HP-41 external big display. (just kidding... sort of)

[Diego Diaz]

Hi all,

Let's face it up, we're not getting younger.

As time goes by our sight is becoming poorer; so, when I spotted an old HP instrument faceplate on eBay sporting a couple of big displays I couldn't resist. :-)

Hooked it up to my CX (messy wiring is my friend... ;-) and "voilà!" huge characters for everyone to see.

Just before you ask; no, this is not intended for production, it's a mere hacking exercise just for the joy of it.

All the best from the Caribbean.

Diego.

https://photos.app.goo.gl/d4tDpTrx34s2bwD39

[Ren]

(11-25-2024 12:15 AM)Diego Diaz Wrote:  Let's face it up, we're not getting younger.

As time goes by our sight is becoming poorer; so, when I spotted an old HP instrument faceplate on eBay sporting a couple of big displays I couldn't resist. :-)

Hooked it up to my CX (messy wiring is my friend... ;-) and "voilà!" huge characters for everyone to see.

Just before you ask; no, this is not intended for production, it's a mere hacking exercise just for the joy of it.

https://photos.app.goo.gl/d4tDpTrx34s2bwD39

So, the display is from an "old HP instrument" ?
I'm just playing with the thought of replacing broken Bubble LED displays with LCD. (Blasphemy!)
(Maybe someone has already done that)

[Diego Diaz]

Hi Ren,

Yes, namely from an "HP-3852A Data Acquisition Control Unit" front panel.

AFAIK this is the only one using two 12 character LCD displays.

I know of other instruments (e.g. 4273A LCR meter) using a 24 character LCD display, and it would be great to test one of these. Alas, I've yet to find a cheap front panel with LCD.

Good luck with your LED -> LCD conversion. ;-)

Cheers.

Diego.

[HPing]

Nice HP project. You could put it above the calculator on a stand for desktop use.

Here is a supplier of e-paper and "easy" drivers if you want the ultimate in easy viewing.
https://www.waveshare.com/product/displays/e-paper.htm
https://www.waveshare.com/product/displa...boards.htm

I don't think the optimisation is particularly easy.

[ThomasF]

(11-25-2024 12:15 AM)Diego Diaz Wrote:  Hooked it up to my CX (messy wiring is my friend... ;-) and "voilà!" huge characters for everyone to see.

Nice work and a nice display!

For anyone that might be interested, the Tulip board offers a easy way to extend the display.
In my prototype I added a much smaller display, hooked up via I2C, as shown in e.g. this post.
The display is not as nice as the big HP LCD as shown by Diego, but can show not only the main display but also all annunciators.
Or, the display commands could be forwarded to a PC, showing the display on a big monitor.
All this is done by emulating the 41 display in the Pico device by listening to the instruction on the bus and keep any kind of display updated.

Cheers,
Thomas

[MeindertKuipers]

(11-25-2024 12:15 AM)Diego Diaz Wrote:  Let's face it up, we're not getting younger.

Just before you ask; no, this is not intended for production, it's a mere hacking exercise just for the joy of it.
https://photos.app.goo.gl/d4tDpTrx34s2bwD39

Nice hack Diego. Thomas mentioned a possible way of doing this, but all the other hackers here, including myself, are curious as how you achieved controlling the big display.

[STOX]

Next; A proper docking station for the 41.

[KeithB]

Or get HPIL and the video adapter. Hook it up to your 50 inch HDTV, and voila! big display, with all the stack. minus some annuciators.

[Diego Diaz]

Hi all,

The annunciators are already there: twelve small arrows under the digits.

Some lettering must be added on the bottom to show the different functions: USER, BAT, Flags, PRGM, ALPHA, etc.

The display interface chips are the same used in the 41, hence it can be connected to the lines from any I/O port.

Some resistor divider must be included to provide the required V1, V2 and V3 to the LCD. But apart for that, a limiting resistor for the Vcc line and a 470pF capacitor for the internal oscillator; only standard signals are required: Phi1, Phi2, SYNC, ISA, DATA and PWO.

These type of displays are used (with different annunciators) in several instruments from that era, e.g. 3468 & 3478 DMMs.

Enjoy your week!

Diego.

[MeindertKuipers]

Thanks for the clarification Diego,
Interesting to know that the exact same display controller has been re-used.

[Thomas Klemm]

(11-25-2024 12:15 AM)Diego Diaz Wrote:  As time goes by our sight is becoming poorer; so, when I spotted an old HP instrument faceplate on eBay sporting a couple of big displays I couldn't resist. :-)

Couldn't you just use a Fresnel lens as in the film Brazil:


(just kidding... sort of)

[Diego Diaz]

Hi Thomas, all,

Sure I could... but that shoudn't have been so funny. :-D

(Great movie BTW) ;-)

Cheers!

Diego.