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Old October 12th 17, 11:58 AM posted to uk.tech.digital-tv
MR
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Posts: 22
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


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