Tag Archive | Wall clock

The return of PQNG

Much to my surprise, after donating a CPU module (used in PQNG) to Jope / Extend to play around with, he managed to get it running Linux from a CF-card. Pinging local host, is there any more inherent use for any computer system running Linux? ;).. Now, I have no certainty why this boot media didn’t work for me the first time around, but inspired by Jope’s success I decided to give them a second spin.. And what do you know, PQNG booting from a CF!

This time around, what changed was that I had some smaller CF cards and a factory-made IDE-to-CF adapter. The adapter I built myself wasn’t the source of problems (works fine on my desktop PC), so I’m guessing there has to be some kind of low-level differences between CF-cards other than their size. Could also be a newer BIOS on the CPU module. Back in 2008, the cards I tested were all above 1Gb whereas they’ve now been below 256Mb. Out of what I’ve tested so far, the failed ones have been a 256Mb Transcend and a 32Mb Canon. Then again, to contrast this I also have a second 32Mb Canon that works just fine.

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Continuing a bit with the Pqng project, I constructed a second unit for Melwyn in return for making the software. I had been thinking about a desktop model and as Melwyn preferred it over a wall-mount one I decided to give it a spin. Besides the power supply (stripped from a DVD player), the hardware is the same as before.

Pqng2, assembly frame

Modified assembly frame with the CPU and backlight transformer installed.

The “desktop model” is simply equipped with a stand that keeps the unit in a upright position. I decided to test integrating the power connector to the stand.. with proper insulation added of course.

Pqng2, stand

Support stand

Pqng2, stand & PSU

PSU connector mounted to support stand

If the power connector was mounted to the unit itself, it could be easily converted to a wall-mount model. This would require reorganizing the sub-component layout as there really isn’t room for the connector in the current one.

Pqng2, rear view of assembled unit

Rear view of assembled unit.

Pqng2, PSU close-up

PSU connector

Pqng2, reset switch

Reset switch soldered directly to CPU module.

I decided to test “bundling up” the floppy cable by cutting it to smaller stripes and wrapping them together with some twist ties. Apparently, this a mod some computer geeks use to make the cables less wide so that when installed inside a computer, they cables don’t obstruct airflow as much :)

Pqng2, side view

Side view of completed unit.

Pqng2, first boot

First boot..

Adding some kind of a boot-time display turn-on control would definitely make Pqng more ‘classy’ in a way. So to say, to prevent the bootup screens (BIOS etc.) from appearing on-screen. Probably the easiest option would be to add a simple RC time circuit to the +12VDC backlight inverter power supply. This could turn the backlight on, say, 20 seconds after power-up.

Pqng2, complete

..and off it goes!

Other than that, the floppy drive is becoming the biggest downside of Pqng design. It’s simply too unreliable and oversized in regard to other sub-modules. No idea what to use instead.

I have tried testing a selection CF-cards of different brands/sizes with no luck; the CPU module refused to detected them (or wrongly detected the size). The CPU does have a Disk-On-Chip socket, but these chips are way too expensive for this (and likely any) project. Not sure if something else could be shoehorned to the socket though..?


Let’s get the most important out of the way: This project is heavily inspired by the one conceived by Sander Mulder. If you haven’t come across it by now, check it out!

After having had the Sander’s screensaver version (available at the website) running on my computer for some time, I started thinking about making a similar device.. No surprise, that the hardware from the ‘Kettlers of Satan‘ project turned out a obvious choice shortly after. Melwyn / Haujobb agreed to help with the software and so, the project was underway! :)

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