Date   
Re: OT: I/V curve tracing made easy with Python and PyVISA

Tony Fleming
 

Jim (or anyone out there) can answer my question. I have Tektronix 2465 DMS
and I just purchased PC6407 RQus1, but I never used anything like this
before.
Is there some instructional video that would show how to use it and Python
combination?
I'm learning Micro-Python on my Arduino and ESP8266/ESP32 boards - I love
Python!!!
Here is the video I'm learning from:
https://www.youtube.com/watch?v=rfscVS0vtbw&t=3773s

On Thu, May 16, 2019 at 11:06 AM Jim Ford <james.ford@...> wrote:

Thanks, Magnus, for posting. I, too, am interested in automating my test
bench using Python. This after seeing the nightmare at work of piles of
Labview code tweaked by many engineers over several decades. You know
there's a problem when tests have to pass 2 out of 3 times because of race
conditions and other nasties in the code! We asked one of the software
jocks for an Abort Test button that actually gets out of a test, but he
said "Well, it's not that simple. Which module should it jump out of, and
where should it land?" Uh, never mind...!With the VISA wrappers it
*should* be easy to write test code for both my old (mostly HP) instruments
with their GPIB interfaces and newer gear with USB. Hoping to get a GPIB
card for my garage lab computer and get programming in Python over the
summer (of which year remains to be seen!)Jim Ford Sent from my Verizon,
Samsung Galaxy smartphone
-------- Original message --------From: "magnustoelle via Groups.Io"
<magnustoelle=yahoo.com@groups.io> Date: 5/16/19 8:26 AM (GMT-08:00)
To: TekScopes@groups.io Subject: [TekScopes] OT: I/V curve tracing made
easy with Python and PyVISA Good Day to the group,this is completely
off-topic, but as several of you seemed always interested in curve-tracing
applications, let me share my excitement with you...I know that I am very
late into this, but allow me to say that I have found the use of the Python
scripting language in combination with libraries & packages such as PyVISA
very powerful.To cut a long story short: I was curious to see, if I can
replace my NI LabView projects with something simpler, less costly and more
portable between Operating Systems such as Windows, Linux etc. And after
playing with Python for a few days, it seems that Python offers such an
alternative.I still like how easy it is to generate appealing GUIs with
LabView, but even when using hierarchical designs, LabView "code" can be
hard to read and comprehend - just try to decipher your own VIs after a few
months!I have used PyVISA https://pyvisa.readthedocs.io/en/master/ for
easy communication with T&M equipment and libraries such as mathlibplot
https://matplotlib.org/ for plotting and numpy https://www.numpy.org/ for
a few math operations. The documentation and tools come for free, and there
are tons and tons of on-line training courses on Python as well as code
examples etc. which are available at 0 costs.Curve-tracing application:I
have used a GRUNDIG/digimess PN300 programmable power supply & a common NI
USB-GPIB adapter; then created some simple Python-scripts which allow the
I/V-curve tracing of two-terminal devices such as diodes and of
three-terminal devices such as transistors. For the latter, output A from
the power supply provided the Collector-Emitter sweep voltage, and output B
and a 22kOhm resistor provided the base current sweep.I have never really
had any formal education in programming/coding, but I have found it fairly
easy to create the attached PNG diagram, to save the current and voltage
data to a local file for post-processing with MS Excel etc.While this is
nothing to "write home about" - my heartful recommendation is: If you have
the interest and leisure, give Python and a stab into PyVISA a try!I am
including my simple Python code below . I am sure there are many things
which could be improved - however, please let's do not discuss
here...Cheers,MagnusP.S. I am aware that the GRUNDIG PN300 power supply is
not a precision instrument, but I have chosen it for simplicity - upgrading
to precision DMMs and more precise current/voltage sources and the like
would be easy.# Setup Digimess/GRUNDIG PN300 power supply# Testing
three-terminal electronic devices such as transistors# Set-up for
independent operation, Voltage and Currents for output A and readback
Current measurements# Set-up Voltage and Currents for output B and readback
Current measurements and turn off outputs# Hardware setup: Connect emitter
to common GND, collector to pos. terminal output A, connect base to output
B using a 22k series resistor for base currents.# Magnus Tölle, last edit:
13th May 2019# Setup: Easyinstall from
https://pypi.org/project/setuptools/0.6c11/#files first, and "easyinstall
pip" second# Install Python, pip, matplotlib, numpy, pandas, seaborn and NI
VISA from ni.com# References:
https://github.com/demisjohn/Keithley-I-V-Sweep/blob/master/Keithley%20I-V%20Sweep%20v2.py
# Import libraries for plottingimport matplotlib.pyplot as pltimport numpy
as np# import pandas as pd# import seaborn as sns# Import libraries for
