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Today's Topics:
1. Re: Opamp - somewhat off topic (Matt Dainty)
2. Re: Thoughts on WhatsApp? (Tim Wintle)
3. Re: Opamp - somewhat off topic (Andrew)
4. Re: Opamp - somewhat off topic (Peter Hemmings)
5. quad core blimey (Andrew)
6. Slony probs (Martin Moore)
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Message: 1
Date: Mon, 24 Feb 2014 09:02:12 -0500
From: Matt Dainty <matt@bodgit-n-scarper.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Opamp - somewhat off topic
Message-ID: <20140224140212.GR2245@simulant.bodgit-n-scarper.com>
Content-Type: text/plain; charset="us-ascii"
* Dave SMITH <Dave.Smith@st.com> [2014-02-24 08:50:44]:
> On 24/02/2014 14:25, Andrew wrote:
> > How do I define what I am looking for as the opamp itself, on ebay or
> > elsewhere. This is the bit I was getting really frustrated with - it
> > seems like a whole language defining these kinds of things.
>
> You just want a general-purpose OpAmp. I don't have any datasheets to
> hand so I'm not sure what to recommend I'm afraid. Many years ago, the
> standard would've been the 741, but that's been well and truly
> superceeded nowadays. When I've got a bit of time (I'm currently at
> work in a meeting), I'll do a bit more digging around to give you some
> suggestions.
>
> In reality, however, virtually any OpAmp you can buy will probably do
> what you want, as your requirements are not particularly taxing.
I was looking at a circuit for use with a Pi that featured an OpAmp and
that used a CA3140 part. I note in the features it's a replacement for
the 741 that Dave suggested.
HTH
Matt
--
"Phased plasma rifle in a forty-watt range?"
"Hey, just what you see, pal."
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Message: 2
Date: Mon, 24 Feb 2014 14:08:11 +0000
From: Tim Wintle <timwintle@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Thoughts on WhatsApp?
Message-ID: <1393250891.15643.8.camel@tim-desktop>
Content-Type: text/plain; charset="UTF-8"
On Sun, 2014-02-23 at 20:09 +0000, Mike Yates wrote:
> For those who haven't noticed, the price paid by Facebook for WhatsApp
> is the result of the latter's abuse of Android (and IOS)
> "Permissions".
I'm going to dispute that statement ..
All the big names aren't necessarily trying to grab cash out of mobiles
at the moment: They just want to be in a market-leading position to make
money out of stuff once that happens.
The money-centre of mobile hasn't been defined yet: it could be payments
(i.e. mobile payments with NFC are trying to take over from credit card
companies), it could be media rentals (e.g. Google Play), or it could be
something completely different.
i.e. Facebook were willing to pay that (frankly rediculous) price for
Whatsapp because they don't want another competitor in the field. Google
apparently bid the price up that far: presumably because they want
hangouts to be *the* way that people communicate in a post-sms and
standard phone call world.
Twitter is still afloat for the same reason: having the eyeballs *might*
lead to some way to make money in the future, even though there's no
prospect right at the moment.
I.e. the value is about owning the user's experience: not about the
contacts. I honestly think the fact your phonebook gets uploaded to
whatsapp is due to no more than dumb systems design.
Tim
------------------------------
Message: 3
Date: Mon, 24 Feb 2014 14:12:19 +0000
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Opamp - somewhat off topic
Message-ID: <530B5343.9080000@1dtv.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 24/02/14 14:02, Matt Dainty wrote:
> * Dave SMITH <Dave.Smith@st.com> [2014-02-24 08:50:44]:
>> On 24/02/2014 14:25, Andrew wrote:
>>> How do I define what I am looking for as the opamp itself, on ebay or
>>> elsewhere. This is the bit I was getting really frustrated with - it
>>> seems like a whole language defining these kinds of things.
>> You just want a general-purpose OpAmp. I don't have any datasheets to
>> hand so I'm not sure what to recommend I'm afraid. Many years ago, the
>> standard would've been the 741, but that's been well and truly
>> superceeded nowadays. When I've got a bit of time (I'm currently at
>> work in a meeting), I'll do a bit more digging around to give you some
>> suggestions.
>>
>> In reality, however, virtually any OpAmp you can buy will probably do
>> what you want, as your requirements are not particularly taxing.
> I was looking at a circuit for use with a Pi that featured an OpAmp and
> that used a CA3140 part. I note in the features it's a replacement for
> the 741 that Dave suggested.
>
> HTH
>
> Matt
Thank you Matt, a help indeed. And they are cheap and plentiful on Ebay.
Seems like the problem is solved.
Andrew
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Message: 4
Date: Mon, 24 Feb 2014 14:16:20 +0000
From: Peter Hemmings <peter@hemmings.eclipse.co.uk>
To: andrew@1dtv.com, Bristol and Bath Linux User Group
<bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Opamp - somewhat off topic
Message-ID: <530B5434.3090409@hemmings.eclipse.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 24/02/14 13:25, Andrew wrote:
> On 24/02/14 13:13, Dave SMITH wrote:
>> On 24/02/2014 13:46, Andrew wrote:
>>> ps I forgot to mention that I have done a load of googling but I am not
>>> coming up with anything I understand.
>> Have a look at the "closed loop, non-inverting" section of the OpAmp
>> page on Wikipedia. There's a circuit diagram showing how you connect up
>> an OpAmp with two resistors to define the gain you want.
