Sunday, February 19, 2017

ADC test

incomplete Σ Δ ADC -- since i don't quite grasp it's operation yet -- just to see where it goes . . .

the CLK not verified as opt. for this v. but for it's predecessor that was tracking the analog input with the analog summer - the D-Flop output was basically the same only it was without the U/D counter ...

the following shows the effect of resetting the U/D count to 0 after specific time interval (number of clocks)
--  the effect with pure*sine wave here is the "reset" (actually a periodic substraction of some constant) integrates the derivative of it* back to it* -- it's a lot of tedious testing to determine what to actually implement in circuit . . . but the following is showing the prev. test being on the right track

what is surprising here is that the lesser number of clocks gives better results ???


DAC test

CD4069 outputs are referenced to supply median

checking if such produces a linear ramp . . .
all fun of resolving a simple 3 - supply voltage divider (finding the formula for UX)

. . . checking if such produces a linear ramp in excel . . .
-- the value 1/2 used in LT Spice seems to be incorrect . . .


Sunday, February 12, 2017

Absolute Voltage 2

the followup of the prev. post -- tested the experimental reference + came up with a new 1

the near zero error gives us the "absolute" voltage ref. -- tough -- there's no information about it's response to varying temperature !!!


Thursday, February 9, 2017

some experimental 1.2V supply designs + rnd. osc. variant

Originally designed for 3-5V operation , also studied for 1.2V
as with the 555 --  the basic operating mode's to generate low duty pulses -- economizing the battery

 Hi precision supply -- preserving near ® precision and with added current limit

Simple not limited 1.2V linear voltage regulator

the Op Amp variant of the above " Hi precision supply" without current limiting
-- the design has a "new" type of adjustable voltage reference that has not especially been optimized nor tested for varying operating conditions !!! (i just needed one and simple here !fast (as in common))

+ some more : update 2017-02-13 (1-st time to break the ±1µV error !?)


Sunday, February 5, 2017

Thursday, February 2, 2017

LM308 macro model substitute

my component level models perform basically the same while .cir model doesnot quite get "there" (what's expected)

googling for substitutes didn't revealed any credible results so - going to error~trial ...

the following figure sows a TOP - dn list of most possible substitutes for the LM308

although the LTC1047 looks a better match by gain curve - then after reading the datasheets of the bad boy (LM308) itself and it's other 3 top substitute candidates the LT1366 seems to be preferred coz LTC1047 needs extra feedback capacitors and LT1880 is referred to as super ß Op Amp (the input sensitivity of such may be a likely source to some instability . . . maybe . . . . . . . . . the LM308 is supposedly not so calm as it's macro-model lets it show ???) - so the LM1366 may be too calm coz it's internal capacitors maybe not - anyway it performs near excellent at the following quick check !

semi theoretical - mathematical application test ...
-- just a quick pileup from scratch -- to get some idea of it's behavior / performance (if it's a right chip for the task and/or substituting . . .)