audio recording on IC -help wanted

[Homer J Simpson]

"Jim Thompson" <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote in
message news:n8rul2ltukihlq55073rhnpch1gd1roh9n@4ax.com...

On those sites where I might want to hear from them, I assign them a
site-specific E-mail address... their.name@my.address.forward.com

How about SatansMinion@TheGatesTo.Hell

(Say it aloud).

 

[Chris Jones]

Joerg wrote:

miso@sushi.com wrote:

Joerg wrote:

Hello All,

Disclaimer: I don't often work with laser diodes. So please try to
restrict the number of "Duh!" statements to 2-3 per post

After perusing the offerings of the usual contenders such as AD, TI, LTC
I am wondering whether there is a better solution to drive a >120mA
laser diode. Sure, the ADN2830 can do that but burning off a lot of
dissipation in those tiny 5mm LFCSP packages gives me the goose pimples.
ONET and most comms drivers seem to be too wimpy at 100mA or less.

We need to control the current from our circuitry but not at more than a
few hundred Hz rate for swings between 90%-100%. It's going to be a loop
so linearity of the control mechanism isn't too important. Noise is
critical though.

Are there larger and widely available laser driver chips? Maybe in SO
packages?

Of course, my dream would be to have the TEC controller right in there
with it. Don't know why that's not done yet but one has to have dreams.
The ADN8831 looks alright for TEC except for the fact that it does PWM
and that could interfere with our low noise application. Comes with an
eval board which is nice. If anyone knows a better TEC controller, maybe
with the bridge FETs already in there, please let me know. If it doesn't
contain its own PID loop we could probably live with that.

--
Regards, Joerg

http://www.analogconsultants.com


You could do a test board and measure the theta JA with the part
soldered in place. I may be reading more into the datasheet than
intended, but they mention the exposed paddle. I assume the
manufacturer wants a patch of copper on the PCB to attach to the
paddle? In addition, some heat leaves from the bond wires. The capacity
is proportional to the square of the wire diameter, so often in these
kinds of chips they spec a fatter than required bond wire. It may be
possible to put a patch of copper on the PCB that connects to the power
pins to improve the theta JA.


Those fancy new "thermally effective" packages often do require some
heat to be conducted into a copper pour plane. The chips I have seen
this way were within temp specs but way too hot for my taste.

Well, if there is no alternative to the ADN2830 there is always the
method of using two in parallel, setting each to half the current. They
are just kind of expensive for a controlled current source. North of $10
a pop. If this all goes into a larger production run it'll have to
become discrete but we are far away from that point.

I think the LFCSP packages with the exposed paddle should be soldered to a
square of metal which is connected to the ground plane by lots of vias. It
is important that the paddle is really soldered properly. When soldering
them by hand, I put some flux on the paddle of the IC and then tack down
some pins of the device before soldering the ground connection from the
back side of the PCB. I feed solder down one via and make sure it comes up
the other vias, that way I can be pretty sure it has wetted the IC package.
Other people do it in different ways and the assembly contractors seem to
have no trouble with them, I think they use solder paste. The thermal
resistance in the package would be pretty low because the paddle is just a
square of solid copper with the die attached to one side and the PCB
soldered to the other side. (or at least that applies to the ones that I
have seen, though those were not really high-power devices.)

Chris

 

[PolyVinalDistillate]

I have thrown together a little decoder for the sensor to give me
left/right pulses at minimum spacing possible. This has given me an
accuracy of 600 devisions-per-inch (approx. 1/24 mm). The kind of
number I'd have expected if I thought about it for any length of time


I think that's all there is to say about this little device now, except
mebbe 'I want more of them' Thanks for all the motivation to stop me
being a lazy arse, and actually bother to figure it out! I'm awfully
pleased - it's just the thing I wanted for a CAD Milling machine. Now I
just have to build the milling machine... heh

 

[Lostgallifreyan]

"PolyVinalDistillate" <PolyVinalDistillate@yahoo.co.uk> wrote in
news:1163896534.112611.224590@m7g2000cwm.googlegroups.com:

Thanks for all the motivation to stop me
being a lazy arse, and actually bother to figure it out!

