MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

Sample/slew bg and ug query
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author Sample/slew bg and ug query
Pav
Hi, will be stuffing the sample/slew PCb this week and had a couple of questions

1) P5 of build guide states
>>You'll get better performance if the two LF398 devices are soldered to the board direct.

Why would this be?
Earlier the reason is said to be to make access for the adjacent caps. I tested an ic socket with the caps purchased with the pcb from synthbuilder and there is room for these specific parts with a socketed ic.

2) user manual p9 calibration of clk

>>Set the rate pot to the slowest setting and adjust CLK so that the CLK LED flashes at its fastest rate......etc.

Struggling to comprehend this instruction..losing brain cells every day. hmmm.....
Why set the slow to flash fast? And Does slowest setting not mean pot full counter clockwise ?

Thanks
Pav
Synthbuilder
Pav wrote:
P5 of build guide states
>>You'll get better performance if the two LF398 devices are soldered to the board direct.

Why would this be?

Physical space for the capacitors is one reason but the ones I supply will fit with most DIL sockets. However, the main reason is to do with leakage. Sample and hold circuits when in hold mode need to keep that capacitor from discharging or charging. That's impossible but it is best to try and reduce the current loss or gain as much as possible. To do this one needs to keep all the conductors (copper tracks on the board & IC connections) around that capacitor as short as possible and away from any other tracks carrying different voltages. Adding a DIL socket increases the length of the tracks and can increase leakage. The best performing S/H are often built with the hold capacitor parts assembled in the air.

Whether using sockets or not makes any real difference to the modules performance is not something I've measured. The LF398 isn't a brilliant S/H but it suffices for the purposes that the Sample/Sles module was designed for - that is, to generate random CV events for modulation purposes, and other sample/hold effects.

Quote:
Why set the slow to flash fast? And Does slowest setting not mean pot full counter clockwise ?


The CLK trimmer is set firstly to get the clock oscillator moving fast. This is not really part of the trimming process but just a way of getting you to find out which is the fast end of the trimmer and which the slow. If we started at the slow end the oscillator can lock up and not move - the LED would still be lit which may give the impression the clock is running very fast when in fact it's stopped.

So find out which end of the trimmer is fast, then turn it the other way and the clock will probably stop. Now move it very slowly back towards the fast end until the voltage on pin 8 of U3 gets to around -2V.

Tony
Pav
Thanks for the clarification
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Page 1 of 1
Powered by phpBB © phpBB Group