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That solder paste stencil looks like a neat alternative to a solder syringe when doing multiple boards. I'll have to try that.
Lets start with cfa-x #post 701 .🙂
I must leave now i'm one step before fire test "calor gold".A class A amplifier by Dr Borivoje Jagodic
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First you have to have a list of equivalents for the SMD and TTH devices. I saw one once on the forum, but I can not remember where it was posted, "I think"...
MJE340/350's do not really affect OPS performance when used as predrivers.
THD is slightly higher and the CFA IPS's slew a bit slower when these are used
as VAS devices.
I have both the 340/350's and the 1381/3503's on hand. Gain wise, both (340/350's)are
100+ current gain. 1381's are higher (e =200+) , and most of the 3503D's are <140.
We aren't getting a match anyhow - NO 3503 - e's 🙁(mouser does not stock them).
Dang , for a symmetric VAS ... like the CFA's - spooky , I might use the 340/350.
At least they match (gain wise).
Symasui and wolverine are designed to compensate for the 1381e/3503d "mismatch" .
(wolverine and symasui are both "upside down" 😀 - positive CCS/level shifter).
OS
.
THD is slightly higher and the CFA IPS's slew a bit slower when these are used
as VAS devices.
I have both the 340/350's and the 1381/3503's on hand. Gain wise, both (340/350's)are
100+ current gain. 1381's are higher (e =200+) , and most of the 3503D's are <140.
We aren't getting a match anyhow - NO 3503 - e's 🙁(mouser does not stock them).
Dang , for a symmetric VAS ... like the CFA's - spooky , I might use the 340/350.
At least they match (gain wise).
Symasui and wolverine are designed to compensate for the 1381e/3503d "mismatch" .
(wolverine and symasui are both "upside down" 😀 - positive CCS/level shifter).
OS
.
The regular suppliers seem to have ksa1381E and ksc3503D. Is it OK to mix the ranks in the wolverine circuit?
OS types faster then me...
OS types faster then me...
What I meant with the wolverine/symasui -
Since they are "un-symmetric " to begin with , the mismatch really does not
matter. If you wanted to be anal , you could adjust the gain of the active side
(the 3503's Re) to compensate for the gender differences.
The CFA's "like" a better match. (In simulation) , my "Kypton-C" CFA's servo
has to provide more feedback with a mismatched VAS pair.
Lazy cats SMD CFA uses very closely matched devices - he don't need no servo.
Through hole has it's limitations... (especially with a {non-servo'ed}CFA).🙁
OS
A good start , but by SMD ... I mean ALL SMD.
- ALL the semi's can be SMD , even the higher Ic VAS one's.
-all diodes -SMD. -all resistors -smd , even the big Zener shunt ones.
- Large caps , trimmers, euro-terminals would be the only through hole devices.
....shrink it down to 76mm X 35-40mm (3 X 1-1/2") 😀
OS
Hi OS it is useful if you can post a complete list for all IPS where needed matched trans.in VAS.
We need an SMD designer soon
Just think about it !! "Needed" might be a overstatement. "Preferred" would be
appropriate.
The servo is quite the little helper 😀 . For example , the "spook" - VFA , just a
few tenth's of a milliamp DC feedback will correct a unbalanced VAS.
CFA-X will need a few turns on one of the trimmers to do the same.
They all still work in these conditions , but they work better without.
OS