It keeps me going too. Got to draw on anything I can to motivate me, on
some things... I'm trying to re-aqquaint myself with some trigonometry to
rotate an array of points. Interesting distractions are as helpful as
trying to focus, and definitely more fun.

 

[Joerg]

Hello Rene,

BTW, an analog input instead or in addition to the potentiometer
would be nice. That's why we can't use our fancy one in the fancy
box. Unless I butcher it. If you want to try etalon hopping and
stuff like that you need to have an analog input.

The input is analog, sampled. Radiometric between the
the suuply rails.

Current-summing into the thermistor node? That would work. But a
separate input would be nice. Doesn't have to be a low offset opamp, a
quarter of a LM324 would do because it would typically be in a
regulator loop.


Actually, the NTC's have their own inputs, even their own ADC.
The pot has an input of its own at the cpu internal ADC.

That would be a good spot to connect the external prototype circuitry
to. A tie into the thermistor node is always a white knuckle ride. If it
shorts for some reason the TEC might attempt to create a new ice age or
a smelter, depending on which way it goes because the uC would have no
way of knowing what happened.

--
Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Rene,

We just have to be careful and get the A type. The first page says 1%
tolerance which sounds good as long as the note in the brackets isn't
overlooked. Further down where the real meat is the spec says 1.20V to
1.30V for the non-A. That computes to 8% or +/-4% which can be a bit
of a white knuckle ride if you want to run an LD close to the edge.

Of course, one can always add a "throttling circuit" that begins to
rob Vsense current when the monitor diode reaches the spec limit for
laser power.


Just in case the LM317 is too close to the lower rail, you can always
have a series resistor together with the laserdiode.

Usually it's not too close because the LD drops a good 2V so you could
even use a BJT to control the Vsense node. Just in case the five cents
for a BSS123 are too much money ;-)

One challenge that is left is to monitor the LD current. That would
require a diff amp structure and a wee series resistor. Often MPD level
monitoring will be enough though.

--
Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Lostgallifreyan wrote:

Rene Tschaggelar <none@none.net> wrote in news:45603a99_3@news.bluewin.ch:


Just in case the LM317 is too close to the lower rail, you can always
have a series resistor together with the laserdiode.




I don't understand this. If it was a voltage regulation, it would arguably
be too far, needing a negative on the sense pin to get it down to zero, it
couldn't get 'too low' otherwise. All of which means nothing because it's
current, not voltage, that must be controlled.

IIUC you'd still have almost a volt from Vsense (ADJ) to GND. Enough to
hang a transistor to rob some current.

I actually do use a resistor in series in my drivers, I forgot to mention
it here, not sure why. I use a 1 or 2 ohm series resistor before the
parallel caps across the diode, to make them filter out spikes more easily.

If you had one between cap and LD you could modulate

--
Regards, Joerg

http://www.analogconsultants.com

 

[Homer J Simpson]

"Lostgallifreyan" <no-one@nowhere.net> wrote in message
news:Xns9880B5ABDF662zoodlewurdle@140.99.99.130...

And the so-called Deathstar drives. In which case, the obituaries are
fortunately premature. They never let me down. I never had the known bad
ones though.

"What holds 10 Mb of data or a pint of sea water? An IBM hard drive!"

(Someone exchanged them for good ones and dumped the duds as a reef).

 

[Ross Herbert]

On Thu, 16 Nov 2006 21:45:56 -0800, Winston <Winston@BigBrother.net>
wrote:

Ross Herbert wrote:

Winston,

I have been trying to locate those part numbers on the Tyco website
without any joy.

The closest I can find are;
http://catalog.tycoelectronics.com/TE/bin/TE.Connect?S=23810&P=88074,2383,76450&M=PPROP&BML=10576,16358,17560,17540,17739&LG=1&I=13&N=1&IDS=60047
and
http://catalog.tycoelectronics.com/TE/bin/TE.Connect?S=23810&P=88074,2383,76450&M=PPROP&BML=10576,16358,17560,17540,17739&LG=1&I=13&N=1&IDS=76937

Are these the items you require? These part no's don't have the '5'
after the leading 1- as in your specification. It might make a
difference....

