When a CRT Isn’t Retro Enough: LEDs

When we think of an old-style computer terminal, it has a CRT screen: either one of the big 1970s VDUs with integrated keyboard, or maybe one from a later decade with more svelte styling. You would have found other displays in use in previous decades though, and one of them came our way that we think it worthy of sharing.

16 segments in action. (PD) Wikimedia Commons.

[Dan Julio] was given several tubes of Siemens DL1416B 4-digit 17-segment LED displays by a friend, and decided to use them as an unusual retro display for his terminal project. These devices are an alphanumeric display with a parallel interface that can show a subset of the ASCII character set as well as a cursor. He had 213 of them, so made plans for a 64 character by 16 line display, however on discovering a quantity of the parts were non-functional he had to scale back to 12 lines of 48 characters.

The terminal in action.
The terminal in action.

The displays are mounted on PCBs in groups of four, controlled by a PIC16F1459 and some shift registers. These boards are then daisy-chained via a TTL serial line. The whole display shares one of the three serial ports on a Teensy 3.1 with his retro keyboard that has its own PIC controller, the others serving a serial printer port and the terminal serial port. The Teensy software has two modes: serial terminal or a Tiny Basic interpreter, and the relevant repositories are linked from the project page.

Since each set of DL1416Bs takes 250 mA, the whole display consumes about 9 A at 5 volts. On top of that the keyboard uses another 500 mA, so a sufficiently powerful supply had to be incorporated. This is mounted along with the Teensy in a very well-made enclosure, and the whole is mounted on what looks like a surplus monitor stand for a very professional finish.

To take us through the terminal’s features he’s posted a YouTube video that we’ve placed below the break. It comes across as a surprisingly usable machine, as he logs into a Raspberry Pi and edits a file, and takes us through some features of the BASIC interpreter.

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Slick 16-segment POV hard drive clock

pov_hdd_clock

Hackaday reader [svofski] sent in a fantastic looking hard drive-based POV clock (Google Translation) created by a maker in the Sichuan province of China. The clock, like the one [svofski] built, relies on LEDs placed behind the spinning platter to create the POV effect.

Quite a few carefully placed cuts have been made to the platter, which make up the segments required to display both numbers and letters of the alphabet. This isn’t a simple 16-segment POV display however. The font uses a lot of sharp edges and odd segment lengths, so we’re guessing that quite a bit of care was taken in the production of this clock.

You can see a demonstration of the clock in the video embedded below, which shows off its ability to display numbers, text, as well as a handful of simple patterns. It looks like there are some details available on the designer’s site, however it is all in Chinese, and Google’s translation is questionable at best. If only we knew someone that could give us a hand with deciphering the inner-workings of this clock…

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10,000 watt fluorescent array

This is an array of flourescent tubes that form a display. The video above is just two modules of a ten module installation that [Valentin] and his team are showing at an exhibition in Berlin tomorrow. The connected modules form something of a scrolling 16-segment display (similar to the 17 segment display modules of the ninja party badges but much larger). They’re using triacs, optocouplers, DMX, and an Arduino to interface a computer with the 182 fluorescent tubes of the display. Check out a second video after the break to see (or be blinded by) all ten modules pulling 10,000 watts.

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