
> > M. A. Ruberto
>