That's them, Ross.

Tyco changed their part numbering system recently to include a leading
'5', but parts without the leading '5', in this case, are the same as
those with the '5'.

Thanks!

--Winston

Winston,

I see your problem... they are not readily available - anywhere that I
can find anyway! Unless some large OEM has some over from a production
run (difficult to imagine for such a specialised use product such as
this) then you are stuck with having to order MOQ and wait.
Unfortunately, if you are building for a customer, he is likely to
baulk at having to pay for the unused portion of the stock indent -
and if you don't charge him then you will be stuck with something you
may not use in the future.

Good luck.

 

[Ed]

daltonmcl@yahoo.com wrote:

I am proposing that we put some of our electronics knowledge to some
practical uses.
For example; making simple fuel cut defenders

Often horrid voltage clamp devices - nasty. (I map cars and I tell
people to remove these things)

, logic probes, boost

controllers etc.

I would personally like some one to help me with a simple radar
detector circuit.

 

[Eeyore]

googlealerts@mindmodule.com wrote:

Hi,

I am looking for a source of tiny (e.g. 2mm x 1mm x 1mm) surface mount
leds that blink.

I know that circuits can be constructed for this purpose but I assume
that if you can buy larger bulb type leds that flash that the work may
already have been done and miniaturized for a surface mount product.

The flash length and dwell time is not really important to the purpose.

Thanks for any leads

Kingbright ?

Graham

 

Thanks for the lead Graham but unfortunately they don't make them
either.




Eeyore wrote:

googlealerts@mindmodule.com wrote:

Hi,

I am looking for a source of tiny (e.g. 2mm x 1mm x 1mm) surface mount
leds that blink.

I know that circuits can be constructed for this purpose but I assume
that if you can buy larger bulb type leds that flash that the work may
already have been done and miniaturized for a surface mount product.

The flash length and dwell time is not really important to the purpose.

Thanks for any leads

Kingbright ?

Graham

 

[Lostgallifreyan]

"colin" <no.spam.for.me@ntlworld.com> wrote in
news:87geh.2623$z01.1894@newsfe3-gui.ntli.net:

Now I just need a way to avoid making an EL driver transformer with
thousands of turns.

Would a trigger transformer for a xenon tube work for that? (I haven't
thought this through, the idea just came to me so I put it forward as it
is).

 

[Don McKenzie]

colin wrote:

Well thankfully I got it working a lot better now, thanks to poly' who
sugested the negative contrast voltage wich was indeed the case,
I just fed it -vee through a 1M then 100kR to be safe and it displayed ok.

Out of interest, what -vee level did you need to use?

Don...


--
Don McKenzie
E-Mail Contact Page: http://www.dontronics.com/e-mail.html

Crystal clear, super bright OLED LCD (128x128) for your microcontroller.
Simple serial RX/TX interface. Many memory sizes.
http://www.dontronics-shop.com/product.php?productid=16460

 

[Mike Harrison]

On Wed, 13 Dec 2006 14:37:48 GMT, "colin" <no.spam.for.me@ntlworld.com> wrote:

Hi,
Im looking for a MCU with enough internal ram to bitmap a 1/4vga LCD
screen
wich is 9600 bytes at least for 1 layer of mono,
most ive looked at so far seem to stop short of this,
from microchip the dspic30f6010 has 8k internal ram
im using the dspic30f4011 atm which has about half that,
and now the tables ive been looking at farnell seem to have totaly incorect
amounts of ram listed,

any one got any pointers to tables or a device theyve used for such a thing
?
or is it possible to somehow compress the bitmap ?
I know I could use an external ram but this isnt very attractive.

I gues a lcd controller might do too, but it would be usefull to have a mcu
to do some other mcu type stuff with.
mostly for debug info for my motor controller but I was thinking of a simple
curve tracer for inductors to find the saturation point
maybe even a bode plot to find resonant freq etc.

Colin =^.^=

Philips/NXP LPC2104/5/6

 

Alex wrote:

I have a portable flash-memory recorder which has a mic input.

