Pumpkin Shunty begins....

[malgre]

Say, I know you are using same BOM, it appears it lists R10, 10a, 11,11a as 6.81k, while cookbook shows (correct of course) it as 33k. 6.8k should be R9, 9a, 26, 26a. Looks like they skipped the 33k..Also don't show R9, 9a, 26, 26a at all.

Russellc

Thanks for the heads up... I've got those correct - I basically used that BOM for part number ideas, then went through the cookbook list, and I double checked the cookbook list (and the conversations here) before the order. In hindsight, I ended up choosing different parts for much of what is on that BOM, but it was a big help in getting started.

Tod

 

[Russellc]

Thanks for the heads up... I've got those correct - I basically used that BOM for part number ideas, then went through the cookbook list, and I double checked the cookbook list (and the conversations here) before the order. In hindsight, I ended up choosing different parts for much of what is on that BOM, but it was a big help in getting started.

Tod

Precisely how I caught it. Good eye. I still have a bunch of odds and ends to order so no big deal.

Russellc

 

[Zen Mod]

when in doubt , just buzz here

 

[Russellc]

when in doubt , just buzz here

Thanks, much appreciated.

Russellc

 

[malgre]

Pumpkin bypass caps question...

ZenMod,

While I wait for the Shunty parts to arrive, I'm looking into other parts, and, for the Pumpkin, I was wondering about the bypass caps (C11,C12) for the output coupling caps (C4,C5) - one point of view is that you should just get a nice coupling cap and forgo any bypass cap, for example: "Bypass capacitors create multiple signal paths with multiple time constants. These time constants are very short but they can still be heard as a smear or overall loss of focus." <--(I've read basically this in a few forums.)

Any advice/experience on how to pick C4,C5 for this design? I could see splurging (a bit, nothing with beeswax and gold ) for a nicer film cap there, and maybe losing C11,C12 as one approach. Or standard box film and nicer bypass. Or just boxes all around (prob Wima) and forget it.

Tod

 

[Zen Mod]

my fave bypass cap is MKC , polycarbonat , as big as I can squeeze in physically
and yes - I can hear bypass , when done properly , with positive results

I'm just amused with anal approach from yore - several bypass caps , each having 10% size of preceding one

btw. cheap and hard to beat solution is Elna Silmic 10uF + 1uF MKC

proven exactly in M2 , and several gadgets before and after

 

[Russellc]

Zenmod, question on C2, 2a, 15, 15a, 16,16a

2 choices, 63v and 100v: What do you think of these, performance and long life most important:

UHW1J152MHD Nichicon | Capacitors | DigiKey

UPW2A102MHD Nichicon | Capacitors | DigiKey

UHW2A102MHD Nichicon | Capacitors | DigiKey

http://www.mouser.com/ProductDetail...18FY5yBazwPd0TzukpWaRto/dpqCMicQgi6OQJrNnCQ==

I probably missed good one, if so I am all ears!

Russellc

 

[Zen Mod]

all of these are good

practically - put there anything you fancy ( or already have in drawer) in size from 470uF to 2200uF

important is decent quality , so decent name on them

even with trice 470uF filtration is sufficient and - what's most important - you'll not hear difference if you put trice 2200uF

who sez I'm not flexible

 

[Russellc]

all of these are good

practically - put there anything you fancy ( or already have in drawer) in size from 470uF to 2200uF

important is decent quality , so decent name on them

even with trice 470uF filtration is sufficient and - what's most important - you'll not hear difference if you put trice 2200uF

who sez I'm not flexible

I think 63 volt sufficient for the Antek transformers I am using, is there anything to the 10000 vs 5000 hour life, or ripple differences? plus I assume that 100v would not be as stressed as 63 volt giving longer life or am I off base here as usual?

Russellc

 

[Zen Mod]

well , bigger is better

 

[evanc]

well , bigger is better

So says my wife..... Couldn't resist.

 

[Zen Mod]

ripple difference will not show up , not in this range of currents and in this level of later regulation

 

[malgre]

my big shunty parts order arrived

Always like a mini-christmas when a box full o' parts arrives! And the backordered heatsinks from Allied just shipped. So, maybe I can actually build the shunties this weekend - that would be nice, I'm pretty tired of the parts ordering and would like some results!

Tod

 

[Russellc]

Allied came through and the two smaller sinks have arrived, so all sinks are now in hand

While the larger sinks have enough meat on them for drilling and tapping, the little ones are very thin.


To those who drilled and tapped these smaller sinks, what size hole did you tap? It must be tiny?

Russellc

 

[Zen Mod]

I presume 2mm will do for majority of heatsinks

btw. I forgot to say , you can even use self-tapping screws , if you find them in local store ;


or - regarding small heatsinks - just leave them without screws , glue some isolation spacers underneath

 

[Russellc]

Thanks Zenmod!

Russellc

 

[Russellc]

Zenmod, while waiting on last of Shunty parts I am looking at the Pumpkin boards. Comparing required resistors to on hand, I noticed R7 on Pumpkin board has 3 solder pads. An extra one in middle.

Looking at schematic, at first I thought it was R14, but on board has its own 2 pads.

Brief Reading of cookbook didn't reveal anything.

I am sure it will become obvious at some point, but I have to ask, what is this pad for?

Russellc

 

[Zen Mod]

look at other side of pcb ........

(that's VIA (metalized hole through which trace is changing plane) , ignore it)

 

[Zen Mod]

I'm glad you asked

always better to ask and be given with reply , than to have doubts ......... and possibly make some mistake later

 

[Russellc]

I'm glad you asked

always better to ask and be given with reply , than to have doubts ......... and possibly make some mistake later

Why I asked! I have made that "mistake" many times

Trying to get this fine pre done right first time....that itself may be first time!

Ignore it I will...Thanks as always,

Russellc