Small clone

[Le québécois]

I am building a Small clone on a breadboard for playing with a little (with Tonepad schematic : Thx again). If my earring while tweaking the value is correct, the small value capacitor (150pf) between pin 1 and 3 seem to control the sweeping range of the chorus.

Q1 :
Can someone confirm the following explanation ? If the signal is a perfect A (440Hz) this capacitor will determine the plus or minus sweep around 440Hz (So if the capacitor is small the sweeping is small let say 10Hz (imaginary number!) so the chorus will vibe from 430Hz to 450Hz). If we increase the capacitor size the variation get bigger (imaginary again +/-100Hz) and the overall sound is more detuned. (At least that what I ear).

The speed / rate pot will determine how fast the sweeping will go from 430Hz to 450Hz.

Q2 :
If the above is correct : what is the depth pot (or switch depending on the mod you choose) is doing? The only thing it seem to do is to remove speed from the signal but ... I am unhappy with that explanation.  And the sweeping keep on but become less noticeable?


While I'm at it: I don't see the point of Q3 transistor. Won't it always be on and if so why not simply connect the chip directly to +9v?

Charles

[Mark Hammer]

Bienvenue Charles,

Malheureusement, les mots me manquent d'expliquer les conceptes en francais.  Comme un fonctionnaire, c'est mon obligation d'offrir les services au publique dnas les deux langues officielles.   Mes excuses sincères.

The 150pf capacitor does set the delay range.  Because of how hearing and the brain works, the faster the sweep is, the more we notice changes in pitch.  This is why chorus pedals usually have some control over the sweep width (sometimes called "depth" or "intensity").  When the speed is made faster there is too much noticeable pitch change.  Reducing how wide the sweep is makes it more pleasant.  So, at a very slow speed, sweeping from 2msec to 10msec may sound nice and thick, but at a faster speed we may want it to only sweep from 2msec to 6msec or else it sounds too extreme.

The Depth control reduces how much the LFO affects the clock circuit, by attenuating the LFO output.  This reduces how much of a change in sweep there is from the default delay time.

[Le québécois]

Bonjour Mark,

I would really like french explanations but I'm use to it  . Thanks you anyway.

The 150pf capacitor does set the delay range. 

If I understand well, the delay range corresponds to the "sweep range" that I'm talking about in Q1?

When the speed is made faster there is too much noticeable pitch change.  Reducing how wide the sweep is makes it more pleasant. 

The Depth control reduces how much the LFO affects the clock circuit, by attenuating the LFO output.  This reduces how much of a change in sweep there is from the default delay time.

The depth pot is therefore only one more tweaking on the delay range. In place of it, I could (in theory) have a variable capacitor (or switch I'm aware of the switch mod) and just turn it up or down to reduce the undesired effect of high speed lfo? This way instead of attenuate the impact of high speed LFO on the sweeping I would decrease the default sweeping time of the clock generator. 
*Why we never see variable capacitor on this forum? Are they banned or something?

I know that you are probably tired of answering these questions. I have found answer about chorus mod and clock speed and MN3007 written by you in many forums on the net. These have helped me to have a small understanding of BBD chip and their obligatory body like CD4047. Unfortunately with more understanding come more questions.

Charles

[Mark Hammer]

Heureusement, j'ai un Larousse, pi un clavier bilingue disponible maintenant.  Donc, "Let her rip!"

Bonjour Mark,

I would really like french explanations but I'm use to it  . Thanks you anyway.

The 150pf capacitor does set the delay range. 

If I understand well, the delay range corresponds to the "sweep range" that I'm talking about in Q1?
Oui, les deux sont équivalents.

When the speed is made faster there is too much noticeable pitch change.  Reducing how wide the sweep is makes it more pleasant. 

The Depth control reduces how much the LFO affects the clock circuit, by attenuating the LFO output.  This reduces how much of a change in sweep there is from the default delay time.

The depth pot is therefore only one more tweaking on the delay range. In place of it, I could (in theory) have a variable capacitor (or switch I'm aware of the switch mod) and just turn it up or down to reduce the undesired effect of high speed lfo? This way instead of attenuate the impact of high speed LFO on the sweeping I would decrease the default sweeping time of the clock generator. 
*Why we never see variable capacitor on this forum? Are they banned or something?
Non. Ils sont pas interdits. L'obstacle est qu'ils sont souvent trop grandes pour le circuit.  Mais dans ce cas la, un condensateur variable ne sera pas si grand.  Évidement beaucoup plus grand qu'un condensateur céramique, mais un taille acceptable. Mais il reste le défi de comment ajuster le valeur du condensateur.  Il sera nécessaire d'utiliser un tournevis.  Moi-même, je trouve la solution la plus façile est d'employer un interrupteur "toggle" à trois positions.  D'habitude, trois gammes sont suffisants pour plusieurs fonctions.  Et je saurais; je suis fonctionnaire!  (petit blague) .

I know that you are probably tired of answering these questions. I have found answer about chorus mod and clock speed and MN3007 written by you in many forums on the net. These have helped me to have a small understanding of BBD chip and their obligatory body like CD4047. Unfortunately with more understanding come more questions.
C'est la vie, non?

Charles