Patchwork Reloaded: Circuit Optimization and Board Layout.

[AndrewT]

bd are To126 = reverse To220
MPSA are To92

The datasheets will confirm.

[454Casull]

digi-key carries for the BD139:

SOT-32-3, TO-126-3 (?)
TO-126-3 (Straight Leads)
TO-225-3

What's the difference between TO-92 and TO-92-3?

[MJL21193]

Hi 454,
The BD139 will be this on. It is the vbe multiplier and gets bolted down to the heatsink.

The MPSA18 is this one.

[454Casull]

Lead spacing for these caps?

CAPACITOR, 100nF C4, C16, CZ
CAPACITOR, 100pF C18
CAPACITOR, 1uF C9, C7, C8
CAPACITOR, 2.2uF C6
CAPACITOR, 220pF C10

And the 2SA1381, what hFE do I need?

[MJL21193]

Originally Posted by 454Casull

Lead spacing for these caps?

CAPACITOR, 100nF C4, C16, CZ
CAPACITOR, 100pF C18
CAPACITOR, 1uF C9, C7, C8
CAPACITOR, 2.2uF C6
CAPACITOR, 220pF C10

And the 2SA1381, what hFE do I need?

C4, C16 are ceramic bypass - NPO/COG. Pin spacing on board is 5mm.

CZ can be ceramic or film. Board spacing is 5mm.

C8, C9 are film. 15mm lead spacing.

C7 is film like this 10mm lead spacing.

C6 is similar to C7. It has multiple pin spacing, from 5mm to 16mm.

C10 can be silver mica or NPO/COG ceramic (what I'm using). Pin spacing is 5mm and 7.5mm

Get the "F" class for 2SA1381.

[454Casull]

I'd like to use X7R bypass caps because I already have them (and they're much, much cheaper). Do you think that downgrading will result in a tangible performance drop?

How about C18?

For C6, I'm assuming it's 5mm, 12.5mm, and 16mm?

Can I replace the 1N4148 with 1N4004 (higher specs)?

[454Casull]

C10 looks like it only has one pair of holes, and it seems to me that the pitch is something like 3.5mm?

Are there any caps whose tolerances are crucial, besides C10?

[454Casull]

C5 doesn't look like it's in the BOM at all.

What the hell is up with the 30 minute edit limit? Grrrr

[AndrewT]

If you are making a PCB then I advise that all the caps should have multi pin pitch options.

[MJL21193]

Originally Posted by 454Casull

I'd like to use X7R bypass caps because I already have them (and they're much, much cheaper). Do you think that downgrading will result in a tangible performance drop?

How about C18?

For C6, I'm assuming it's 5mm, 12.5mm, and 16mm?

Can I replace the 1N4148 with 1N4004 (higher specs)?

X7R for bypass are fine - I certainly couldn't hear a performance drop (maybe because it doesn't exist )

C18 is not on the design. See latest board layout above.

1N4004 will work as well.

Originally Posted by 454Casull

C10 looks like it only has one pair of holes, and it seems to me that the pitch is something like 3.5mm?

Are there any caps whose tolerances are crucial, besides C10?

Again, see latest board layout.
Nothing is critical. 10-20% for everything is ok (nice to have C5 5%). C10 is for input RF, tolerance is not critical.

Originally Posted by AndrewT

If you are making a PCB then I advise that all the caps should have multi pin pitch options.

Not really needed, these are common sizes and really wouldn't be a problem sourcing them. Laying out a board is hard enough without allowing for every conceivable cap size.