sup-simp lfo mods? A.K.A. I'll show ya mine ifa ya show me..

[guitarhacknoise]

hello,
I've been tweekin out on the super simple lfo,
The image
http://experimentalistsanonymous.com/diy/Schematics/Simple%20Dual%20LFO.gif
I was needing more in the speed range so here are some things i've found,
1. between pins 2 and 7, there is the 47k resister and a 100k pot/variable resister, I've switched that VR to 2M. and dropped the 1uf cap between pins one and two to .068 uf.
now it goes  W A Y S L O W to  ultra-FAST!
2. if you put a 33-47uf electro from output to ground you'll get a pretty nice sawtooth, smaller =faster as larger = slower...........

Does anyone have any more cool additions to this lil' circuit?
-matthias

[ExpAnonColin]

I almost always wire it up with the 100k pot as 1meg and the 47k as 10k or so.  It helps to have it be logarithmic taper like that.  I also often use a 4.7uf cap instead.

That's strange that the sawtooth is created like that...  There is a way to do this to a similar circuit with diodes:


-Colin

[guitarhacknoise]

yeah, I've seen the diodes switched in and out for different waves, but did'nt have any luck trying to adapt it to mine.
For mine the 4.7uf would be way way way slow, pop.....................................................pop...................................................pop...................
and on the passive ring mod it just makes it a really slow tremolo, with the .068uf and the 2meg log pot, It goes slow enough to be a usable tremolo and on up to get way wacky, although the higer or faster the more the carrier makes its way through.
the saw tooth cap was a lucky mistake, I was trying out different places to run the 100uf across the rails and happened to stick the + end in the wrong hole!

[ExpAnonColin]

If you're using this as an audio range oscillator.. I'd be careful, it's not super amplitude stable over a wide range of frequencies.  Look up some VCOs on the net...

-Colin

[guitarhacknoise]

suggestion/warning heeded and dually noted!
all tho vco's I've found are beyond my etching abilities, and I have bad luck on perf lately.
so far i really hav'nt had too many objections to the instability of the amplitude.
but I have been thinking of building this guy here:
http://www.midwest-analog.com/vco1.html
I guess i'll need to score the tempco first.
but for now I'm having a good time with what I got.
-matthias

[gez]

If you're using this as an audio range oscillator.. I'd be careful, it's not super amplitude stable over a wide range of frequencies

:?:  

With the stock (perhaps you've done something else to it) version of the two amp triangle generator, the Schmidtt trigger has very definite thresholds for triggering so amplitude is stable...

[guitarhacknoise]

I really hav'nt noticed the waves height/amplitude vary, but the width/speed does seem to move around very slightly when compared to a metronome for giggles.
also, I'm not trying to get this thing to the moon, so perfection is moot.
-matthias

[puretube]

totally have to agree with gez !!! (and we know what we`re talking bout).

[guitarhacknoise]

gentlemen,
could someone please explain where and why my nomenclature is off.
I do realize that the saw I speak of is not really a sawwave but it was the closest I knew of for what I see on the scope. half sine half triangle lookin deal.
also, maybe I'm just a paranoid freak, but I really hope this does'nt continue south.
Forgive me if I am reading this wrong.
-matthias
just for the record, I respect all three of ya!

[ExpAnonColin]

I must be then, because the triangle wave has never been amplitude stable.  I think it's probably because the value of the "close, but less than 100k" is too far off when I build it.

-Colin

[puretube]

Colin/gez: could it be, that in this circuit:
http://experimentalistsanonymous.com/diy/Schematics/Simple%20Dual%20LFO.gif,
the tri/square mix-pot`s value (1k) is too low, and therefore the square output loads the other output more, or less, depending of the trigger`s state? (and thus shifting properties?).
you could check out, if increasing the pot to 5k or 10k improves that behaviour...

G.H.N.: the voltage over the cap at the output for sawtoothing is (linearly) frequency dependant.

btw.: have no fear for downsouthing

[guitarhacknoise]

               
Thank You Sir!
now all I have to do is figure out what you mean, as far as..................
wait, I might have it............
tomorrow ...........
btw, I am running a 10k in place of the 1k.
-matthias

[gez]

Colin/gez: could it be, that in this circuit:
http://experimentalistsanonymous.com/diy/Schematics/Simple%20Dual%20LFO.gif,
the tri/square mix-pot`s value (1k) is too low, and therefore the square output loads the other output more, or less, depending of the trigger`s state? (and thus shifting properties?).
you could check out, if increasing the pot to 5k or 10k improves that behaviour...

Active mixers, got to love them!  

Is 'going south' a euphemism for starting an argument?  If so, then nah...we like Colin, just need to rap him on the knuckles now and again!  :twisted: ( )

[puretube]

btw, I am running a 10k in place of the 1k.
-matthias

so, that might indeed be an explanation, why You are not complaining amplitude variation,
while Colin does.

Gez: yes, from my interpretation the "south" stands for what you mentioned.
(sometimes however, I love to use geographic expressions for giving direction in large schematics... :lol: ).

Me thinks passive mixing is OK in this case, but with larger impedances...

BTW: got something nice cooking right now, concerning sawteeth...

[gez]

BTW: got something nice cooking right now, concerning sawteeth...

Smells good, what are the ingredients?!  

Phaser of some sort?  I have one on the board at the moment, though it's more of a synth sounding thing as the phase shifting is done using CMOS timers.

[puretube]

D; R; C; ...

[ExpAnonColin]

I don't have one of those breadboarded right now... just a relaxation oscillator.  I will see if that's the problem when I wire another one up.  I remember Brian Marshall was complaining about the same thing a while back...

-Colin

[guitarhacknoise]

so..................
any other modifications to this circuit out there?
Ideas are good as well.
ah...............
-matthias
yeah, south, as in:  To Hell
(same difference)

[ExpAnonColin]

so..................
any other modifications to this circuit out there?
Ideas are good as well.
ah...............
-matthias
yeah, south, as in:  To Hell
(same difference)

Well, the frequency pot could be substituted for an LED/LDR combo driven by a second LFO...

I'm going to re-breadboard it now and see if I can prevent getting my knuckles rapped in the future

-Colin

[guitarhacknoise]

wow! that's a sweet Idea!:
"Well, the frequency pot could be substituted for an LED/LDR combo driven by a second LFO... " -colin
so in other words the additional osc. would vary the pitch of the existing osc. as it ramps up and down?
too cool!
no room in this box for this right now but it's just the first one a lot of problems with it but it does work.
I got a huge lmb enc. for the "ultra version"