[volt-nuts] Bits in ancient Panasonic phone

Andre Andre at Lanoe.net
Wed Feb 28 01:37:54 EST 2018


Hi, is there a guide anywhere on "good bits" to salvage from ancient Panabrickic (tm) GSM phones please?
I found one here, the display is fandango'd but other than that it did turn on very briefly with a "jump start" to its
circa 1998 NiCad pack.
I understand that there are often OCXO and other interesting bits, recall vaguely salvaging some of these from ancient
cell base station boards that got flooded out.
kind regards, -Andre
#include "CTC101.h"

________________________________________
From: volt-nuts <volt-nuts-bounces at febo.com> on behalf of Andre <Andre at Lanoe.net>
Sent: 28 February 2018 06:32
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] HP3458 ADC integrator (SPARES)

Can you make use of an LM3900? I have one here *somewhere*.
I think its a quad Norton, not sure how long its been there for.

also have a few canned op-amps etc
-Andre
________________________________________
From: volt-nuts <volt-nuts-bounces at febo.com> on behalf of Attila Kinali <attila at kinali.ch>
Sent: 27 February 2018 18:25
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] HP3458 ADC integrator

On Sat, 24 Feb 2018 12:59:21 +1300 (NZDT)
Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> 1) Reverse the supplies on U4 (in real circuit reversed supplies will fry the chip.)
> 2) Add 10k in series with reset switch
> 3) Swap connections to U4 inputs.
> 4) Use series shunt switch for reset switch as used in an actual 3458A.
> Once done together with swapping in LT1220 for LT1225 rest works as expected and output slews due to gate current of J1 and input bias current of U1

Ok, I played around a bit more and I think I now mostly understand what's
going on. The main problem was really the stability of the opamps chosen.
For the integrator to work, the added up gain and phase shift must still
fulfill the stability condition (obvious, yes, but.. well I am stupid at times)
I am not sure how the intermediate steps in a 3 opamp integrator work,
but I guess that should imediatly be obvious once a complete stability
analyis is done.

Thanks everyone who provided insight and feedback.

                        Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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