<whitequark>
ooooh, transistor failure modes, now it gets interesting
<wpwrak>
just when you thought they were invulnerable ? ;-)
<whitequark>
wpwrak: not quite, I was fully expecting something weird
<whitequark>
but I really want to understand how exactly did it fail
<whitequark>
it's no fun otherwise
<wpwrak>
ah, so you blew it up. you did add the diodes ? :)
<whitequark>
of course not, told you so!
<whitequark>
I'm adding them now though, since I understand how and why it failed
<wpwrak>
;-)) i did warn you when you mentioned the schematics, though :)
<whitequark>
I remember
<whitequark>
I thought about it even when designing it, but it was probably too late and the rational voice was ignored
<whitequark>
anyway, it's even good that it failed, since I now understand it better
<whitequark>
another thing: 1) my homebrewn boards stand up to rework pretty well (no delaminated traces) 2) investing in solder mask was wise
<wpwrak>
at least your experience puts the lingering question to rest whether this protection is really needed or whether we all just add it because "that's what one has to do", but it would actually be fine without it :)
<whitequark>
exactly
<wpwrak>
(rework) well, they better do :) even on my little anelok board i replaced the OLED with its wide FPC twice already, without a problem. (FPCs are fragile critters and don't like a lot of mechanical abuse, so while they were just flapping freely, their life was intense and short)
<whitequark>
huh, yeah, both transistors are broken down entirely
<whitequark>
conductive between any pair of pins
<wpwrak>
whitequark the transistor slayer ;-)
<whitequark>
ummmm
<whitequark>
I took a brand-new bc547 and C-E are shorted
<whitequark>
wat?
<whitequark>
I'm fairly sure this is not how transistors are supposed to work
<whitequark>
oh, nevermind, it was my error
<whitequark>
and such a stupid one I'm not even going to say which
<wpwrak>
(wat?) you don't know the tv series "buffy the vampire slayer" ?
<wpwrak>
ah, new transistor. i see
<whitequark>
"wat?" was about the shorted C-E pins
* whitequark
looks away
<whitequark>
I put it into the breadboard, completely forgetting that *solderless* breadboards have rows of shorted pins
<whitequark>
been years since I touched one
<wpwrak>
:)
<whitequark>
nope, after adding diode it still does not work, with almost exact same symptoms
<whitequark>
and the transistor seems fine, or at least the Vf of both junctions is the same as for new
<whitequark>
and it's not broken down
<whitequark>
so basically... initially, Vbe=1.3, Vce=8.7. after feeding a pulse to base, Vbe=0.6, Vce=8.0
<whitequark>
and the relay is on
<wpwrak>
your transistors are NPN or PNP ?
<wpwrak>
in any care, your Vbe looks quite wrong :)
<wpwrak>
#s/care/case/
<whitequark>
npn
* whitequark
scratches his head
<wpwrak>
what are you trying to send down Vbe ?
<whitequark>
um?
<wpwrak>
i mean what levels are expected on the base ? on = xxx V, off = xxx V ?
<whitequark>
oh
<wpwrak>
(before the resistor)
<whitequark>
0/5V
<wpwrak>
so the initial 1.3 V should be 0 V
<whitequark>
yes
<wpwrak>
and when you turn it "on", the base voltage drops. remarkable ;-)
<whitequark>
I mean, I measure 1.3V with base floating
<wpwrak>
a floating base means nothing :)
<whitequark>
so I've tried to look up a commercially sold kit with a similar circuit, they have a resistor divider at base
<whitequark>
which makes 0.7V out of 5V, and also pulls it down normally
<wpwrak>
a BJT is a current-defined device. as long as you have 0 current, your base could be anything (well, it will still settle to some value due to secondary effects)
<wpwrak>
pull-down is a good idea
<whitequark>
wpwrak: (current-defined) sure
<whitequark>
what I mean is, I don't understand why it functions as a *latch*
<whitequark>
that just seems absurd
<whitequark>
it's not a FET, when the base is floating, it must do the same thing regardless of what I did to it before
<whitequark>
assuming it's not fried
<wpwrak>
well, leave the base open (float) for now. then the relay is off, right ?