The input socket has "Plug-In-Power" this provides power to run a
suitably-designed unpowered electret mic which is plugged into the
socket.

If I use one of the older-style electret mics which contains a
battery for its own power then would that severely overload the input
electronics of the flash recorder?

I'm presuming we're talking about a jack plug & socket here? Mono or
stereo? The jack plug has a tip and rings for the audio and DC power?
Maybe insertion of an unsuitable plug eg the one on your battery
powered mic might short the DC? Anything in the instructions/user
notes/online manual about that?

I wouldn't think that the signal level itself would cause damage. I
have used an 1980s Tandy stereo mike (with an new AA cell in the
barrel) with a PC sound card and I had to crank the input gain right up
compared with the cheapo (unpowered) mike in my webcam, not that that
proves anything much

Maybe a Google is order for a more specialised forum?

 

mike.j.har...@gmail.com wrote:

I looked belatedly at your link. I don't think you'll be damaging
anything.

 

[Eeyore]

Lostgallifreyan wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote
Phildo wrote:

http://groups.google.co.uk/group/alt.audio.pro.live-sound/browse_threa
d/thread/44b297b5646e4655/07ad85e7ac4fb61a?hl=en#07ad85e7ac4fb61a

Read em and weep.

From the above link.......

" http://i10.tinypic.com/2zfsff8.jpg
http://i7.tinypic.com/4htbcbp.jpg
http://i15.tinypic.com/29bgglt.jpg
http://i15.tinypic.com/40ljq53.jpg
http://i15.tinypic.com/44rdbuv.jpg
http://i15.tinypic.com/2nbepw9.jpg

Proof QSC is using single sided phenolic paper PCBs.

Phildo "

The poster 'Phildo' a sound mixing engineer who mixes sound on cruise
liners and posts in alt.audio.pro.live-sound is apparently under the
impression that one of the products above contains phenolic-paper
pcbs.

Apparently my word that it's not isn't good enough for him.

Comments welcome.


I've seen stuff like that, it seems to be made the same way, by a resin and
fibrous material rather than a woven cloth. It's still an epoxy resin
though, the stuff I saw was more like a ceramic for hardness than SRBP
could ever be. It even chipped like a ceramic at the edges. I don't know
what it is, exactly, but it seems to be a way to use the SRBP-type process
with materials that are as tough as glass fibre/epoxy boards when the board
is finished. I think they're as hard, but more brittle.

I've known it as 'composite' material. I first used it in 1980. You can get it
in white as well as blue. You might be surpised just how flexible it is
actually. Phenolic's much more brittle.

Subsequently I've discovered it's called CEM1.

Your assessment's correct too. That is indeed how it's used. It even may be
punchable.
However this guy Phildo has got it into his head that it's phenolic.

Graham

 

[Daniel Mandic]

Eeyore wrote:

The usual Yank revisionism. Or is it simply bad education ?

Right Right, or Left to Right.

The USAAF wasn't significantly involved in any defensive operations.

Now when you say.... hmmm, I also cannot remember any.

The RAF had defeated the Luftwaffe's attempt to gain air superiority
over Britain about 18 months before USAAF aircraft even arrived in
the UK. Even if they'd failed, an attempt at an invasion would never
have got past the Royal Navy.

Right.

Even with US aircraft to help bomb targets in occupied Europe, the
RAF's bomber command vastly exceeded the tonnage of bombs dropped by
American crews.

Why have the American bombed at all? England I can understand...

Graham

Kind regards,

Daniel Mandic

 

[Boris Mohar]

On Fri, 29 Dec 2006 11:59:15 -0800, DaveC <me@privacy.net> wrote:

Big can-type electrolytics: 1800-2200uF, 400-plus wv, screw terminals.
Limitation is height: 3.5 inch max (not including terminals).

(OE p/n: Nichicon LNR2G182ASMXMG from old caps).

Mouser, DigiKey, Allied have nothing. All others I can find are non-stock,
min order.

I want 3.

Give http://www.capacitorsplus.com/ a call. Their website sucks but service
is great.

--

Boris Mohar



--
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