<wpwrak>
today, i got a shipment from digi-key, containing three little lithium button cells. the warning labels on the box made it look as if it contained a nuclear warhead ;-)
<kristianpaul>
wpwrak: what you need lithium button cells ?
<kristianpaul>
self powered atben? :-)
<kristianpaul>
s/what/why
<kristianpaul>
damn psu
<wpwrak>
naw, for powering the atben, i'd just feed back the regulator output into the input :)
<wpwrak>
it's to experiment with chargeable lithion cells. i basically want to prove they're not good at delivering the kind of power i want.
<kristianpaul>
if somebody here get are involved on making a laptop like thing with rechargable batteries, PLEASE avoid tampered PSUs...
<wpwrak>
(relatively high current, pulsed, but with fairly wide tolerance on the voltage. so the primary li cells are okay, but i have my doubts about the secondary ones)
<kristianpaul>
chargeable, sound nice :)
<wpwrak>
what's a "tampered" psu ?
<kristianpaul>
he :p
<kristianpaul>
i have a mips laptop, the psu is kinda small and easilly breaks when you try open it..
<kristianpaul>
so is no tampered.. sorry
<kristianpaul>
and dont loose easy.. argh
<kristianpaul>
i just need to change the broken power cable..
<kristianpaul>
oh wel..
<kristianpaul>
if the thing will break why they just dont make it swichable, like the connector for the main..
<kristianpaul>
looks for his coping saw
<kristianpaul>
finally surender, the winner a scalpel :)
<kristianpaul>
may be i'm not used right term, but this psu box was not actually glued
<kristianpaul>
sealed it looks like..
<kristianpaul>
but the scalpel make trought :)
<wpwrak>
saves a few picocents. make a hundred million units and we're talking about real money ;-)
<kristianpaul>
sorry i lost the track..
<kristianpaul>
was that about the cells?
<wpwrak>
naw, your cheap power supply
<kristianpaul>
ah :)
<wolfspraul>
hey this is slightly off-topic here but then not really
<wolfspraul>
wpwrak: did you see the reports of people on the openmoko list about US carriers texting and calling FreeRunner users that their phone cannot continue to be used on the AT&T network?
<wolfspraul>
quite interesting
<wpwrak>
wow
<wolfspraul>
I think we will see this more in the future.
<wolfspraul>
yes
<wolfspraul>
even intercepting phone calls and redirecting the renegate users to call centers
<wolfspraul>
the reason why I think we will see more of this is because networks are caught up in a jungle of old/legacy devices
<wpwrak>
is there an indication of the reason why they tell them to stop using it ?
<wolfspraul>
and have a hard time updating and supporting a myriad of devices with their basestations
<wolfspraul>
I think it's a general tightening of standads
<wolfspraul>
standards
<wolfspraul>
GSM is getting old, so the more old devices you can kick out the easier you can upgrade your network
<wolfspraul>
the basestations
<wpwrak>
and where was this posted ? didn't even know the lists were up again
<wolfspraul>
otherwise the need to support a seemingly infinite number of legacy devices holds you down and creates support costs
<wolfspraul>
I've read some reports in that direction, but that's the first evidence from real FreeRunner users
<wolfspraul>
Joshua is also an avid NanoNote user :-)
<wpwrak>
okay, so they basically want to migrate users away from GSM. not FreeRunners per se.
<wolfspraul>
oh sure, they probably don't even know about 'FreeRunner'
<wpwrak>
the last carrier supporting GSM may be in for a surprise, with all the FreeRunner users migrating to them and all of a sudden becoming a large group ;-))
<qi-bot>
[commit] Werner Almesberger: labsw/: schematics, layout, and header.fpd update (in progress) (master) http://qi-hw.com/p/wernermisc/c0bfec4
<kyak>
xiangfu: so, the release image is probably being compiled right now? :)
<xiangfu>
kyak, one small problem about nanonote-files. :(
<kyak>
yeah, a strange problem - didn't see it before
<xiangfu>
kyak, yes. I setup a 'date' setup in uci-default . setup the date to the day of build when first boot.
