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[OT] LED polarity etc



 
 
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  #1  
Old October 11th 17, 10:04 PM posted to uk.tech.digital-tv
pinnerite
external usenet poster
 
Posts: 93
Default [OT] LED polarity etc

It is not often that I point a soldering iron at anything but I wanted to
add a switch and an LED to a battery powered function generator about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from the early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished that.
The first thing was which way round to connect an LED. I have a substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal flat plate
should be negative and the longer lead positive. Except on mine it was the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch before
soldering it to the board, plus the two components and the leads to the PP3
battery. It should have been easy. The solder would not flow. There was no
flux on the board and it looks like the solder, purchased from Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.


--
Mageia 5.1 for x86_64, Kernel:4.4.82-desktop-1.mga5
KDE version 4.14.5 on an AMD Phenom II X4 Black edition.

  #2  
Old October 11th 17, 10:16 PM posted to uk.tech.digital-tv
David Woolley[_2_]
external usenet poster
 
Posts: 538
Default [OT] LED polarity etc

On 11/10/17 22:04, Pinnerite wrote:
We use to use lead/tin solder but it appears 'elf-n-safety abolished that.


It's easy to get tin/lead solder
https://www.rapidonline.com/catalogue/search?Query=solder&Attributes={%22Leaded%20%2F%20 Lead-Free%22:[%22Leaded%22]}&ResultsTotal=65.

Whilst there are restrictions on commercial use, it is still available
for personal use, and also for some high reliability professional uses.
  #3  
Old October 11th 17, 10:17 PM posted to uk.tech.digital-tv
Tweed[_3_]
external usenet poster
 
Posts: 23
Default [OT] LED polarity etc

Pinnerite wrote:
It is not often that I point a soldering iron at anything but I wanted to
add a switch and an LED to a battery powered function generator about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from the early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished that.
The first thing was which way round to connect an LED. I have a substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal flat plate
should be negative and the longer lead positive. Except on mine it was the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch before
soldering it to the board, plus the two components and the leads to the PP3
battery. It should have been easy. The solder would not flow. There was no
flux on the board and it looks like the solder, purchased from Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.



Tin/lead solder is still freely available. E.g.
http://cpc.farnell.com/multicore-sol...50g/dp/SD00959

There are many industries where it's use is allowed, mainly where you don't
want things to go wrong.

  #4  
Old October 11th 17, 11:24 PM posted to uk.tech.digital-tv
Max Demian
external usenet poster
 
Posts: 3,857
Default [OT] LED polarity etc

On 11/10/2017 22:16, David Woolley wrote:
On 11/10/17 22:04, Pinnerite wrote:
We use to use lead/tin solder but it appears 'elf-n-safety abolished
that.


It's easy to get tin/lead solder
https://www.rapidonline.com/catalogue/search?Query=solder&Attributes={%22Leaded%20%2F%20 Lead-Free%22:[%22Leaded%22]}&ResultsTotal=65.


Whilst there are restrictions on commercial use, it is still available
for personal use, and also for some high reliability professional uses.


It's possible the OP has an old soldering iron which isn't hot enough to
melt lead free solder.

I bought some supposed lead/tin solder (63% tin) from China via Amazon
https://www.amazon.co.uk/dp/B00GJN08SQ/ for £2.73 post free a while ago,
and it is really hard to use compared to the few inches of old stuff I
have. The stuff from Rapid might be better, but it will cost you £4.67
for 100g (+ £3.99+VAT p&p unless you buy it with other stuff).

--
Max Demian
  #5  
Old October 12th 17, 07:35 AM posted to uk.tech.digital-tv
Woody[_5_]
external usenet poster
 
Posts: 1,794
Default [OT] LED polarity etc


"Pinnerite" wrote in message
news
It is not often that I point a soldering iron at anything but I
wanted to
add a switch and an LED to a battery powered function generator
about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from
the early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished
that.
The first thing was which way round to connect an LED. I have a
substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor
was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal
flat plate
should be negative and the longer lead positive. Except on mine it
was the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch
before
soldering it to the board, plus the two components and the leads to
the PP3
battery. It should have been easy. The solder would not flow. There
was no
flux on the board and it looks like the solder, purchased from
Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.



The cathode always has a flat on the edge of the LED case against it.

In terms of current calculations, take your supply voltage minus 2V
and multiply it by 100 to give you the value of resistor taking the
next lower preferred value. Why? Most resistors work quite well on
10mA of current but typically anything in the range 10-20mA will do.

15-2=13 x100=1300, next preferred value down is 1K2.

Simples?


