some vanishing point questions

[cakeworks]

Hey all.

Just got a few questions for anyone with the patience to listen to me.

http://img.photobucket.com/albums/v515/TheToneGod/vanpoint21/vanpoint21_schem.jpg)


first one: I'm not too familiar with the vanishing point concept. I mean I gather that it sequences through a variety of resistance levels determined by the potentiometer... I have a fair idea of how the circuit works I think... either that or i'm completely off (don't be refrain from telling me that I have absolutely no idea what i'm doing). I'm assuming that the two points at which it connects to an effect connect to the effect's circuit where the variable resistor normally would? Is this correct?

second question: If i was to build an expression pedal jack into any given effect effect then it would work as an extension jack for perhaps a standalone vanishing point unit (which would allow sequencing for most anything)?

but the second question is reliant on the accuracy of my assumptions outlined in the first so really i'm hoping someone can shed any amount of light on this for me.

thank you 

Ps. I'm wanting to eventually (once I understand it all a little more) put the tone god's vanishing point into his tremolo design 'the bullitt'... would that not be awesome?

[The Tone God]

I'm assuming that the two points at which it connects to an effect connect to the effect's circuit where the variable resistor normally would? Is this correct?

Correct.

second question: If i was to build an expression pedal jack into any given effect effect then it would work as an extension jack for perhaps a standalone vanishing point unit (which would allow sequencing for most anything)?

Yes you can do that but it will depending on what parameters you control in the various effects. Some might need two or three poles. Some might need different values and taper. I think the way around this is to put the opto into each effect tuned for each effect.

Ps. I'm wanting to eventually (once I understand it all a little more) put the tone god's vanishing point into his tremolo design 'the bullitt'... would that not be awesome?

That certain would be interesting. Raise a few eyebrows.

Andrew

[cakeworks]

Hmm I had a think about that one... I realised that it won't be as simple as I foolishly thought.

I had it in my head somehow that the vanishing point would switch off the depth pot when plugged in (feasable) but then I thought that if it was controlling the depth then it would sound incredibly odd because the speed of the VP (which would effectively become a tremolo itself if it were controlling the depth) would just frig up the original tremolo and be like two tremolos in sequence. Grose.

Perhaps there is a way to integrate the two circuits a little closer... I was thinking to take off the oscilator from the bullit circuit and move it to the VP circuit and have the speed controlled by the same pot as the speed of the VP so that the transition between any two given resistance levels defined by the pots in the VP so that it sounds smoother and not as choppy? Does that make any sense? More importantly am I on the right track?

btw thanks heaps Andrew, both for your designs in the initial and your constant guiding presence. You're like the stompbox-building father I never had. 

[The Tone God]

Perhaps there is a way to integrate the two circuits a little closer... I was thinking to take off the oscilator from the bullit circuit and move it to the VP circuit and have the speed controlled by the same pot as the speed of the VP so that the transition between any two given resistance levels defined by the pots in the VP so that it sounds smoother and not as choppy? Does that make any sense? More importantly am I on the right track?

I don't know if the oscillator from the Bullitt can drive the VP properly. The Bullitt oscillator was solid state version of the phase shift oscillator that most tube amps use. The "chop" in the VP is caused by the sudden shift from one stage setting to another. Maybe something can be used to slow down the the sudden shift. Use the LDR as part of a RC network that drives the tube buffer that is right now attached to the opamp oscillator. You can even put in a pot in series with the cap to control the smoothening level. Hmm...the wheels are turning.

btw thanks heaps Andrew, both for your designs in the initial and your constant guiding presence. You're like the stompbox-building father I never had. 

Aw shucks. Thanks!

Andrew

[cakeworks]

Use the LDR as part of a RC network that drives the tube buffer that is right now attached to the opamp oscillator. You can even put in a pot in series with the cap to control the smoothening level. Hmm...the wheels are turning.

Due to my relative n00bieness I'm having a bit of trouble understanding what you mean... Are you suggesting that a pot and a cap in series before the led in the led/ldr section might work?

I like how this works but i guess now it's just a tube buffer with the vp as the trem really eh... oh well lol this will be fun when I get round to building it...

Edit: Oh actally I think I follow and I was on the wrong track... anyone care to collaborate?

[theblackman]

I've been thinking of building a vanishing point too as a standalone box to control some other pedals i have (moogerfooger and a resonator). I am just a newbie too, but I would a imagine that the cap-pot series bit would be attached to the output of the vanishing point to smooth out the sequencing. This would work because the charge-discharge behaviour of the cap (the higher the capacitance value the smoother the change from step to step). Am I correct??

[remmelt]

I don't think it would be that easy, right? Say we want to switch from a low setting to a high setting, this means that the cap needs to be charged relatively full so it can buffer the change. If your setting for changing the sequence is set to fast, the cap may not hold enough charge? Of course if you feed it from somewhere else the charge will be enough, but I don't know if that would work at all. Also, won't the cap reduce "resolution" too much?

Just some ideas, I don't know if they make sense at all...

[The Tone God]

That is an issue that if the cap is too big it could be too slow to respond to the stage changes. How about a small cap in series with a pot to ground ?

Andrew

[theblackman]

Well it seems to work for analogguru... (C10)

http://analogguru.an.ohost.de/schematics/Analogguru_ZeckenWeh.gif

....picked up the link from the thread on here "Seek Wah (NO CLONE)".

I wonder if there is a way to delay the sequencing slightly without the smoothing effect, that way the sequencing could be shifted back  and forth (with a dual ganged pot) when the smoothing effect is added so that the peaks and troughs are in the same place (ie the lag from the cap will not be noticed).

[cakeworks]

hmm... well i'll be ordering parts soon so I guess i'll have a play and we'll find out.

[ljkowal]

I know very little about EE but I just read that David Gilmour had his tech build a device/unit that controlled all the phasers in the band and sequenced them together from his unit. Apparently four to six phasers are active all at once for all the artists. This sounds something like what you are talking about.  Am I close?  If so I will dig out the article and see if it gave more info on what it was.