Pumpkin preamp - ordered by Steen , official making thread

[luvdunhill]

(it's probably time for one more Papalike RIAA ........... ) [/B]

speaking of which... Jacco, the eagle has landed.. I repeat, the eagle has landed.

10-4

 

[jacco vermeulen]

got ya, sounds more like a crippled duck.
Instead of ETA they should give the EYA.

 

[Zen Mod]

speaking of which... Jacco, the eagle has landed.. I repeat, the eagle has landed.

10-4

got ya, sounds more like a crippled duck.
Instead of ETA they should give the EYA.

?

 

[noelectrix]

last ot.
holger, d3 is "just" fast. buy d700. same pics, but slower (slow between pics)

greets
stefan
edit d700 instead of d300

 

[luvdunhill]

Zen Mod: a certain part-monger sent me some little blue boxes for a RIAA filter.

Jacco: is there a third significant digit that I can aim for on those 3 capacitance values? I have access to a capacitance bridge at my dad's university lab, but it probably hasn't been calibrated in years probably better than nothing though.

Zen Mod: what to do with the CT and electrostatic shield wire from transformer (I don't have them yet, but... still would like to know) do they go to the board, or some sort of star ground through a thermistor?

 

[Zen Mod]

......
Zen Mod: what to do with the CT and electrostatic shield wire from transformer (I don't have them yet, but... still would like to know) do they go to the board, or some sort of star ground through a thermistor?

shield winding from xformer goes directly to safety ground (case ) .

CT goes to safety ground/case either via NTC ........... or via NTC

 

[jacco vermeulen]

Cig-Lighter,

check your email.

Building a capacitance meter with <1% accuracy is pretty easy, bet you a nickle there are plenty of schematics on the web.
0.1% is possible too, becomes a bit pricey though.
Calibrating a cap-meter is peanuts with a reference capacitor.

 

[luvdunhill]

my little transformers just shipped from hong kong! it won't be long before the fireworks (either figuratively or not) begin!

 

[Assesears]

G'Day Zen Mod,

Please can you tell how to work out the RC ratio, from cookie book

note 2 . use mica if you find ; value must be scaled according to value of R5/R6 ; if
you decrease/increase value of R5/R6 then increase/decrease value of C1/C2 to
preserve approx. same RC ratio.

Cheers

 

[Zen Mod]

G'Day Zen Mod,

Please can you tell how to work out the RC ratio, from cookie book

note 2 . use mica if you find ; value must be scaled according to value of R5/R6 ; if
you decrease/increase value of R5/R6 then increase/decrease value of C1/C2 to
preserve approx. same RC ratio.

Cheers

R5/R6 =100K
C1/C2 = 5pF

so - RC = 100Kx5pF=5x10^-7

that's in fact connected to corner frequency of that RC pair

simple - if you decrease R5/R6 to 47K , you must increase C1/C2 (to preserve same multiple ) to ~ 10pF

so- C1/C2 = 5x10^-7/47K = 10p6

clear enough ?

 

[Assesears]

That will do,
Cheers

 

[luvdunhill]

one Shunty is ready. For some reason, I got 500mA fuses.. I'm not sure why I did this.. perhaps I knew something? Anyways, what does Pumpkin require fuse-wise in Shunty? 300mA?

 

[Zen Mod]

one Shunty is ready. For some reason, I got 500mA fuses.. I'm not sure why I did this.. perhaps I knew something? Anyways, what does Pumpkin require fuse-wise in Shunty? 300mA?

ya teasing me ............... or ya teasing me ?



value is in Cook Book

 

[luvdunhill]

heh, I think I got 500mA from some BOM around here ... anyways... I'll post some pictures soon. I finally got things mounted on those heat sinks, but it was a pain.

 

[Zen Mod]

heh, I think I got 500mA from some BOM around here ... anyways... I'll post some pictures soon. I finally got things mounted on those heat sinks, but it was a pain.

BOM ?

who need a stinkin' BOM .................

 

[luvdunhill]

so, I looked around cannot find any 5x20mm 300mA slo-blo fuses locally... but I did find for a quarter a Corcom 10VR6 filter. It might be too big for a Pumpkin, but what do you think? Sure is shiny...

 

[Zen Mod]

so, I looked around cannot find any 5x20mm 300mA slo-blo fuses locally... but I did find for a quarter a Corcom 10VR6 filter. It might be too big for a Pumpkin, but what do you think? Sure is shiny...

so - just put those 500mA in ......

 

[Manu]

JUst a question : how will Pumpkin behave with ONO?
Well?

Manu

 

[Zen Mod]

JUst a question : how will Pumpkin behave with ONO?
Well?

Manu

like a Cat and Dog ....... if they grew up together .....

Papalike ONO
Papalike

ya teasing me .......

 

[luvdunhill]

so so so... I finally got all the parts... checked a few things and noticed that tabs on Shunty darlingtons are shorted to each other .. suppose this is correct.. other IRF tabs are isolated from each other and the darlingtons... then, I plugged in the trafo (with fuses removed) and got 103VAC at the input and +- 70VDC at the fuses. ok, so I installed the 2 resistors and put one fuse in ....... um.. then I had like 2-3 VDC at the output (and at the fuse) and 103.4 at the other side where the fuse was missing (but after bridge)... ummm... i'm assuming this is normal? just I just try it with both fuses installed?