<whitequark>
yes
<wpwrak>
now connect 5 V to the base (through resistor). then it should turn on. does it ?
<whitequark>
yes
<wpwrak>
when you remove the 5 V and float again, does it turn off ?
<whitequark>
nope.
<wpwrak>
fascinating :)
<whitequark>
*exactly*
<wpwrak>
in russia, transistors have memory
<wpwrak>
if you force the base to 0 V, what happens ?
<whitequark>
nothing
<whitequark>
relay stays on
<wpwrak>
are you sure it's not a bistable relay ?
<wpwrak>
one thing to check: are your transistor pins really where you think they are ?
<whitequark>
neither of these mention that it's "bistable"
<whitequark>
I am sure, I've checked it with a DMM and it has two junctions between the expected pins
<whitequark>
and it matches the DS
<whitequark>
also, I've tried desoldering the transistor and triggering the relay manually
<whitequark>
so it is NOT bistable
<wpwrak>
ok
<wpwrak>
forcing base to GND and still having the relay on is ... interesting
<wpwrak>
did you connect to before or after the base resistor when forcing base ?
<whitequark>
connect to what?
<wpwrak>
GND to base
<whitequark>
oh, tried either
<whitequark>
same result
<wpwrak>
sequence: 1) all open. 2) apply power to system (relay off). 3) drive base through R to 5 V -> relay on. 4) float base (relay still on). 5) drive base to GND (relay still on). correct ?
<whitequark>
yea
<wpwrak>
can you monitor the overall system current throughout all these steps ?
<whitequark>
with mA precision, yes
<wpwrak>
for step 3, you can just use your system voltage (~ 9 V ?) so you don't need an external 5 V source
<whitequark>
24V
<wpwrak>
"system" the transistor plus relay board. let's eliminate any driving circuit
<wpwrak>
ah, quite high voltage
<whitequark>
ummm
<whitequark>
the current is... below what my adjustable PSU can measure
<wpwrak>
use a multimeter :)
<whitequark>
but the relay needs 18 or so mA to stay on
<whitequark>
wtf
<wpwrak>
more like 2 mA, i think (drop-out voltage)
<whitequark>
very interesting
<whitequark>
if I keep the base connected via a 2k resistor (in sum) to 24V, I see 2.5mA of current
<whitequark>
but the relay stays on either way
<wpwrak>
what's the other way ?
<whitequark>
ewhether the base is connected or floating
<wpwrak>
at 2.5 mA the transistor should let something in the order of 100 mA through. more than enough.
<whitequark>
ok, the PSU is lying
<whitequark>
it's 7mA just after turning it on
<wpwrak>
maybe it's not floating when it's "floating" ;-)
<whitequark>
... then 25mA while the base is high
<whitequark>
then back to 7mA
<wpwrak>
what's your transistor's current gain ?
<wpwrak>
7 mA should be plenty to keep the relay on
<whitequark>
it's bc547c, so 420..800
<wpwrak>
but just not quite enough to _turn_ it on
<whitequark>
sure
<wpwrak>
so you'd need about 10 uA on the base to turn the relay on. at 24 V that's about 2 MOhm. time to check for sneak current paths.
<wpwrak>
how careful were you with cleaning the board from flux residues ?
<whitequark>
I didn't
<whitequark>
my DMM shows about 19MΩ to +24
<wpwrak>
well, more like 40 uA, when we include the mystery 7 mA you start with. but that's still low enough for flux "connections"
<whitequark>
that still doesn't answer the question of why doesn't the relay turn off with base forced to 0
<wpwrak>
one thing after the other ...
<wpwrak>
disconnect power, connect base to GND, reapply power. what is the system current ?
