BARACUDA-Legend-1

[6666]

Thanks its good to know these things

[porkluvr]

You would also want to have 270k matched. By the way, notice that the two 470nF are 1% units according to the schematic.

If Silverdog's resistors are 1% tolerance you should be in pretty good shape.

[6666]

Interesting about the resisters, are you only talking about R22/23 1K
silverdog kit has metal film, so should be reasonably close match ?

[porkluvr]

If you don't match the resistors in the differential amplifier... then it would probably be a waste of time to go to the trouble of matching the FETs.

When you purchase ten resistors of x (+/- 5%) value, chances are that most of them will fall within 2% of each other, but there is always the chance that one or two will be at the extremes of their rated value. Lesson of the story: match the resistors.

I read somewhere that Mr. Anchor (not his real name) would spend time with each detector. I wonder how much of that time was spent sorting out component...?

[6666]

Hi Ap
thanks , I have an opportunity to buy a bulk lot of fets
so it will be the 2n5485 fets, when they arrive
I will try and find a matched pair and attack the Bara
with the soldering iron

cheers

[ApBerg]

Hi AP
with all your testing with matched 2N5485 and Mpf102 fets
if you had a choice between the two which would you prefer
for best performance ?
thanks

Think there is not much differents between them, as long as they are close matched.
Also I had some J310 fets... after testing them it seems the al where close in tolerants .. they also worked in the baracuda..
If I had to make a choice it is the 2N5485 I use, just a feeling...

.... it is as porklver explains, look at his explanation here post # 193, a few posts earlier..

Best regards.

Ap

[6666]

Hi AP
with all your testing with matched 2N5485 and Mpf102 fets
if you had a choice between the two which would you prefer
for best performance ?
thanks

[maikl]

What is the best for Q3 and Q4?

Hi Rom_1. It seems does not work very well Google translator (English - French). The best combination is Q3=2N5485 and Q4=MPF102. Best regards.

[Rom_1]

What is the best for Q3 and Q4?

[ApBerg]

Hi AP
thanks

sorry for my poorly worded question
what I was trying to ask was
what are the complete numbers on the chips
for example ne5534XYZ
and LM358XYZ

thanks
cheers

Hello,

Made a small test... for U2 I only have the Ne5534p ...

for U4 I tested 8 IC's, they als work and not much differents .... I like the LM358 (j4k527) the TLC272 and the lF442 ... some re-adjustment with the tune(threshold) potentiometer is needed , but then they al get good sens....

Best regards

Ap

[porkluvr]

If you have two 2N5485, use them for Q3, Q4 and use 2N5458 in less critical slot, say Q5 or Q12.

2N5458 is not really a good substitute for the sample circuit around U4 (partnering with 2N5485) but it might work dandy somewhere else.

[Rom_1]

Hi, new in this forum, i just received my baracuda kit from Silverdog. In my kit i have as Q3 a 2n5458 instead of the 2n5485. Can i use it to replace the 2n5485?
Thanks.

[DOOLEY]

good question 6666,

chip specs vary quite allot depending on the designation AFTER the "normal" part number we usualy only refere to.

only the other day , i happened to be looking at TL071's , 7 different designations ,

all with different max voltages , and different offset's (3 to 10 mV),

buying online can be a chance , poor / average / good spec.

only found the difference when on rs site.

i'll certanly be double checking the full part number in future

[6666]

Hi AP
thanks

sorry for my poorly worded question
what I was trying to ask was
what are the complete numbers on the chips
for example ne5534XYZ
and LM358XYZ

thanks
cheers

[ApBerg]

AP
just for interest would you mind telling me the exact part number on U2 and U4
that you used in your Bara please

thanks

Hello

For U2 I used NE5534 and for U4 the LM358 ....

Best regards.

Ap