VISA controlimport visa# Optional logging of PyVISA# visa.log_to_screen()#
Import other librariesimport time # as to allow pause between
measurementsimport csv # as to allow saving data file# For UTF Coding to
avoid encoding issues:# -*- coding: utf-8 -*-# Program runs on Windows
only:import sysimport os # Filesystem manipulation# Disable printdef
blockPrint(): sys.stdout = open(os.devnull, 'w')# Restore printdef
enablePrint(): sys.stdout = sys.__stdout__def windows_interaction():
assert ('win' in sys.platform), "This program only runs on Windows
systems." try: windows_interaction() except AssertionError as
error: print(error) print('This script was not executed')#
open resource Digimess/GRUNDIG PN300 power supplyrm =
visa.ResourceManager()# rm.list_resources()res = rm.list_resources()print
("Please connect and power-up GPIB adapter and PN300 power supply")print
("Please configure PN300 for GPIB and note address - default is address
7")PN300_GPIB_address = input("Please enter GPIB address:")print ("Please
connect DUT as follows:")print ("Emitter to common GND, collector to pos.
terminal output A, connect base to output B using a 22k series
resistor")print("Found the following equipment / resources:")print(res)
# print("Opening " + res[-1])PN300 = rm.get_instrument ('GPIB::' +
str(PN300_GPIB_address)) # Query to confirm that Digimess/GRUNDIG PN300 is
presentprint (PN300.query('*IDN?')) # Initialize and setup
Digimess/GRUNDIG PN300 power supply for constant voltage, independent
operationPN300.write('*RST')PN300.write('OPER_IND')PN300.write('CONT_CV')#
Ask user for voltage setup, current limits for output AVstartA =
input("Enter min. voltage sweep setting for output A in Volt: ")VstopA =
input("Enter max. voltage sweep setting for output A in Volt: ")VstepA =
input("Enter number of sweep steps for output A: ")VoltsA =
np.linspace(int(VstartA),int(VstopA),(int(VstepA)+1))Current_setA =
input("Enter current limit for output A in Ampere: ")Current_setA = 'ISET '
+ Current_setA# Ask user for voltage setup, current limits for output
BVstartB = input("Enter min. current sweep setting for output B in µA:
")VstopB = input("Enter max. current sweep setting for output B in µA (max.
1300µA): ")VstepB = input("Enter number of sweep steps for output B:
")Current_setB = input("Enter current limit for output B in Ampere:
")Current_setB = 'ISET ' + Current_setB# Ask user for base current resistor
valueResistor = input("Enter measured series resistor value in kOhm:
")Resistor = float(Resistor)*1E3VoltsB =
np.linspace(float(float(VstartB)*1E-6*Resistor),float(float(VstopB)*1E-6*Resistor),int(VstepB)+1)
# Ask user for DUT nameDUTname = input("Enter name of the device under test
or DUT: ")# Set timeout to 10 secondsPN300.timeout = 10000# Enable outputs,
and set output A and B to 0V, inform user that measurements start
nowPN300.write('SEL_A')PN300.write('VSET
0.00')PN300.write(Current_setA)PN300.write('SEL_B')PN300.write('VSET
0.00')PN300.write(Current_setB)PN300.write('OUT_ON')print("Starting with
measurements now")VoltageDataA = []CurrentDataA = []CurrentDataB = []for
Voltage2 in VoltsB: PN300.write('SEL_B') PN300.write('VSET
'+(str(Voltage2))) Voltage2A = PN300.query('VOUT?')
Voltage_formatted2A = float(Voltage2A[2:7])
CurrentDataB.append(Voltage_formatted2A/Resistor) for Voltage1 in
VoltsA: PN300.write('SEL_A') PN300.write('VSET
'+(str(Voltage1))) Voltage1A = PN300.query('VOUT?')
Voltage_formatted1A = float(Voltage1A[2:7])
VoltageDataA.append(Voltage_formatted1A) # time.sleep(0.1) optional
delay time of 0.1 seconds Current1A = PN300.query('IOUT?')
Current_formatted1A = float(Current1A[2:7])
CurrentDataA.append(Current_formatted1A) print ("Emitter voltage
and current: ", Voltage1A, Current1A) print ("Base current in µA:
", (Voltage_formatted2A/Resistor*1E6))DataArrayA =
np.asarray((VoltageDataA, CurrentDataA, CurrentDataB)) # Set output A to
0V and turn outputs offPN300.write('OUT_OFF')Voltage_setA = 'VSET
0.00'PN300.write(Voltage_setA)# Notify userprint("Finished measurement and
outputs turned off")plt.style.use('seaborn-whitegrid')for IndexA in
range(0, int(VstepA)+1): IndexB = IndexA+1 IndexC =
IndexA+2plt.plot(VoltageDataA[(IndexA*int(VstepA)+IndexA):(IndexC*int(VstepA)+IndexC-1)],
CurrentDataA[(IndexA*int(VstepA)+IndexA):(IndexC*int(VstepA)+IndexC-1)],
linestyle='--', marker='x', markersize=8, color='g')plt.xlabel('Voltage in
Volt')plt.ylabel('Current in Ampere')plt.legend([DUTname + ' I/V curve'],
loc='best', shadow=True)plt.show()# Save the Data to a csv-file with the
DUT name# with appended rows for VoltageA, CurrentA, CurrentB dataNewFile =
open(DUTname+'.csv', 'w')with open(DUTname+'.csv', 'w', newline='') as fp:
wr = csv.writer(fp, dialect='excel') wr.writerow(VoltageDataA)with
open(DUTname+'.csv', 'a', newline='') as fp: wr = csv.writer(fp,
dialect='excel') wr.writerow(CurrentDataA)with open(DUTname+'.csv',
'a', newline='') as fp: wr = csv.writer(fp, dialect='excel')
wr.writerow(CurrentDataB)# Close the file - end of python
scriptNewFile.close()


