Poor Serbian Man Optical Volume Control

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here it is ;
result of collaboration of few Serbian DiyAs - one engineer mind (sp300b) and one sick mind (ZM)

as usual - ZM does all back of napkin drawings and some testing , sp300b does some much more testing and pcbs ;

find schematics enclosed ; pcbs are in stage of testing ..... in fact - pcbs for PSM Optical Volume

are ordered , and pcbs for separate buffer are in developing ;

first - PSMLS schematic ; nice drawn by sp300b ( not in my usual gorgeoushandscribing way )

it's intended either for stereo balanced or stereo unbalanced ( omitting
4 LDRs)
 

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Official Court Jester
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separate pcb for buffers and dedicated supply/reg will contain 4 buffers

.........4 pcs of good ole JC buffer , as sp300b's wish ...... even if I intent to use real poor man's choice - pair of J310 jfets in "source follower up/CCS bellow" configuration .....

this time my fave back of napkin drawing
 

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steenoe said:
ZM & Spavleski, great job:cool:
Where can we order, I wanna try some of that lightnin' stuff.

Nice little supply for the buffer.


:)


not yet , ya kwayzee danske ;
I have enough duties regarding our local GB ........... and just when first pcb be tested I can tell that's OK

PSM LS pcbs are on fab , buffer pcbs are still in work

reg for buffer is nothing special , except one little trick ,and even that is boiled water ;)
I'm sorta shy-proud with LS circ ..... buffer reg is trivial




DVBjunky said:
Me too...me too!

ZenMod, will we get a detailed description of the "Schematic" of the PoorSerbianManLightspeed.....whats different compared to the lightspeed Mk2 or Papa´s LDR?

You like the J310 jfets? Tell us more :)

Thanks in advance.

cheers

Alan


difference between Mk's of Lightspeed is ( at least as I see it ) is that Mk1 is series fixed resistor/LDR to gnd , and Mk2 is LDRs in both positions .....

so - solution here is same as in MK2 and in Papa's version - LDRs in both positions , so just reg is different , with few other tricks in it .

here is different , comparing to Papa's only that we used rather primary current regulator than voltage regulator ..... in fact - there is not much different , but I have impression that this variant is pretty good ;

NB - I didn't analyzed Papa's circ in deep , so I can't tell right now is it current or voltage oriented (even if that's just matter of wiev) ;
I just goes for different solution ...

parallel resistor to lin pot is trick borrowed from Eliot Sound ( his site is treasure indeed)

regarding J309/310 jfets - I'm using them in my :Pumpkin:

I see them as 2SK170V ...... on steroids :clown: