tayda led users - questions for

[duck_arse]

if we agree that we can identify the Kathode of a led by
* the body flat
* the shorter lead
* the larger flattened anvil/heatsink/reflector holding the die and visible thru the envelope,

then the other lead must be the Anode.


my parts from tayda lobbed yesterday, tonight I decided to test them for brights and colour match. the first bag ("LED 5mm Red Water Clear Ultra Bright" SKU:A-706) - as I forget which lead is short, but can see the anvil easy, I use that to identify the Kathode, connected a string of four to a CLR and supply, switched on. darkness.

eliminating the possible failure points, I arrived at the leds, pulled three to test one - darkness. so I did what anyone would do, and turned it around. what do you know - light. I had a closer look at the leds themselves - the body flat lines-up with the anvil, but also the long lead (and the Anode). which makes no sense, even though plugging the string in backwards does indeed produce solid state light.

and while this will bother me not at all in my builds, I wondered how many people have non-working indicator leds. further ponderation, how is it possible to even have the die backwards, and still work? upside-down?


and a question for users - if I said this led is "ultra bright" and this led is "super bright", which led would you think would be brighter?

[Kipper4]

I had a similar issue years back. Im sure I still have some of the blighters somewhere.


My guess is the Ultra bright......

Did I win the sausage?

[bluebunny]

I think this may be a thing.  Those "rules" are often caveated (is that a word?) with the disclaimer: "works for almost all LEDs".  Here's an example: no flat, short anode. 

(And it might explain some prior episodes of my own where I put it down to being too tired or drunk...)

[blackieNYC]

Thanks to that diagram, I will remember that the smaller part of the two visible shapes within is the anode.
I also have a bag of 30-40 year old LEDs with reversed legs. Original Studer parts, no less. Hard to imagine such a standard was established so recently.

[duck_arse]

blackie - thanks to that diagram, you should now know to test all tayda leds.

bluebunny - how drunk?

and the answer, after I thort about it (having been blinded by the super bright greens), was super is brighter - following the radio speed nomenclature, very, ultra, super, err even more biggerer.

I'm also wondering how the manufacturer managed to put the die upside-down on the anvil (see diagram). they must have some idea of what they are doing at the factory, surely.

[merlinb]

I have to deal with LED sourcing at work -I've had to test at least a hundred different model numbers. Looking at my collection I'd say the anvil appears on the ANODE in about 10% of cases. But only in two cases have I come across LEDs where the flat was on the anode side (but lots have no flat at all), and another where the long lead was the cathode.

A similar thing happens with surface mount LEDs which have a little arrow printed on them to incidate the... whatever the manufacturer wants it to indicate!

[bluebunny]

bluebunny - how drunk?

If only I could remember.  Us bunnies aren't renowned for our alcohol absorption.   

Anyroad, I think this is about time I put together permanent versions of all these handy little test circuits that I can call upon as I build stuff.  Rather than emerging from a stupor wondering why my lights aren't...

[bluebunny]

which led would you think would be brighter?

The one that can do mental arithmetic without having to take their socks off...   

[duck_arse]

Us bunnies aren't renowned for our alcohol absorption

not true. many's the time I've mopped-up an overturned schooner with a bunny rabbit.

[antonis]

the Kathode of a led

There isn't such a thing..!!! 

(Cathode, maybe..)