EnvoTrem a work in progress

[Kipper4]

Ok guys I'd like a little help

this is the lfo I'm testing the rest of ver 19 with.



http://commonsound.org/tremulus/tremulusnewchem.jpg

1 mod i decided to go without the shape pot so did a series 470k instead.
i figuered the thats what the lfo would see anyway

i cant get the bjt variable resistor to wobble the lfo speed.

how do I hook up the Q2 bjt var res to the lfo?
any clues as to what size series resistor im going to be looking at for R11 and R.ENV1

thanks
Rich

[duck_arse]

put the shape pot back, twist it till you get the shape you like/want best, pull the pot, measure the legs, bung in resistors, forget it happened. nearest value resistors will do, don't measure too close. "470k" will send shape hard to one end.

to envelope the speed in the lune osc, you need to shift the resistance formed by "speed" + "fine" + "100". and if you are at high speed= low resistance, any method you try to go faster ....... won't work. how much lower than 100R are you going to get? perhaps, if you reduce the 100uF cap, you can increase those R's. then you could string an LDR across that string, swing it faster from slow, at least.

if youse don'ts wants the shape control, maybe you can go to the full integrator/schmitt (I know I've got that worng) configuration instead. then you can mess w/ resistances till the cows come home.

seeing as you don't have R-to-ground to sling the transistor-resistor (transient resistor? that's what they named it at the start) across, you prolly can't use it here.

as for R.ENV, it is only there to allow the pot wiper to go to a voltage of the envelopes choosing, whilst the base sits grimly at 0V6 due to the grounded E. and, R11 swings in parallel to your R14 = 12k, so you need less than 12k to halve the resistance the osc sees that leg. or - increase the value of R14, gives you more room to move w/ R11 value.

[Kipper4]

Thanks mate.
I've had some victorys. probably too many losses though to warrent further work with the lune lfo.
It must soon be time for me to wrap this up call it a project, clean up the schematic and do a layout,
Then I can also plough some hours in on the EnphoVibe.

Edit. you were spot on I hadnt realised that i already had 4k4 as R11. My booboo was I put 2x 2k2 in series without realising.
experimented and I am now using 7k5 (cause everyone has one) for R11
shut up whinging and just use the stock 6k8.......

[Kipper4]

This actually works.
It could do with some refining,but it works with a few quirks.
A bit more quirky than the pso version but I'm glad I had a go.

I missed something out a 10k resistor in parallel with the ldr

ooops

[midwayfair]

You lose nothing by making the other half of the 4558 to buffer the LFO from the depth pot. It's literally just a jumper on the chip, no extra parts needed.

[Kipper4]

Thanks Jon will do. I just tried to copy what i have on the breadboad.

Sometimes it stalls I guess i have to change R26 1k to make it not stall.
Anyone got a ball park value I could start with so it doesnt .
Thanks

[duck_arse]

that oscillator has me baffled. how does the shape pot work, or does it? the osc might be stalling (at the fast end?) because VACT_2 is being driven too low, and R25 is not stop enough. is D4 an indicator or part of an invisible vactrol?

[Kipper4]

that oscillator has me baffled. how does the shape pot work, or does it? the osc might be stalling (at the fast end?) because VACT_2 is being driven too low, and R25 is not stop enough. is D4 an indicator or part of an invisible vactrol?

the shape only work noticably at slower lfo speed. So I guess the answer is yes.
to take advantage of it though as jon says i needed to buffer it and take the lfo signal from that buffers output.
Check out the lune schematic posted earlier.

the lfo is stalling at the slow end. The brighter the led in vactrol 2b the slower the lfo.

D4 is indeed indicator only, for my viewing pleasure. I need it in my life so I can see the light at the end of the tunnel

I'll try some bigger R25s but im fairly confident it was at its optimum already.
Thanks for questioning this. I appreciate it.

[midwayfair]

that oscillator has me baffled. how does the shape pot work, or does it? the osc might be stalling (at the fast end?) because VACT_2 is being driven too low, and R25 is not stop enough. is D4 an indicator or part of an invisible vactrol?

It works just fine. I used something similar with a PSO as well. Negative-going waves in the feedback are just shunted mostly to ground (or not).

The way we're used to seeing it in the Lune is as two diodes in series separated by the pot, essentially rectifying the output of the LFO to two signals, let's call them up and down. When the pot is in the center, you get just as much up as down, and the signal might as well be AC like it is coming out of the LFO anyway. When the pot's moved, you get more up and less down, or more down and less up.

I actually think this method is pretty neat, if only because it uses a single diode instead of two. I do wonder if there might be an even simpler implementation.

[Kipper4]

Still whittling away at this back on the breadboard.
Significant changes EA type tremolo and Charge pump envelope and lots of value changes.
Vactrol=NSL32
Also please note in the demo the 3mm red indicator is reversed and going to Gnd, Not as in the drawing.
demo later

[Jdansti]

Nice work, guys!

[Kipper4]

[moid]

Sounds great You probably don't want to hear this as a suggestion but I wonder if the effect could also rise in pitch as the tremolo speeds up or lowers in pitch as it slows down? I've no idea how you'd do such a thing by the way!

[duck_arse]

sounds pretty good to me. goes faster, goes slower, sweep seems seamless. bosh?

[Kipper4]

Don't think I'll ever finish it

Bosh

[deadastronaut]

you need another 29 pages like my threads...

sounds great..

[Kipper4]

Quick question.
Any reason why I couldn't, shouldn't use a 5v regulator to bias the lfo?

Datasheet...


http://www.ti.com/lit/ds/symlink/lm78l05.pdf

[deadastronaut]

 bias is usually 4.5v ...which you have on your voltage divider...

not sure about replacing that with a 5v reg.....hmmm...

[duck_arse]

there's no reason you can't bias the lfo with VB^*, get shot of a few extra parts.


^* the voltage, not the beer.

[Kipper4]

Thanks guys.
I will bias the lfo with Vb.
I tried biasing the lfo with a 5v regulator because I thought it would eliminate some noise.
It works fine. However it doesnt save space and adds a lot of heat and doesnt eliminate noise. I tried.
The noise is coming from the extra gain at output transistor,
I'll be honest theres plenty of gain on the output. Probably not needed.
It only makes the extra noise when I'm not touching the guitar strings......

Also I have got rid of the two x LM358 and the whole thing has a much smaller footprint pcb with a new LM324 qaud chip and no added noise from the lfo or anything else on the breadboard so I might go with it.
I was weary because I expected there to be problems with using a qaud. Lfo leakage or cross talk.
Not so.
Layout on the way and I'll box it up next week.

If anyone cares to do there own layout feel free or volunteers are sought to check mine thanks.
I'll repost an upto date schematic too
Rich