HP-45 Green LED display

[LEDfan]

A few years ago there was a prototype HP-45 for sale with a green LED display. Does anyone know what happened to this? Just wondered if there were any photos of it floating around the internet, as hadn’t seen anything in the museum.

The link to a certain auction website in the archived thread is long dead, and despite a request from a fellow member, it seems like the seller did not share photos with the museum.

There seems to be an extract of the auction description with a couple of photos on a Swiss website, Calculator Nostalgia, just wondered if there are any more detailed photos, e.g. of the insides/ differences with a standard HP-45.

I’m also curious as to whether there are any other green LED calculators floating about (not vacuum fluorescent displays VFD, which seem to get misappropriated as LED displays).

Not an HP calculator, but there is an YouTuber Calculator Obsessed, that has shown a calculator with a green LED display (not VFD), but is labelled as a mystery calculator, and looks a bit home made/ modified, although it looks like a proper 9 digit seven segment green LED display. Curious to know if any others have seen this or where the display may have come from/ been used. Not sure if any other use case other than for a calculator or similar device.

[John Garza (3665)]

Amazing. A prototype 45 would place it in the early 70's.
I didn't think green LEDs were available or practical then.


Are you sure it wasn't a modern hack job?

-J

[LEDfan]

Apparently it was a prototype from the 1970s. Bill Hewitt had issue with seeing the red light from the LED displays clearly, and so one of the engineers worked on a green display. Ultimately it was too dim to be of use.

Here is a link to the Swiss website

I found this from a link from YouTuber Calculator Obssessed, in a comment under a green calculator display.

The Swiss website seems to match an archived thread from this website from 2011. HP-45 Green LED

[LEDfan]

The other calculator with a green LED display is shown here.

Calculator Obssessed has a couple of short videos featuring an HP-45, including this one. Sadly not with a green display, although I wish the label on a classic came off that easily for me.

Seems to be a bit of school kid humour in the videos.

[John Garza (3665)]

(07-08-2023 07:34 PM)LEDfan Wrote:  Ultimately it was too dim to be of use.

Yep.. that's what I thought... not practical. They were in the labs, but hadn't made it out in commercial use very much. Red was king back then.

-J

[John Garza (3665)]

I'd love to upgrade a 35 to modern blue LEDs.

[LEDfan]

Blue would look good, I can certainly see the appeal, especially if it gets a HP-35 with a failed display fully working again. Those original displays seem hard to get hold of; it took me a while to get hold of one to replace one of mine with a missing segment.

Personally I like the style of the 1970s LED display, mainly due to nostalgia and my calculators during school days (sadly not HP), but wish that the development of LEDs had been such that there was greater colour choice, hence my interest in the HP-45 with the green display.

There’s a few people who have developed TIL305 clones in a range of colours, but the form factor of this 5x7 matrix LED display lends itself to modern LEDs, and is still a relatively common display due to its long product lifecycle.

Blackjetrock’s current project with the HP-41 and the pico is interesting to me, as it uses an OLED display to show a copy of the calculator display, and could theoretically be used to replace the original LCD. I no longer have my HP-41C, as the LCD failed, and I sold on for spares. I like the idea of an HP-41 with a LED display.

[teenix]

You would probably have to replace the LED window as well, to a color that would enhance the green or blue LEDs otherwise they may appear as a red diffused mixture.

cheers

Tony

[LEDfan]

That’s a very good point.