Re: [OT] surface mount components

Chuck Harris
 

If you use a glue, you must make sure that it doesn't
end up on the solder pads.

I don't know about you, but I cannot control crazy glue
that well.

Complicated boards get a tiny dot of epoxy dead center
in the footprint to hold the part down. These boards are
populated by robotic pick and place machines, and the
epoxy is placed there by that machine.

The solder paste is put on by wiping it over the holes
in a specially made etched solder paste mask.

Smaller less complicated boards often use the solder paste
to hold the parts down.

-Chuck Harris


Tony Fleming wrote:

Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Re: [OT] surface mount components

Glenn Little
 

Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
One method that works for me is a small C clamp. I put the part about
where I want it and clamp it lightly. Then I nudge it into the exact spot
and do the soldering. It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this. What also
may work is a dab of plastic acrylic cement. While it's liquid you can use
it to hold parts where you like. Then nudge a bit while it starts to set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering. Or just put it
off center and solder one side of the part; once you do that it will stay
in place while you do the other side.
For repairs it's usually enough to use residual solder. For fresh
installation you need to add some, of course. In the latter case, solder
the board before you install the part and then you can clean up any
bridges. Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers. They fustrate me too. Lately, I have to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.







--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: [OT] surface mount components

Bob Albert
 

I would only use glue if other methods seem inadequate.  It's a foreign material that may cause long term problems.  Not sure about that.  That's why I wouldn't use crazy glue or epoxy.  The latter is so tenacious that later repair may be difficult.  So acrylic cement seems to be a good choice.
Frankly, I prefer the clamp method.  It leaves no residue.  As for having the part orient itself, sometimes that doesn't work and you have a mess on your hands.  Heating all terminals simultaneously can be challenging also, requiring special tools and good dexterity.
I always worry about overheating the part.  So I try to work quickly without rushing so as to minimize thermal stress.
ChipQuik has some products that can be useful but their stuff isn't cheap.  I try to get along without it because I don't do these things often enough to justify having that around.
In the final analysis, my most useful tools are a fine tip soldering iron for installation and, for removal of devices with several pins, hot air.  I have removed complex ICs, relays, connectors, and more with hot air.  It gets difficult if the part is through hole and bent over on the solder side.  Sometimes I lose patience and break a part while removing it, thinking that surely it's hot enough.  But wasn't.  And my many years of experience making cold solder joints makes me careful during installations.
There is no substitute for practice and experience.  As the carpenter says, measure twice and cut once.  So don't assume anything, since each job has quirks.  A few moments of pondering how to do it is worth a lot.
Bob

On Thursday, May 16, 2019, 9:35:29 AM PDT, Glenn Little <glennmaillist@...> wrote:

Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably
are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used
will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage.  The issue is especially bad
with fragile leadless parts like SMD capacitors.  If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
  One method that works for me is a small C clamp.  I put the part about
where I want it and clamp it lightly.  Then I nudge it into the exact spot
and do the soldering.  It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this.  What also
may work is a dab of plastic acrylic cement.  While it's liquid you can use
it to hold parts where you like.  Then nudge a bit while it starts to set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering.  Or just put it
off center and solder one side of the part; once you do that it will stay
in place while you do the other side.
For repairs it's usually enough to use residual solder.  For fresh
installation you need to add some, of course.  In the latter case, solder
the board before you install the part and then you can clean up any
bridges.  Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
      On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
  On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers.  They fustrate me too.  Lately, I have to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.








--
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist  QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv@...    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM  NRA LM  SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: [OT] surface mount components

Tony Fleming
 

Thank you for more information about the Crazy Glue, vapors.... My friend
did this when he replaced couple SM parts. I'm sure if you used this an all
SMD's it would cause problem if soldered in a oven.