<xiangfu>
kyak, that case that problem.
<xiangfu>
I have update nanonote-files , using 'cp' not 'mv' may fix the problem
<wpwrak>
DocScrutinizer: btw, if you have a "LINE" input/output and a "TAPE" input/output, would you consider them to be compatible ?
<DocScrutinizer>
hm?
<wpwrak>
DocScrutinizer: and are there any "standard" voltage levels for "LINE" ?
<wpwrak>
(audio)
<DocScrutinizer>
yes, yes, iirc now 1V5 RMS, formerly 0V775
<DocScrutinizer>
>>Die Impedanzen und Pegel sind bei analogem Audio nicht einheitlich, so dass es bei Geräten verschiedener Hersteller, gelegentlich sogar bei Geräten unterschiedlicher Serien desselben Herstellers, zu Lautstärkeunterschieden bis hin zu verzerrenden Fehlanpassungen kommen kann<<
<wpwrak>
it's reassuring to know we live in a perfect world ;-)
<DocScrutinizer>
1V550 RMS
<wpwrak>
yup
<wpwrak>
it's funny. my Sony stereo, definitely a CE device, outputs about 1.3 Vpp
<wpwrak>
so i wonder if sony added some extra oomph or whether wikipedia is a bit on the low side for consumer electronics
<DocScrutinizer>
err, how's 1.3 Vpp on the high side and 1.550V RMS on the low?
<DocScrutinizer>
actually 1.3Vpp sounds like a proper ~0dBV level
<DocScrutinizer>
inputs should cope with at least +6dBV
<wpwrak>
i'm still puzzled about what ARD have to do with _line_ levels ;-)
<DocScrutinizer>
:shrug:
<DocScrutinizer>
anyway, I seem to recall it's been 0.775 in former times, and eventually changed to 1.5, of whatever unit RMS or Vp(p) or whatever
<DocScrutinizer>
and I'd think an input shall handle 2Vp while an output shall at least provide 0.5Vp
<DocScrutinizer>
as there's no strictly defined levels, and usually you always have a volume control somewhere, there's rarely an issue as far as I can tell
<wpwrak>
yeah. i'm trying to figure out if M1 does things right or not.
<DocScrutinizer>
on "proper" equipment with some ~1.xx Vpp-ish line-out, you rather have a S/n ~80dB which should be good enough
<wpwrak>
yeah, i think M1 usually doesn't care so much about audio quality anyway. at least not in the current uses.
<wpwrak>
audio is mainly used to modulate video effects. nobody will see a few dB ;-)
<DocScrutinizer>
if you want to do it the professional way, you get a RCA receptacle that's floating GND, and an OPAMP plus some birdseed and a potentiomenter, to lowpass-filter -3dB@24kHz and balun the RCA in, and highpass-filter@5Hz
<DocScrutinizer>
ooh, so I could've saved to type the prev line
<DocScrutinizer>
wpwrak: hey, you know you should spend another 1kR series, plus 2 clamp diodes, for the line-in when they go to WM-codec?
<DocScrutinizer>
and you need sth like a 100nF...1uF decoupling C
<DocScrutinizer>
and a 50k to GND after that C
<DocScrutinizer>
and a 50pF parallel to that 50kR
<wpwrak>
sure ?
