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Old October 12th 17, 08:06 AM posted to uk.tech.digital-tv
Brian Gaff
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Posts: 6,808
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

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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.


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