I'll look for the glue - quick search on Google :
https://www.hisco.com/Catalog/Adhesives-Sealants-Tapes/Adhesives/Epoxy-Adhesives/114004-1998


On Thu, May 16, 2019 at 11:35 AM Glenn Little <glennmaillist@...>
wrote:

Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably
are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used
will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
One method that works for me is a small C clamp. I put the part
about
where I want it and clamp it lightly. Then I nudge it into the exact
spot
and do the soldering. It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this. What also
may work is a dab of plastic acrylic cement. While it's liquid you can
use
it to hold parts where you like. Then nudge a bit while it starts to
set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering. Or just put
it
off center and solder one side of the part; once you do that it will
stay
in place while you do the other side.
For repairs it's usually enough to use residual solder. For fresh
installation you need to add some, of course. In the latter case,
solder
the board before you install the part and then you can clean up any
bridges. Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers. They fustrate me too. Lately, I have
to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.








--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"




Re: [OT] surface mount components

Tony Fleming
 

Great detail information Bob!
Thank you.

On Thu, May 16, 2019 at 11:51 AM Bob Albert via Groups.Io <bob91343=
yahoo.com@groups.io> wrote:

I would only use glue if other methods seem inadequate. It's a foreign
material that may cause long term problems. Not sure about that. That's
why I wouldn't use crazy glue or epoxy. The latter is so tenacious that
later repair may be difficult. So acrylic cement seems to be a good choice.
Frankly, I prefer the clamp method. It leaves no residue. As for having
the part orient itself, sometimes that doesn't work and you have a mess on
your hands. Heating all terminals simultaneously can be challenging also,
requiring special tools and good dexterity.
I always worry about overheating the part. So I try to work quickly
without rushing so as to minimize thermal stress.
ChipQuik has some products that can be useful but their stuff isn't
cheap. I try to get along without it because I don't do these things often
enough to justify having that around.
In the final analysis, my most useful tools are a fine tip soldering iron
for installation and, for removal of devices with several pins, hot air. I
have removed complex ICs, relays, connectors, and more with hot air. It
gets difficult if the part is through hole and bent over on the solder
side. Sometimes I lose patience and break a part while removing it,
thinking that surely it's hot enough. But wasn't. And my many years of
experience making cold solder joints makes me careful during installations.
There is no substitute for practice and experience. As the carpenter
says, measure twice and cut once. So don't assume anything, since each job
has quirks. A few moments of pondering how to do it is worth a lot.
Bob
On Thursday, May 16, 2019, 9:35:29 AM PDT, Glenn Little <
glennmaillist@...> wrote:

Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably
are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used
will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
One method that works for me is a small C clamp. I put the part about
where I want it and clamp it lightly. Then I nudge it into the exact
spot
and do the soldering. It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this. What also
may work is a dab of plastic acrylic cement. While it's liquid you can
use
it to hold parts where you like. Then nudge a bit while it starts to
set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering. Or just put
it
off center and solder one side of the part; once you do that it will
stay
in place while you do the other side.
For repairs it's usually enough to use residual solder. For fresh
installation you need to add some, of course. In the latter case,
solder
the board before you install the part and then you can clean up any
bridges. Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers. They fustrate me too. Lately, I have
to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.








--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"







Re: [OT] surface mount components

Richard Solomon
 

What does the heat do to the glue ?

Dick. W1KSZ

On Thu, May 16, 2019, 8:55 AM Tony Fleming <czecht@...> wrote:

Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
One method that works for me is a small C clamp. I put the part about
where I want it and clamp it lightly. Then I nudge it into the exact
spot
and do the soldering. It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this. What also
may work is a dab of plastic acrylic cement. While it's liquid you can
use
it to hold parts where you like. Then nudge a bit while it starts to
set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering. Or just put
it
off center and solder one side of the part; once you do that it will stay
in place while you do the other side.
For repairs it's usually enough to use residual solder. For fresh
installation you need to add some, of course. In the latter case, solder
the board before you install the part and then you can clean up any
bridges. Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:

On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers. They fustrate me too. Lately, I have
to
clean them with ISO to keep the parts from sticking from them.

I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.










Re: [OT] surface mount components

John Griessen
 

On 5/16/19 11:57 AM, Richard Solomon wrote:
What does the heat do to the glue ?
I was making a redesign of an infrared light comm system, where the optical glass
was epoxied to metal milled parts to make a telescope for sighting the IR beam in,
plus for holding lenses in. There were some jigs that held porro prisms in place
while glue was added from frozen epoxy syringes squirted by air pressure. After
putting the cold epoxy on, it hardened at room temperature and seemed "done" to the eye,
but there was an oven step yet to go. So an assembly gal that worked there in
a big room where things got made decided the jigs were not needed and should be put away
before going into the oven and loaded up the whole batch of telescopes made from prototype parts
and hit the button. The epoxy started to flow again for a while as the temperature went up
and stabilized. All the carefully placed porro prisms slid some and the aiming reticles were
all off because of it. There was no way to redo these. They were not tossed.
They could be used with lots of shimming, and that is what was done, even though this was a govt contract.
The production batches had big ALL CAPS notices about using those spring clip jigs going into the oven.

