Mark Hammer Idea

[EBK]

Going back to what I said about too many parts, I think this may be better (ignore the values):
. It's similar to Tom's original design.

Benefit of this arrangement is that your control voltage goes into the non-inverting op amp input, giving you that high impedance buffering.
I'll sketch it up and give you the relevant math once my kids are in bed. 

[Kipper4]

power supply 9v1
envelope output 2v4 no signal
envelope output with strong strum upto 7v

with a 2n5087 pnp
R3=10k (ref last posted diagram )
same output as above
let me go look at your previous calcs and see if i can figure it out
Still willing to bet its gonna be too much though.

[Kipper4]

(9-0.7-2.4)/10 000   = roughly 6/10 000  0.0006  might be too small

with R3= 2k2
6/2200 =0.0027 its still gonna make the lm13700 fry.

with R3= 4k7
6/4700 = 0.0012ma seems much more ballpark right?

[ElectricDruid]

(9-0.7-2.4)/10 000   = roughly 6/10 000  0.0006  might be too small

with R3= 2k2
6/2200 =0.0027 its still gonna make the lm13700 fry.

with R3= 4k7
6/4700 = 0.0012ma seems much more ballpark right?

Yes, it does to me.

Let's just say I'd start well on the safe side and work back, rather than the other way around.

T.

[EBK]

The negative side of your electrolytics are connected to ground, and so, there may exist the possibility of the positive side going lower than 2.4V due to leakage, etc. As a quick and dirty fix, you can bump up the negative side of the caps to 2.4V.

[Kipper4]

I just tried the analogue op amp version crossfader with a normal channel (chorus)
and an enveloped fading channel (Distortion)

It's all gone a bit 80's hair metal.
fun though.

[Kipper4]

I'll come back to the OTA version later I think.
Phaser untested in breadboard trials.
Meantime.....

HammerTime. Can't touch this.........

[ElectricDruid]

Crikey! He's firing off ideas like a catherine wheel! The chap's on fire!

T.

[duck_arse]

I have some hammer time observational questions - are you missing a blocking cap before the threshold pot, connected to Vr and the Q13, or is it in the wrong position on the dia (C77)?
and - is Q1 biasing high enough from the Q5 emitter, which would be around 3V?


don't burn the kippers, catherine.

[Kipper4]

Well That's how I have the blocking cap on the breadboard and so far I havent had any audable problems.
The reason I put it there is because of the different biasing on the envelope follower. Maybe i need another between the input buffer and the sens pot too.
Would you think it will cause an imbalance/instability?

I havent tested the phaser portion with Q1 and Q5 in circuit so I dont know the answer to the biasing question mate.

Still burning.

[duck_arse]

ahh, I see. if'n youse takes the pot to ground instead of Vr, it should be okey dokey.

[Kipper4]

Diagram fixed I missed off a cap between sens pot and buffer.
good Spot D.A.