<wpwrak>
oh, and your diode goes across the relay ? or across relay and transistor, or something like this ?
<whitequark>
only across the relay coil
<wpwrak>
good
<whitequark>
cleaned the board with dimethoxymethane, same result
<wpwrak>
is system current is still high when starting with base to ground, then the next step would be to remove the transistor and see what happens
<wpwrak>
since it behaves as if there was a path in parallel to the transistor
<whitequark>
the resistance went under what my DMM can detect
<whitequark>
well, I have second relay without the transistor
<whitequark>
on the same board, which behaved exactly same
<whitequark>
can check it
<wpwrak>
you flux is friendly, being in the 10+ MOhm range. you ought to try one of the nastier ones some day, which go below 1 MOhm. they do great things to reset lines.
<whitequark>
ouch. good thing my PSU is current-limited
* whitequark
accidentally shorted it with DMM lead
<whitequark>
nice flash
<wpwrak>
yes, that's why we use lab power supplies and always set the maximum current to something not too far above what we expect to need ;-)
<whitequark>
*facedesk*
<whitequark>
fuck.
<wpwrak>
what was it ? :)
<whitequark>
you see, the board is nicely symmetric...
<wpwrak>
+/- reversed ?
<whitequark>
oh no
<whitequark>
X1/X4 swapped
<whitequark>
it behaved like a latch because lol, I assembled a latch, essentially
<wpwrak>
hmm, i don't have the schematics in sight
<wpwrak>
not sure how swapping X1/X4 would turn it into a latch ... well, if K1 is open, maybe fun things could happen with ground
<whitequark>
thought about that, yes
<whitequark>
oh. open
<whitequark>
well, nevermind, doesn't matter
<whitequark>
it's STILL a latch
<wpwrak>
reliable russian technology. no matter how much vodka you had and where you connected things, it always works the same way
<whitequark>
but why is it a latch?!!
<wpwrak>
did you do the base-to-ground-when-applying-power test ?
xiangfu has joined #qi-hardware
<wpwrak>
oh, and you have two K1 in your circuit
<wpwrak>
and three K2
<whitequark>
wait
<wpwrak>
ah, that's all the relay
<wpwrak>
weird symbol without the connection
<wpwrak>
which one are you testing ? K1 or K2 ?
<whitequark>
K1
<whitequark>
so I shorted base to emitter
<whitequark>
it still eats 7mA
xiangfu has quit [Ping timeout: 264 seconds]
xiangfu has joined #qi-hardware
<whitequark>
desoldered the transistor. 0mA
<whitequark>
soldered the transistor and literally left the base floating in air. 12mA
<whitequark>
insanity. there's thousands of variants of this circuit on the web
<wpwrak>
i strongly suspect your transistor is somehow connected the wrong way
<wpwrak>
behaviour would still seem odd, though
<wpwrak>
which transistor is it again you said ?
<whitequark>
bc547c. marked as "C547C"
<whitequark>
btw, you can actually connect the npn transistor in reverse (i.e. swap C/E) and it would still kinda work, although with lower hFE
<whitequark>
let me try to reproduce this on the breadboard...
<wpwrak>
(reverse) yes
<whitequark>
...
<whitequark>
well
<whitequark>
if I indeed connect it in reverse, then it has an idle current of 12mA
<whitequark>
which matches what I observe on that board..
<whitequark>
now, how did this even happen? the transistor has legs bent that they have a "triangle" footprint. the board, same.
<whitequark>
what the FUCK
<whitequark>
Eagle has the footprint in revers
<whitequark>
sure enough, now it works
<wpwrak>
never trust a footprint you didn't design yourself ;-)
<whitequark>
and especially not the ones I designed myself
<whitequark>
since I have attention span of a squirrel on meth
<wpwrak>
i trust the ones i designed because i know that they may be wrong and i have to test them. so they're all properly tested :)
<wpwrak>
besides, with fped it's pretty easy to review the critters
<whitequark>
it's not exactly complex with eagle, it just never occured to me that BC547 can come in two mirrored footprints, both asymmetrical in a way that would prevent you from misplacing them
<whitequark>
at least the transistor survived more than 50 cycles
<wpwrak>
(that's also roughly what you see on the screen with fped.)
