Keantoken's CFP cap multiplier

[keantoken]

Okay... Getting there. Vbc(Q2) is lower than the total voltage drop which must mean there is another broken joint? What is the voltage across R1? Vbe of 1.15V for Q1 means it is probably dead... But I don't know why that would happen. Q1's pinout is CBE looking at the flat side.

The layout appears to be correct based on my guesses of where the pins are.

[naf]

hi kean,
do you mean Vce(Q2)?, i try to simulate with ltspice and Vbc(Q2) is less than Vdrop
Vce(Q2) = Vdrop

something wrong with my part,
here my real measurement
Q2
Vbe -0.62mv
Vce -2.4 v
Vbc 1.43 v

Q1
Vbe 1.15v (???)
Vce 1.46v
Vbc -0.7v

[keantoken]

Yes, I meant Vce.

Okay... Vbe-Vbc=Vce. For some reason this doesn't hold up in your measurements. In any case a Vbe of 1.15V means Q1 is fried; replace it, or test it for Hfe in case it really isn't bad, of which there is a remote chance.

If that doesn't work, add a lytic of any size to the input. Your goal is to get output AC below 1mV. With 136mV input it should be at least .27mV. Until then the circuit is still broken. If this doesn't work, then I'm flabbergasted.

[naf]

okay i'll replace the part and do meaurement.
but today i'm busy with my work.
will report back to you.

thank you.
naf

[keantoken]

Tinitus, anything interesting about the sound? Or does it just do what you expected?

[naf]

hi kean,
yes Q1 was dead, replacing a new one
here my measurement
dc in 23.36v
dc out 21.9v
ac in 0.172v
ac out 0.138v

q1
vbe 0.555
vce 1.08
vbc -0.22

q2
vbe -0.630
vce -1.79
vbc 1.09

i think this is correct dc value for q1and q2.

[keantoken]

That all looks right, except your input-output DC gives 1.4V whereas Vce(Q2) is -1.8V... And output AC is still way too high. And how did Q1 get fried!?

I'm sorry this is taking so long. How long do you wait after turning it on to measure it?

Measure again with 1k resistors in series with each probe, and the probe wires twisted. If this doesn't make the measurements consistent, then I think your meter must be flaky.

[tinitus]

Originally Posted by keantoken

Tinitus, anything interesting about the sound? Or does it just do what you expected?

on my bass ? .... best I have had yet, or actually, much better, and almost where I want it
all commercial units are now out of my system

I can explain it very simple
there is none of all the strange ressonances or artefacts that plagued me a lot before
and now I can always find a setting that sounds right
also very nice that I don't need the compressor either
may be the compressor works better now, I don't know
but I don't need it, thats certain

actually, I still need that buffer, and with +/- symmetric power supply
so the next will also have your negative k-multiplier

[iko]

Hi keantoken, I can't find a model for the 2SA1930. Can you share it please?

[iko]

Actually, found this in another thread. Is this the one you're using?

.MODEL Q2SA1930 PNP(
+ IS=10.000E-15
+ BF=210
+ VAF=78
+ IKF=10.000E-3
+ XTB=1.5
+ BR=.1001
+ VAR=100
+ IKR=10.000E-3
+ ISC=10.000E-15
+ CJE=3.252E-12
+ CJC=63.196E-12
+ MJC=.33333
+ TF=83.239E-12
+ XTF=10
+ VTF=10
+ ITF=1)