Re: [OT] surface mount components

Glenn Little
 

IPC J-STD-001G states:
7.4 Installation of Surface Mount Components Surface mounted device leads or components shall not [D1D2D3] be pressed down against the PCB land or other mating surface during the soldering operation or during solder solidification.

Note: Mechanically constrained devices such as connector securing tabs or holding a part over a pad from the sides during soldering is not the same as pressing the component down to the land.

The D1D2D3 above defines this violation as a defect for all three classes of circuit boards.

This IPC is titled:
Requirements for Soldered Electrical and Electronic Assemblies
and is the bible for circuit board assembly and rework.

Glenn

On 5/16/2019 12:51 PM, Bob Albert via Groups.Io wrote:
I would only use glue if other methods seem inadequate.  It's a foreign material that may cause long term problems.  Not sure about that.  That's why I wouldn't use crazy glue or epoxy.  The latter is so tenacious that later repair may be difficult.  So acrylic cement seems to be a good choice.
Frankly, I prefer the clamp method.  It leaves no residue.  As for having the part orient itself, sometimes that doesn't work and you have a mess on your hands.  Heating all terminals simultaneously can be challenging also, requiring special tools and good dexterity.
I always worry about overheating the part.  So I try to work quickly without rushing so as to minimize thermal stress.
ChipQuik has some products that can be useful but their stuff isn't cheap.  I try to get along without it because I don't do these things often enough to justify having that around.
In the final analysis, my most useful tools are a fine tip soldering iron for installation and, for removal of devices with several pins, hot air.  I have removed complex ICs, relays, connectors, and more with hot air.  It gets difficult if the part is through hole and bent over on the solder side.  Sometimes I lose patience and break a part while removing it, thinking that surely it's hot enough.  But wasn't.  And my many years of experience making cold solder joints makes me careful during installations.
There is no substitute for practice and experience.  As the carpenter says, measure twice and cut once.  So don't assume anything, since each job has quirks.  A few moments of pondering how to do it is worth a lot.
Bob
On Thursday, May 16, 2019, 9:35:29 AM PDT, Glenn Little <glennmaillist@...> wrote:
Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably
are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used
will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage.  The issue is especially bad
with fragile leadless parts like SMD capacitors.  If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
  One method that works for me is a small C clamp.  I put the part about
where I want it and clamp it lightly.  Then I nudge it into the exact spot
and do the soldering.  It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this.  What also
may work is a dab of plastic acrylic cement.  While it's liquid you can use
it to hold parts where you like.  Then nudge a bit while it starts to set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering.  Or just put it
off center and solder one side of the part; once you do that it will stay
in place while you do the other side.
For repairs it's usually enough to use residual solder.  For fresh
installation you need to add some, of course.  In the latter case, solder
the board before you install the part and then you can clean up any
bridges.  Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
      On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
  On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers.  They fustrate me too.  Lately, I have to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.






--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: [OT] surface mount components

David Kuhn
 

Hello Ravi,

I just ordered a set of Techman tweezers on Amazon for $12 with free next
day delivery:
TECKMAN Precision Tweezer Set,10 Pack Best ESD Tweezers Set Stainless Steel
Long Tweezers with Curved,Pointed,Slanted Tips for Eyebrow,Eyelash
Extension,Craft, Jewelry, Soldering & Laboratory Work
Product features

- [MULTI TYPES OF TWEEZERS]:This 10 in 1 precision tweezer kit include
different types of tweezers with different tips. 5 extra fine pointed
tweezers, 2 angled tweezers,2 flat tip tweezers including one mini slanted
tweezer which other jeweler tweezers set do not have in the market.
- [PORTABLE WITH TOOL BAG]:All tweezer tips were covered with protective
caps, helping users protected from getting hurt. All packed in a canvas
tool bag, compact and well-orgnized, easy to take out and return, portable
and easy to store for any standby applications.
- [ANTI-STAIC & NON-MAGNETIC]:These ESD safe plating tweezers have
electrostatic dissipative coating which helps protect electronic components
from static damage. Non magnetic tips help protect objects from sticking
and improve working efficiency.
- [WIDELY USED TWEEZERS SET]:A must have complete tweezers set for women
and men which can be used for eyebrow plucking, eyelash extension, ingrown
hair removal or kitchen, craft, jewelry, lab work, electronics repair and
other precision jobs.
- [DURABLE CONSTRUCTION]:These tweezers are made of high strength
stainless steel with excellent details.The front part edges were burnished
pretty well,very comfortable to hold in hand and easy to operate without
pains.