<DocScrutinizer>
should look into WM9707 DS for application notes ;-D
<wpwrak>
M1 has an 1:2 input divider (2 x 6.8 k), then a 1 uF DC block
<wpwrak>
where did you find them ? :)
<wpwrak>
fig. 18 "RECOMMENDED EXTERNAL COMPONENTS" keeps things rather simple
<DocScrutinizer>
make the (de)coupling C 470nF ;-)
<wpwrak>
hmm, i somehow don't think anyone will go for that at the moment, unless something really serious pops up
<DocScrutinizer>
and seems the chip has internal pulldown R so the 50kR also is moot
<wpwrak>
but indeed, the data sheet says 470 nF
<DocScrutinizer>
so what's left is are the 2 clamping diodes, a 50pF parallel to one of them, and a 1k in front of that towards the RCA receptacle
<DocScrutinizer>
s/ is//
<DocScrutinizer>
maybe even a bead between the clamp diodes + 50pF junction and the C16/17
<DocScrutinizer>
RF on a ADC input can give you really weird effects ;-D
<DocScrutinizer>
and ESD is a must
<DocScrutinizer>
so you want the diodes and the R, the C, and probably the bead
<DocScrutinizer>
I'd actually place C17 directly after the input, then the 470R...1K series, then the 2 diodes and 50pF, then the bead to pin23
<DocScrutinizer>
>> The devices performance with AVDD = 3.3V is shown in Electrical Characteristics. In 3.3V analogue operation, mid-rail reference scales to 1.65V. All ADC and DAC references are 2/3rds of their nominal 5V value. Input and output signals that are 1Vrms in 5V applications, scale to 660mVrms in 3.3V applications. It is not possible to produce an undistorted 1Vrms output by using the mixer PGA gain whilst running from a 3.3V analogue
<DocScrutinizer>
supply. <<
<DocScrutinizer>
I did an error above, when I assumed symmetrical AVDD-GND-AVSS of +/-3V3, and based my dB estimations on that
<DocScrutinizer>
you can tell from >>Â Â [A]-> diode -> VSS <<
<wpwrak>
let's see if there's ESD ...
<wpwrak>
nyet :-(
<DocScrutinizer>
not on the chip. Chip never have ESD for 'real life'
<wpwrak>
yes yes, i know what you mean ...
<wpwrak>
it's jack -> 1:2 vivider -> DC block -> chip
<wpwrak>
s/vivider/divider/
<DocScrutinizer>
hmm
<DocScrutinizer>
how'd you do a 1:2 divider there?
<DocScrutinizer>
sound like trouble
<wpwrak>
6k8 serie, 6k8 to GND
<DocScrutinizer>
the chip's input is specified as Z>=10k
<DocScrutinizer>
that's not a 1:2 then
<wpwrak>
Audio GND is now equal to digital ground, after a bead connecting them made the whole box go belly-up when i connected it to my stereo :)
<DocScrutinizer>
but you never know, chip Z can also be >>10k
<DocScrutinizer>
is's just specified to be >=10k
<DocScrutinizer>
toldya a devicer there sounds like trouble, esp in the 1:2 ... 1:10 range
<DocScrutinizer>
decider
<DocScrutinizer>
deducer
<DocScrutinizer>
anyway a 50pF parallel to the 6k8 load of the divider shall suffice for RF rejection and ESD
<wpwrak>
so no varistor, clamp, or zener ?
<DocScrutinizer>
nah
<wpwrak>
kewl
<DocScrutinizer>
it's an analog input in the end of the day
<wpwrak>
lekernel: are you reading ?
<wpwrak>
lekernel: sounds like a worthwhile addition for rc4
<DocScrutinizer>
I guess they have some minimal clamping in chip anyway
<DocScrutinizer>
wit another 12kR in series this should survive OV
<DocScrutinizer>
well 6.8 series, 6.8 parallel
<DocScrutinizer>
maybe increase the 50pF to make a lowpass 3dB@20kHz
<DocScrutinizer>
so it eats more energy of any surge
<DocScrutinizer>
I gather it's a mere signal analysis input for controlling purposes? then the divider issue also is rather irrelevant as you'd get away with sth like 20dB S/N there
<DocScrutinizer>
you'd not want to listen to it, but for controling some parameters of a GFX algo it's just fine
<DocScrutinizer>
you possibly even would *want* to cut frequencies >10kHz for this purpose. Results in less aliasing concerns
<DocScrutinizer>
waves
<DocScrutinizer>
meh, wolfson had great whitepapers about e.g analog vs digital ground and how to design layout for that. Vanished from their site
<DocScrutinizer>
I don't think beads were mentioned at the one pont where both connect ;-D