<wpwrak>
i had my transistor experience with gEDA. in kicad i actually found that the stock libs matched each other and reality fairly well
<wpwrak>
but you sometimes got odd shapes
<wpwrak>
not necessarily incorrect but still odd. e.g., standard package X, but from a part with weird thermal requirements, so the footprint for all X is like that
BerryHalsak has joined #qi-hardware
jekhor has joined #qi-hardware
wolfspraul has joined #qi-hardware
sb0 has joined #qi-hardware
BerryHalsak has quit [Remote host closed the connection]
<whitequark>
crap. I completely forgot
<whitequark>
the control board has the *signal* pin hardwired to +5V, and it pulls the *ground* pin down
<whitequark>
which is kind of really weird but oh well
<whitequark>
so I basically have a logic OR between "spindle CCW" and "coolant pump on"
<whitequark>
...
pcercuei has joined #qi-hardware
<whitequark>
seems like a rev.B is in order
bartbes has quit [Quit: No Ping reply in 180 seconds.]
bartbes has joined #qi-hardware
jekhor has quit [Ping timeout: 264 seconds]
rz2k has joined #qi-hardware
xiangfu has quit [Ping timeout: 244 seconds]
xiangfu has joined #qi-hardware
xiangfu has quit [Remote host closed the connection]
lamrz has joined #qi-hardware
rz2k has quit [Read error: Connection reset by peer]
tumdedum has quit [Ping timeout: 240 seconds]
tumdedum has joined #qi-hardware
rz2k has joined #qi-hardware
lamrz has quit [Ping timeout: 252 seconds]
lamrz has joined #qi-hardware
lamrz has quit [Quit: Leaving]
xiangfu has joined #qi-hardware
kilae has joined #qi-hardware
xiangfu has quit [Remote host closed the connection]
<whitequark>
buuut it would be trivial to write an ULP that outputs that. maybe someone even did it
jekhor has joined #qi-hardware
<whitequark>
wpwrak: why the question? neo900?
<roh>
well.. you really now if all footprints are ok if you soldered the first prototype and it does work without reworks ;)
<roh>
in the end.. one would even need to check reality to documentation since the latter may be wrong from time to time
<wpwrak>
whitequark: yup. collecting arguments against the lame bird, just in case there's an opportunity :)
<wpwrak>
roh: and yes, that's the ultimate test :) actually, not even then you're sure since you may have footprints that happen to work but aren't really good and will give you yield headaches. or the fab silently fixed some problem for you but the next fab won't be so nice ...
<wpwrak>
roh: but with all the measurements you can at least make sure you draw what's in the data sheet. big step forward :)
jekhor has quit [Ping timeout: 240 seconds]
<wpwrak>
also, you can see all the measurements at once. not having to hunt them down interactively with some measurement tool
lamrz has joined #qi-hardware
lamrz_ has joined #qi-hardware
lamrz_ has quit [Read error: Connection reset by peer]
lamrz has quit [Read error: Connection reset by peer]
lamrz_ has joined #qi-hardware
lamrz_ has quit [Read error: Connection reset by peer]
lamrz has joined #qi-hardware
lamrz_ has joined #qi-hardware
lamrz has quit [Ping timeout: 244 seconds]
pcercuei has quit [Ping timeout: 240 seconds]
lamrz__ has joined #qi-hardware
lamrz_ has quit [Ping timeout: 252 seconds]
<wpwrak>
ttataa .... big thunderstorm coming. if that sort of weather moves north, they'll need snorkels at the world cup
<larsc>
ah yes, the latest buzz, the internet of things
<ysionneau>
yes that's just buzzword you don't care about :p
<ysionneau>
that's a chip, you just do whatever you want with it :p
<ysionneau>
I suspect those words are only there for search engines
<larsc>
everybody goes crazy about the internet of things recently
<larsc>
I guess some market research institute said that this is going to be the next big thing
sb0 has quit [Ping timeout: 264 seconds]
<ysionneau>
it could be honestly, if you have a good idea for a cool thing to connect to internet
<ysionneau>
so far I've seen none
<ysionneau>
so far most "small devices" use bluetooth or BLE and don't access internet directly
<ysionneau>
and have small battery life
<wpwrak>
in an occult ritual around 1952, five satanists brought the Thing into the pentagram. the Thing snarls and hisses. the arch-satanist, with a loud voice, proclaims, "Things, I name thee NSA !". thus, what traitor Emmanuel Gol... errr, Snowden, revealed, is merely The Thing claiming was what always has been his by rights.