--
Woody

harrogate3 at ntlworld dot com


  #6  
Old October 12th 17, 09:06 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 6,944
Default [OT] LED polarity etc

Yes it always used to pay to keep a roll of old solder.
I gave mine to a friend when it became too dangerous to use a soldering
iron.

Of course veroboard is bare copper and that is probably the issue.
LED polarity seemed always to be non standard when I used them. those super
bright red ones you could get in huge packs from the old tandy stores were
all over the place.

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Pinnerite" wrote in message
news
It is not often that I point a soldering iron at anything but I wanted to
add a switch and an LED to a battery powered function generator about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from the
early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished that.
The first thing was which way round to connect an LED. I have a
substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal flat
plate
should be negative and the longer lead positive. Except on mine it was the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch before
soldering it to the board, plus the two components and the leads to the
PP3
battery. It should have been easy. The solder would not flow. There was no
flux on the board and it looks like the solder, purchased from Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.


--
Mageia 5.1 for x86_64, Kernel:4.4.82-desktop-1.mga5
KDE version 4.14.5 on an AMD Phenom II X4 Black edition.



  #8  
Old October 12th 17, 12:58 PM posted to uk.tech.digital-tv
MR
external usenet poster
 
Posts: 26
Default [OT] LED polarity etc

On Wednesday, 11 October 2017 22:04:54 UTC+1, Pinnerite wrote:
It is not often that I point a soldering iron at anything but I wanted to
add a switch and an LED to a battery powered function generator about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from the early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished that.
The first thing was which way round to connect an LED. I have a substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal flat plate
should be negative and the longer lead positive. Except on mine it was the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch before
soldering it to the board, plus the two components and the leads to the PP3
battery. It should have been easy. The solder would not flow. There was no
flux on the board and it looks like the solder, purchased from Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.


Don't you think that your problem stems from all the lead vapour you inhaled whilst soldering with good old-fashioned solder?

Joking aside, [select favourite deity - if appropriate] knows how much lead I ingested - I used to hold the stuff in my mouth as a third hand (often required when soldering loose components).

I used to love the small of flux - better than a Capstan Full Strength.

MR


--
Mageia 5.1 for x86_64, Kernel:4.4.82-desktop-1.mga5
KDE version 4.14.5 on an AMD Phenom II X4 Black edition.


  #9  
Old October 13th 17, 08:37 AM posted to uk.tech.digital-tv
pinnerite
external usenet poster
 
Posts: 93
Default [OT] LED polarity etc

David Woolley wrote:

On 11/10/17 22:04, Pinnerite wrote:
We use to use lead/tin solder but it appears 'elf-n-safety abolished
that.


It's easy to get tin/lead solder

https://www.rapidonline.com/catalogue/search?Query=solder&Attributes={%22Leaded%20%2F%20 Lead-Free%22:[%22Leaded%22]}&ResultsTotal=65.

Whilst there are restrictions on commercial use, it is still available
for personal use, and also for some high reliability professional uses.


I use so little but that is a very useful link. Thank you.

Alan


--
Mageia 5.1 for x86_64, Kernel:4.4.82-desktop-1.mga5
KDE version 4.14.5 on an AMD Phenom II X4 Black edition.

  #10  
Old October 13th 17, 10:11 PM posted to uk.tech.digital-tv
Ian Field
external usenet poster
 
Posts: 160
Default [OT] LED polarity etc



"Tweed" wrote in message
news
Pinnerite wrote:
It is not often that I point a soldering iron at anything but I wanted to
add a switch and an LED to a battery powered function generator about the
size of a fat credit card.

I decided a strip of Vero board would do and had a few scraps from the
early
'70s.

We use to use lead/tin solder but it appears 'elf-n-safety abolished
that.
The first thing was which way round to connect an LED. I have a
substantial
stock of components but no idea of the spec of the LEDs.

Calculating the value of a suitable current limiting serial resistor was
easy enough but which way round should the leads go?

A quick web surf and I appeared to have the answer, the internal flat
plate
should be negative and the longer lead positive. Except on mine it was
the
opposite.

Anyway I had to drill the tiny board to mount the toggle switch before
soldering it to the board, plus the two components and the leads to the
PP3
battery. It should have been easy. The solder would not flow. There was
no
flux on the board and it looks like the solder, purchased from Maplin did
not have the cores of the Multicore that I was used to.

I'm beginning to dislike progress. I must have got old when I wasn't
looking.



Tin/lead solder is still freely available. E.g.
http://cpc.farnell.com/multicore-sol...50g/dp/SD00959

There are many industries where it's use is allowed, mainly where you
don't
want things to go wrong.


"Miracles we do at once - the impossible takes a little longer". The
manufacturers are starting to cope with this RoHS crap, but its still
causing a lot more electronics waste.

 




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