Pumpkin preamp - ordered by Steen , official making thread

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#1,021
jacco vermeulen said:
Junk Fuwed Book:

With 1000uf caps instead of 2200=> charge ripple without CRC still less than 100mV.
Use 1000uf and double the R21/R23/R24(a) value, 0.6W typies (Cheesecakes even go doublesided)

MUR1xx, just as fast.
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The pumpkin has C8 C10 C13 C14 - rated for 220-470uF and the Shunty has C2 2a 15 15a 16 16a rated for 1000 - 2200uF.

So assuming the same grade and series of electrolytic caps - what is the advantage or disadvantage of using a bigger vs smaller cap? Bigger cap = less ripple?

Still a noob

her shann
 
#1,022
Rough formula:

Vripple = [ 1700 x Current(max) ] / uF number.

A smaller same brand/type cap is cheaper and has a higher ESR number.
By increasing the resistor value the number R*C remains constant, same corner frequency, same noise reduction before entering the 1st. reg. stage.
Does mean the voltage drop across the series resistors is higher, picking a transformer with 1 Vac higher secondaries straightens it out.

(btw: USA guys looking for fancy food spindle ptfe caps should type in : Voltronics A1 series, the big vendors likely have them for at least $25 the pop)
 
#1,034
Zen Mod said:



:djinn: :hphones: :hypno2: :grouphug: :spin: :cheers: :cheers:

you forgot to say that you have few smoked resistors ( my last add in Cook......) and that you also have CM choke in it .......
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Yea, I told You. R23 and R23A were problematic. At the moment I put 2 in paralel (1/4 W) of 47 Ohms instead of R23 and R23A. The rest of the resistors are according to the previous release of the Cook Book. Chokes I had, so lets keep it there 😉
 
#1,039
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