* ysionneau
gives a shot of tranquilizer to wpwrak
<ysionneau>
there there :p
<wpwrak>
;-)))
<wpwrak>
i think the customary procedure would be to sing "warm kitty" :)
sb0 has joined #qi-hardware
<ysionneau>
;)
lamrz__ has quit [Quit: Leaving]
FDCX has quit [*.net *.split]
FDCX has joined #qi-hardware
<DocScrutinizer05>
sigh, another chip with embedded APE
<DocScrutinizer05>
it sounded so good
<DocScrutinizer05>
except for the OTA-management stuff, which I rather wanted to have disabled
<DocScrutinizer05>
ok, it got VoLTE, but how's about 3g/2G voice? Which bands will be supported?
<ysionneau>
talking about the Sequans bb+rf chip?
<DocScrutinizer05>
yup :-)
<ysionneau>
no 3g/2g at all
<ysionneau>
only 4g
<DocScrutinizer05>
oops
<ysionneau>
and only LTE actually
<ysionneau>
that's the downside :)
<DocScrutinizer05>
well, there's a reason why it's labeled "for IoT"
<ysionneau>
it's small, cheap, low power chip (don't ask me numbers, I don't have them, but it's our roadmap)
<DocScrutinizer05>
actually 3G/UMTS wouldn't even be compatible with the low-power claim
<DocScrutinizer05>
and iirc 3G royalties are insane
<ysionneau>
Which bands will be supported? < I don't know the entire list out of my head, I heavily tested band 13 so far
<ysionneau>
I know there has been some tests on band 4
<astr>
Recommendations for a tiny/mini/small speaker + amp that is as loud as the one in the nano note or louder? bonus points for even better sound quality :)
<astr>
this is for a diy handheld computer with a 4.3inch lcd to give you a idea of the size of what the speaker is going into
rz2k has quit []
jekhor has quit [Ping timeout: 264 seconds]
wej has quit [Read error: Connection reset by peer]
wej has joined #qi-hardware
<DocScrutinizer05>
that's a tricky question
<DocScrutinizer05>
generally you won't get away without some sort of resonance chamber or transmission line
<DocScrutinizer05>
unless you use speaker of at least ~5cm diameter
<DocScrutinizer05>
and even that one will sound mickey mouse when operated without any proper chanber/damping etc
<DocScrutinizer05>
general problem: the basic speaker has a front and a backside ;-) sounds trivial bit that's actually the problem you need to fix, since for acoustic waves of wavelength ~radius of speaker and longer, you get a short between front and back
<DocScrutinizer05>
so no matter how much energy you blast into your timy speaker and how far the tiny membrane goes forth and back - at 50Hz or 100Hz it just will mix the air and not produce any sound wave
<DocScrutinizer05>
the air goes straight around the speaker from front to back
<DocScrutinizer05>
you could power a 1cm speaker with 100W and it would only heat up the air
<DocScrutinizer05>
at 50Hz
<DocScrutinizer05>
you probably wouldn't hear anything in a meter distance
<DocScrutinizer05>
so you need a chamber at one of both sides, to contain the air in it and not allow it to just move around the membrane from front to back and vice versa
<DocScrutinizer05>
either you use a closed chamber, or an open one which basically is a transmission line then
<DocScrutinizer05>
and that chamber must get tuned to the speaker's properties, like inertia and damping of the membrane
<DocScrutinizer05>
otherwise you build a organ pipe
<DocScrutinizer05>
that only works for one frequecy, but then works extremely good on that single one
<DocScrutinizer05>
astr: sometimes you can find so called "closed speakers", they already have a chamber integrated, and on a good seller you can find datasheets that explain how to mount the speaker so it will sound good
<DocScrutinizer05>
but often they only mention frequency range, Wattage, resoncance frequency and Q of the speaker transducer, and leave it up to you to calculate a matching chamber for that
<astr>
DocScrutinizer05: thanks, very helpfull
<DocScrutinizer05>
sarcasm?