They look really nice, I'll get to see them later today.

Dave

On Wed, May 15, 2019 at 4:27 PM Ravi Moghe <ravimoghe@...> wrote:

On the point of tweezers set, I would suggest to visit Aliexpress.com.

I searched and found tweezers (straight point and curved point) that have
0.1mm tip size dimension.
With the sizes of SMDs now-a-days, it is better to have a set of very fine
point tweezers handy. And, one can get both tweezers in about 25 odd USDs
(delivered).

I also found that many a sellers on Amazon buy material from these sellers
available on aliexpress.com and supply in local market for high profits.

Hope this helps.

Warm Regards,




IMPORTANT: Photos are eating up our storage

 

Before we left Yahoo TekScopes was using about 1½GB of storage for our
posts. This meant our storage needs were too large to qualify for the free
version of Groups.io. That was fine because their Premium plan gives us 10GB
for a reasonable annual fee.



Quite by accident I discovered the other day that we are using it up rapidly
and more storage is out of the question.

This is a breakdown of what we are doing with our 10GB:

* TekScopes is currently using 5.2 GB total storage out of 10GB

* Attachments: 12 kB - 0% of 10GB

* Photos: 4.4 GB - 44% of 10GB

* Files: 733 MB - 7% of 10GB



The problem is this: To get more storage space the next plan Groups.io has
is the Enterprise plan. It gives us 1TB. BUT THIS PLAN COSTS $200 PER
MONTH!!! Our current plan costs $110 PER YEAR. So the Enterprise Plan is not
an option.



Photos are eating up our storage at an unsustainable rate. I estimate that
that are gobbling up 1½GB to 2GB per year. At that rate we will use up our
storage in 3 to 4 years. In all probability it will happen sooner since
photos are getting bigger not smaller and they are becoming easier to take
and post.



One of the things I notice about the photos is how many of them were posted
to deal with a specific problem that has since been solved. Do we need to
keep the photos forever in cases like this? If not how can we insure they
are removed at an appropriate time.



I would appreciate your suggestions particularly if they are about how other
Forums handle this problem.



Dennis Tillman W7PF

Re: IMPORTANT: Photos are eating up our storage

Ilya Tsemenko
 

Photo archival could be life and death question for some of older equipment, as finding know-how or older equipment troubleshooting or even teardown photos to find out stuff like cable harness photos is always a problem. I'm sure everyone here was upset at least once,  finding some obscure bit of repair blog post about beloved Tek/Fluke/Keithley/HP gear but with missing files/photos/PDFs..

I can offer unlimited space for free for the preservation and archive purpose, if there is easy way to pull/mirror the group contents. Have own server with plenty of storage space, that is accessible online.

BR, Illya Tsemenko
xDevs.com

On 5/17/2019 1:49 AM, Dennis Tillman W7PF wrote:
Before we left Yahoo TekScopes was using about 1½GB of storage for our
posts. This meant our storage needs were too large to qualify for the free
version of Groups.io. That was fine because their Premium plan gives us 10GB
for a reasonable annual fee.


Quite by accident I discovered the other day that we are using it up rapidly
and more storage is out of the question.

This is a breakdown of what we are doing with our 10GB:

* TekScopes is currently using 5.2 GB total storage out of 10GB

* Attachments: 12 kB - 0% of 10GB

* Photos: 4.4 GB - 44% of 10GB

* Files: 733 MB - 7% of 10GB


The problem is this: To get more storage space the next plan Groups.io has
is the Enterprise plan. It gives us 1TB. BUT THIS PLAN COSTS $200 PER
MONTH!!! Our current plan costs $110 PER YEAR. So the Enterprise Plan is not
an option.


Photos are eating up our storage at an unsustainable rate. I estimate that
that are gobbling up 1½GB to 2GB per year. At that rate we will use up our
storage in 3 to 4 years. In all probability it will happen sooner since
photos are getting bigger not smaller and they are becoming easier to take
and post.


One of the things I notice about the photos is how many of them were posted
to deal with a specific problem that has since been solved. Do we need to
keep the photos forever in cases like this? If not how can we insure they
are removed at an appropriate time.


I would appreciate your suggestions particularly if they are about how other
Forums handle this problem.


