Early LEDs

[kalee20]

Well, as a quantum leap is a distinct jump, as opposed to a gradual movement, the use of the phrase is not inappropriate!

In the grand scheme of things, although changing from incandescent to LED is a distinct change of technology, the uptake and shift will be a gradual process, so much so that most people will not realise that a leap has been made. And that's got its parallel in quantum physics, where quantum leaps are so small that nobody realised that they are minute discrete steps instead of a continuous process.

[m0cemdave]

I have a couple of MV10A diodes here, still in their original packaging.

The labelling reads:
Monsanto
Electronic Special Products
Light Emitting Diode

Also a Green RS "LED2", part number 58-640-3

I'm guessing they must have been some of the first of their type, and probably rather expensive at the time. I think I acquired them long ago, in boxes of assorted components at radio rallies, and have kept them as museum pieces!

[Steve_Bell]

I bought my first blue LED in the mid-80s (I think) at a cost of £4 + VAT from RS Components. It is used as a power indicator on a valve amp I still use occasionally and is as bright as it was when new. It requires 20mA current to be normal brightness and was an unusual sight back in its day. Now, you can't escape blue LEDs.

[Ambientnoise]

I am sure that some test gear for the Navy had red LEDs, designed around 1972. I am “almost” sure that it also had an led seven segment clock display. This kit was battery operated, using 4000 series cmos and cost was not a consideration !

Ken

[turretslug]

Originally Posted by kalee20

The first blue one I saw for sale was from Electrovalue, £27 each and they had "(Really!!)" after the price. I'd have put this late 1980's but I don't have a life event to date it against.

That must have been around the time that I saw them in one of the supplier catalogues for £31 when other colours were pretty much a hundredth of the price. I've a feeling that that was 1988, but can't quite nail it down.

Now blue LEDs have become a plague, trivially expensive, with dozens on a package set of Christmas lights for a few quid. I think my favourite colour has to be the orange type- pretty much thermionic glow colour, I've been known to connect them in series with capacitor bleeders in semiconductor stuff for an internal glow through the vents. Next is probably the high-efficiency red, nearer orange than the cherry-red of early types.

I can't help thinking that that the early cherry-red was falling off the edge of the human eye response, as well as the LEDs themselves being less efficient, they really did need 20mA for good visibility, modern types can be really bright with just 3 or 4mA.

[Bill]

I started work at Ferranti Electronics in Oldham in 1969. One section of the Mill was prototyping LEDs, though they were called something like GaP(?) diodes then. They were tiny tubular devices about 1mm diameter with gold tape connecting leads. The first ones were signal red and there was great excitement when a few green ones were manufactured.The cost of those prototypes must have been huge. Sometime later I blagged a few dim rejects, red and green and made a flashing tie-pin(remember them?) mounting them on a gold plated TO- 5 header with a cable to a control unit and battery, this was no later than 1970.

[emeritus]

Looking through my old electronics distributors' catalogues, the latest one I have is an ESD (formerly STC) from 1993. The only colours offered for LEDs are red, yellow, amber, and green, plus high intensity red and green and bi-colur red/green. No blues.

[Silvered_Mica]

Reading this thread has reminded me of my first blue LED, it would have been around 1988-89 and my friends dad had just liberated a box of PCB's from a skip at his works as he knew I was into electronics so he got them for me to use as stripper boards.
The box contained a load of plug in daughter cards in aluminium frames, some of them had those multi turn precision pots, numerous DIP switches and if memory serves correct lots of CMOS logic chips. I have no idea what they were out of but one of them had a single LED on it's face plate, a few months later I powered up the LED to see what colour it was and to my amazement I had a blue glow
I didn't even know they existed let alone know that i was in possession of one. It was OK as a panel indicator as long as it wasn't in direct light then you couldn't see it to well.

As far as blue LED's go now I think they have been over used I prefer purple these days as they are seldom used so I use them in projects and have replaced lots of LED's for purple ones.