<DocScrutinizer05>
sorry! it's as nasty as that
<astr>
bouns points awarded
<astr>
no sorry chinaise way of writing has worn on me. I meant it in a good way
<DocScrutinizer05>
:-)
<astr>
too much reading of aliexpress english
<DocScrutinizer05>
make sure your chamber is not as perforated and soft material as the white silly thing in GTA01/02 ;-)
<astr>
can you get effenant little speakers that use 1W or less? but still as loud?
<astr>
s/effenant/efficient/g
<qi-bot>
astr meant: "can you get efficient little speakers that use 1W or less? but still as loud?"
<DocScrutinizer05>
umm, yup, I think 1W is feasible
<astr>
oh goody good, where? I guess not aliexpress hehe
<DocScrutinizer05>
I don't know where to buy small speakers
<DocScrutinizer05>
I either used spare parts for an existing design or talked directly to the manufacturer
<DocScrutinizer05>
for stuff like GTA03 speakers
<astr>
I haven't found any useful results for closed speakers
<astr>
I'm using ixquick.com
<astr>
ok
<DocScrutinizer05>
yeah, they are not exactly common in sub-inch size
<DocScrutinizer05>
I mean, such chamber *always* is bulky, that's by physical principles
kilae has quit [Quit: ChatZilla 0.9.90.1 [Firefox 29.0.1/20140506152807]]
<astr>
I think I can work with a 5cm one, though I don't know how big the chamber needs to be. I expect my diy handheld to be bulky
<DocScrutinizer05>
ooh, 5cm is already a great size
<astr>
bukly any way ... so what harm is a fre more cm for a speaker :P
<astr>
s/fre/few/g
<qi-bot>
astr meant: "bukly any way ... so what harm is a few more cm for a speaker :P"
<astr>
though I would prefer to keep the overall size small so I can still call it a handheld and hold it with one hand
<astr>
it's only for fun alarms, notifications, text2speech
<astr>
the speaker that is
<astr>
then again,I plan to have a pezio sounder = nice and loud for alarms to wake me up hehe mwhahah :D. not sure how to control one on the olimex LIME board
<DocScrutinizer05>
the horn is an acoustical transformer that creates a lot of air moving fast against low force, from a smal amount of air at driver moving slow at very high pressure/force
<DocScrutinizer05>
since only a small amount of air needs to get moved by speaker, you can use a small (but rigid strong) membrane
<DocScrutinizer05>
in a small case like phone, you don't use horns but chambers or transnissin lines 8usually a combination of both)
<astr>
DocScrutinizer05: I'll the my irc running. so feel free to dump and extra info,thoughts questions,links and I'll read them in the morning :)
<astr>
s/and/any/g
<qi-bot>
astr meant: "DocScrutinizer05: I'll the my irc running. so feel free to dump any extra info,thoughts questions,links any I'll read them in the morning :)"
<DocScrutinizer05>
nah, i'm also leaving now, cheers! :-9