Dennis Tillman W7PF



Re: OT: I/V curve tracing made easy with Python and PyVISA

Albert Otten
 

A basic introduction corresponding to what Magnus does in his script is here for example:
https://www.edn.com/design/test-and-measurement/4441692/How-to-automate-measurements-with-Python
I tried Python successfully for command communication (both serial and GPIB) with my CSA803 but only to verify that it is possible.
(Magnus, I guess "a lot of water has flown through the river Rhein" while you composed that Python script ;-)

Albert

Re: [OT] surface mount components

Craig Sawyers
 

I was making a redesign of an infrared light comm system, where the optical glass was epoxied to
metal milled parts to make a telescope for sighting the IR beam in, plus for holding lenses in.
There
were some jigs that held porro prisms in place while glue was added from frozen epoxy syringes
squirted by air pressure. After putting the cold epoxy on, it hardened at room temperature and
seemed "done" to the eye,
but there was an oven step yet to go.
That brings back memories of assembling parts of an astronomical telescope instrument that went on
Gemini South in Chile. This was an echelle spectrograph. Cross dispersion was two 20cm side fused
silica prisms worth the equivalent of $100k each that had to be adhesively bonded onto a stress
relieved , webbed invar plate. I'd found the right epoxy, black in colour, with the right viscosity.
Measured out the resin and hardener using a chemical balance. 20 minute life after mixing - so it
was touch and go. Three people needed to be coordinated to get those prisms in the right place
before the adhesive went off. There was a breath of relief when that worked out.

Craig

Re: IMPORTANT: Photos are eating up our storage

Glenn Little
 

Could photos that have been posted for over a predetermined time be resized?
This should free up storage area and retain the photos for history.
If the photo author is posted with the photo, and someone needs a higher resolution photo, they could contact the author.

Just an idea.

Glenn
WB4UIV

On 5/16/2019 1:49 PM, Dennis Tillman W7PF wrote:
Before we left Yahoo TekScopes was using about 1½GB of storage for our
posts. This meant our storage needs were too large to qualify for the free
version of Groups.io. That was fine because their Premium plan gives us 10GB
for a reasonable annual fee.


Quite by accident I discovered the other day that we are using it up rapidly
and more storage is out of the question.

This is a breakdown of what we are doing with our 10GB:

* TekScopes is currently using 5.2 GB total storage out of 10GB

* Attachments: 12 kB - 0% of 10GB

* Photos: 4.4 GB - 44% of 10GB

* Files: 733 MB - 7% of 10GB


The problem is this: To get more storage space the next plan Groups.io has
is the Enterprise plan. It gives us 1TB. BUT THIS PLAN COSTS $200 PER
MONTH!!! Our current plan costs $110 PER YEAR. So the Enterprise Plan is not
an option.


Photos are eating up our storage at an unsustainable rate. I estimate that
that are gobbling up 1½GB to 2GB per year. At that rate we will use up our
storage in 3 to 4 years. In all probability it will happen sooner since
photos are getting bigger not smaller and they are becoming easier to take
and post.


One of the things I notice about the photos is how many of them were posted
to deal with a specific problem that has since been solved. Do we need to
keep the photos forever in cases like this? If not how can we insure they
are removed at an appropriate time.


I would appreciate your suggestions particularly if they are about how other
Forums handle this problem.


Dennis Tillman W7PF




--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: IMPORTANT: Photos are eating up our storage

Tom Gardner
 

Roughly how many photos are there in the 4.4GB?

Most of the photos I post on other forums don't need to be any larger than 1000*800, and they take ~250kb of storage. I find heavy clipping and then resizing them to be effective and acceptable in most cases.

Might it be appropriate to reject larger photos?
For the few photos that need to be larger, perhaps a (the?) moderator might need to OK them.

On 16/05/19 18:49, Dennis Tillman W7PF wrote:
Before we left Yahoo TekScopes was using about 1½GB of storage for our
posts. This meant our storage needs were too large to qualify for the free
version of Groups.io. That was fine because their Premium plan gives us 10GB
for a reasonable annual fee.


Quite by accident I discovered the other day that we are using it up rapidly
and more storage is out of the question.

This is a breakdown of what we are doing with our 10GB:

* TekScopes is currently using 5.2 GB total storage out of 10GB

* Attachments: 12 kB - 0% of 10GB

* Photos: 4.4 GB - 44% of 10GB

* Files: 733 MB - 7% of 10GB


The problem is this: To get more storage space the next plan Groups.io has
is the Enterprise plan. It gives us 1TB. BUT THIS PLAN COSTS $200 PER
MONTH!!! Our current plan costs $110 PER YEAR. So the Enterprise Plan is not
an option.


Photos are eating up our storage at an unsustainable rate. I estimate that
that are gobbling up 1½GB to 2GB per year. At that rate we will use up our
storage in 3 to 4 years. In all probability it will happen sooner since
photos are getting bigger not smaller and they are becoming easier to take
and post.


One of the things I notice about the photos is how many of them were posted
to deal with a specific problem that has since been solved. Do we need to
keep the photos forever in cases like this? If not how can we insure they
are removed at an appropriate time.


I would appreciate your suggestions particularly if they are about how other
Forums handle this problem.