>>
> Thanks Dave. That looks really simple.
>
> How do I define what I am looking for as the opamp itself, on ebay or
> elsewhere. This is the bit I was getting really frustrated with - it
> seems like a whole language defining these kinds of things.
Sorry for butting in Dave,
"Core blimey" (London Accent) I never thought these still existed! I
remember them from many years ago (more the 40!).
Generally if you are designating a circuit you should have an idea of
what you want regards supply voltage and type of encapsulation etc. If
you are makin a high gain amp you may have to remove any offset voltage
or buy an amp that can compensate for it. Bandwidth also varies with
feedback (as I recall) but should not be a problem with your use.
When these came out, they revolutionized the electronics industry as
they could be used in so many different ways and were so cheap (ah those
were the days).
PS just saw other posts, there are a lot more on this list with newer
knowledge on OpAmps than me, good luck.
(goes back to armchair to relax in the knowledge that some thing learnt
many years ago are still extant!)
> Andrew
>
>
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol
>
--
Peter H
------------------------------
Message: 5
Date: Mon, 24 Feb 2014 14:43:53 +0000
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: [bristol] quad core blimey
Message-ID: <530B5AA9.3020009@1dtv.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 24/02/14 14:16, Peter Hemmings wrote:
> "Core blimey" (London Accent) I never thought these still existed! I
> remember them from many years ago (more the 40!).
Things certainly change. It used to be Cor blimey. I presume you are on
the new quad core blimey!
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Message: 6
Date: Mon, 24 Feb 2014 15:17:36 -0000
From: "Martin Moore" <martinm@it-helps.co.uk>
To: "'Bristol and Bath Linux User Group'" <bristol@mailman.lug.org.uk>
Subject: [bristol] Slony probs
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAFLxZtQqo65Oo+1jhlUB9DvCgAAAEAAAALlZF0q9paZLhHF4LtCdbT0BAAAAAA==@it-helps.co.uk>
Content-Type: text/plain; charset="us-ascii"
I've restored a postgres 8.4 database onto a 9.3 installation (on Debian
Jessie).
Running a script (as used in 8.4 so may need to be changed, but can't find
anything) which contains the following
define CLUSTER T1;
define PRIMARY 1;
define SLAVE 10;
cluster name = @CLUSTER;
define origin1 origin = @PRIMARY;
define origin2 origin = @SLAVE;
define primary id = @PRIMARY;
define slave id = @SLAVE;
define set_user_admin id = 10001;
node @PRIMARY admin conninfo = 'dbname=myname host=localhost user=slony';
node @SLAVE admin conninfo = 'dbname=myname host=slave.host.com user=slony';
create set (id = 10001, @origin1, comment = 'user_admin');
set add table (set @set_user_admin, @origin1, id = 10002, full qualified
name = 'public.users', comment = 'Table public.users');
fails as below.
./addsst.slonik:3: WARNING: Auto-casting int to text: 10001
CONTEXT: PL/pgSQL function "_T1".storeset(integer,text) line 11 at RETURN
./addsst.slonik:3: WARNING: Auto-casting int to text: 1
CONTEXT: PL/pgSQL function "_T1".storeset(integer,text) line 11 at RETURN
./addsst.slonik:4: WARNING: Auto-casting int to text: 10002
CONTEXT: PL/pgSQL function "_T1".altertableaddtriggers(integer) line 53 at
EXECUTE statement
SQL statement "SELECT "_T1".alterTableAddTriggers(p_tab_id)"
PL/pgSQL function "_T1".setaddtable_int(integer,integer,text,name,text) line
99 at PERFORM
SQL statement "SELECT "_T1".setAddTable_int(p_set_id, p_tab_id, p_fqname,
p_tab_idxname, p_tab_comment)"
PL/pgSQL function "_T1".setaddtable(integer,integer,text,name,text) line 28
at PERFORM
./addsst.slonik:4: PGRES_FATAL_ERROR lock table "_T1".sl_config_lock;select
"_T1".setAddTable(10001, 10002, 'public.users', 'users_pkey', 'Table
public.users'); - ERROR: operator is not unique: text || integer
LINE 3: '"_T1".log_truncate(' || i_tabid || ');'
^
HINT: Could not choose a best candidate operator. You might need to add
explicit type casts.
QUERY: SELECT 'create trigger "_T1_truncatetrigger" ' ||
' before truncate on ' || i_fqtable || ' for
each statement execute procedure ' ||
'"_T1".log_truncate(' || i_tabid || ');'
CONTEXT: PL/pgSQL function "_T1".altertableaddtruncatetrigger(text,integer)
line 3 at EXECUTE statement
SQL statement "SELECT "_T1".alterTableAddTruncateTrigger(v_tab_fqname,
p_tab_id)"
PL/pgSQL function "_T1".altertableaddtriggers(integer) line 65 at PERFORM
SQL statement "SELECT "_T1".alterTableAddTriggers(p_tab_id)"
PL/pgSQL function "_T1".setaddtable_int(integer,integer,text,name,text) line
99 at PERFORM
SQL statement "SELECT "_T1".setAddTable_int(p_set_id, p_tab_id, p_fqname,
p_tab_idxname, p_tab_comment)"
PL/pgSQL function "_T1".setaddtable(integer,integer,text,name,text) line 28
at PERFORM
Any ideas? Or even a slony/postgres forum that is lively!
Martin
------------------------------
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