A beamer build in a time when 4K meant 4000 pixels in total!
The 1541-III project has evolved and a new and better display has come up. Where the prototype had only a 2 line display, now the final version has a display capable of 6 lines. It is not text based but graphical. This LCD is from an old nokia telephone and can be bought new on marktplaats or ebay for a few euros. With some small modifications this display can be used as an frame inside a slide-projector. Since I did not have a slide-projector I decided to build one myself.
As you can see", it is a very simple build. All it contains is a transformer (230V to 12V), a 50W halogen lamp and a rectifier to generate the DC-voltage for the fan. Which is driven with 9V instead of 12 to reduce the noise, the airflow is still sufficient. Two sheets of thin glass isolate the hot air generated by the 50W a halogen bulb. A creditcard sized fresnel lens (sold as an portable unbreakable magnifying lens years) to flatten out the light from the lamp. And the LCD (84x48 = 4032 pixels) which was obtained from an old Nokia phone (the reflective foil was very gently removed and wires soldered directly to the connector pins of the controller build "into" the LCD. Then last but not least a lens, salvaged from an ordinary large magnifying glass. The total cost was under 20 Euro. If you try to replicate this, build a cardboard versions first, this works quickly and saves a lot of mathematical effort. I can assure you, working with low cost materials like these the trial and error method is much faster then the theoretical approach.
Above is shown an example of the image it can produce. Here you'll see (on the left) the splash screen of the 1541-III project. As a projection surface I used the bedroom-door. If you look closely you'll notice the door handle. Which gives you a nice reference of the size of the image (and it save me holding up a banana for scale). Now you can clearly see why this project is called 4K-pixel beamer as you can almost count every individual pixel, all 4032 of them.