Re: IMPORTANT: Photos are eating up our storage

Carsten Bormann
 

Could photos that have been posted for over a predetermined time be resized?
This should free up storage area and retain the photos for history.
It will also destroy all the crucial detail that can make the photos so valuable.

If the photo author is posted with the photo, and someone needs a higher resolution photo, they could contact the author.
Who by then might be a silent key.
(Or simply not have them any more — who here has perfect archival discipline with those?)


Note that we are talking about reaching 10 GB, within a few years.
10 GB is about 20 cents worth of storage today.
We don’t even know what the groups.io tiers and limits will be in 3 or 4 years.
(It might be worth alerting them to the fact that their tiers will stop working for us in that time frame.)

So apart from a general request to maybe use a little bit of discretion with respect to file sizes when posting photos, there is no need for destructive action at this point.

Grüße, Carsten

Re: OT: I/V curve tracing made easy with Python and PyVISA

Tony Fleming
 

Thank you Albert!

On Thu, May 16, 2019 at 1:18 PM Albert Otten <aodiversen@...> wrote:

A basic introduction corresponding to what Magnus does in his script is
here for example:

https://www.edn.com/design/test-and-measurement/4441692/How-to-automate-measurements-with-Python
I tried Python successfully for command communication (both serial and
GPIB) with my CSA803 but only to verify that it is possible.
(Magnus, I guess "a lot of water has flown through the river Rhein" while
you composed that Python script ;-)

Albert



Re: IMPORTANT: Photos are eating up our storage

 

Hi Carsten,
You make a good point about the loss of what might be crucial detail if existing photos are compressed.
If we can limit the size of future photos (I have to check if that is possible) then it means the author will have to focus in on the important information he/she is trying to convey and crop the irrelevant surroundings.

I often find the pictures posted to our photos section have the briefest of explanations which leaves me wondering where I am supposed to direct my attention. My personal preference when documenting a problem is to placing photos in a PDF document with running comments alongside and in-between photos to explain what the reader is looking at. PDFs are more compact and the accompanying text serves two purposes: 1) As the author describes his/her photos in the document it forces them to think about what is going on and sometimes that leads them to the solution; 2) It provides the reader with more information which speeds up finding the cause of the problem.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Carsten Bormann
Sent: Thursday, May 16, 2019 11:57 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] IMPORTANT: Photos are eating up our storage


Could photos that have been posted for over a predetermined time be resized?
This should free up storage area and retain the photos for history.
It will also destroy all the crucial detail that can make the photos so valuable.

If the photo author is posted with the photo, and someone needs a higher resolution photo, they could contact the author.
Who by then might be a silent key.
(Or simply not have them any more — who here has perfect archival discipline with those?)


Note that we are talking about reaching 10 GB, within a few years.
10 GB is about 20 cents worth of storage today.
We don’t even know what the groups.io tiers and limits will be in 3 or 4 years.
(It might be worth alerting them to the fact that their tiers will stop working for us in that time frame.)

So apart from a general request to maybe use a little bit of discretion with respect to file sizes when posting photos, there is no need for destructive action at this point.

Grüße, Carsten




--
Dennis Tillman W7PF
TekScopes Moderator

Re: IMPORTANT: Photos are eating up our storage

Carsten Bormann
 

On May 16, 2019, at 22:07, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Hi Carsten,
You make a good point about the loss of what might be crucial detail if existing photos are compressed.
If we can limit the size of future photos (I have to check if that is possible) then it means the author will have to focus in on the important information he/she is trying to convey and crop the irrelevant surroundings.
Wrong direction of movement. The direction should be making it easier to contribute, not harder. While I’d love it when people to spend effort making good contributions, not everybody knows how to do this. (Ceterum censeo: if the images are sent as attachments, you have the context of the mail message, which is usually much more useful. Can we fix this?)

I often find the pictures posted to our photos section have the briefest of explanations which leaves me wondering where I am supposed to direct my attention.
There we are. Put them in the message, and there is a natural place for that explanation.

My personal preference when documenting a problem is to placing photos in a PDF document with running comments alongside and in-between photos to explain what the reader is looking at.
My personal preference is to do the same, but in a mail message.
(Which doesn’t mean your preference is wrong, but you can’t extrapolate it to all of even a majority of the contributors.)

PDFs are more compact
Generally only if they employ heavy compression, and there we are with the loss of detail.
There are many tools for creating PDFs, most of which don’t handle natural images (photos) very well.

and the accompanying text serves two purposes: 1) As the author describes his/her photos in the document it forces them to think about what is going on and sometimes that leads them to the solution;
Yes. Put them in the message.

2) It provides the reader with more information which speeds up finding the cause of the problem.
Yes. Put them in the message.

I think the photos section is great when people want to document something with an explicit archival intent, and that’s where creating PDFs can (but still often won’t) be a good approach. The Tek wiki may be a better place for this archival intent, though.

Grüße, Carsten