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 Post subject: Vapour's Minimig Laptop
PostPosted: Fri Jan 14, 2011 7:14 pm 
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Hello Benheck forum goers!

I am vapour, but you may know me as paul, a somewhat frequent contributor to Hackaday, my projects can be found here. I come here because I am beginning work on a minimig based laptop not unlike the one found here by user "MegatronUK".

I am currently at the planning stage of the design and am assessing what criteria this laptop should contain. My current planning is shown below:

requirements
**SCREEN: need to determine ideal input method and aspect ratio.
**BATTTERY: need to asses system requirements (current draw)
BOARD: minimig http://amigakit.leamancomputing.com/catalog/?currency=CAD&currency=CAD
MOUSE: (synaptics touchpad?) a port for mouse. already have PS/2 mouse, need a touchpad...
KEYBOARD: slim keyboard with a port for an external keyboard. http://www.dealextreme.com/details.dx/sku.1846
JOYSTICK place minimig to allow access http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=52&products_id=610
PSU place minimig to allow access bypass the batteries
SOUND: generic junk http://www.dealextreme.com/details.dx/sku.4 / http://www.dealextreme.com/details.dx/sku.2185

other criteria:
- add a switchable buzzer+LED to emulate disk read as per article http://hackaday.com/2010/07/28/emulatin ... ppy-drive/


At the moment, I am having trouble finding information about the minimig output modes and ideal aspect ratio so that I can choose a screen. It seems that the minimig only outputs via VGA and that the VGA cable can be converted into RGB component cable connections with a little modification of a VGA cable as per this advice:
Quote:
VGA and Component video are essentially the same thing. If you pull
apart a VGA cable you will see that inside there is a RED, GREEN and a BLUE
whire inside. All VGA is is component with additional wires to control the monitor
from the computer. A VGA to Component adapter can easily be made simply by
splicing pins 1 and 6, 2 and 7 and 3 and 8 while shorting 4 and 5 as vsence (ground).
Each of those pairs in that order are; RED, GREEN and Blue.

Is this method correct/advisable? Any thoughts / comments?

... oh and hi ;)


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PostPosted: Fri Jan 14, 2011 8:50 pm 
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Location: A boring suburb of Chicago.
vapour wrote:
At the moment, I am having trouble finding information about the minimig output modes and ideal aspect ratio so that I can choose a screen. It seems that the minimig only outputs via VGA and that the VGA cable can be converted into RGB component cable connections with a little modification of a VGA cable as per this advice:
Quote:
VGA and Component video are essentially the same thing. If you pull
apart a VGA cable you will see that inside there is a RED, GREEN and a BLUE
whire inside. All VGA is is component with additional wires to control the monitor
from the computer. A VGA to Component adapter can easily be made simply by
splicing pins 1 and 6, 2 and 7 and 3 and 8 while shorting 4 and 5 as vsence (ground).
Each of those pairs in that order are; RED, GREEN and Blue.

Is this method correct/advisable? Any thoughts / comments?

... oh and hi ;)

Hello there!

The method you found is wrong. VGA and Component are NOT pin-compatible. VGA uses RGB (red green blue) while component uses YPbPr (Y=luma (brightness) plus sync, Pb=difference between luma and blue, Pr=difference between luma and red) They are two different ways of carrying a high-quality analog signal. However, you can convert from VGA to component (I don't have a link handy).

But I fail to see why VGA out would be a problem. Usually it's easier to find monitors that have VGA inputs than those with component inputs. As far as aspect ratio goes, I would think that the minimig would use 4:3 since it's an Amiga reimplementation, and widescreen TV's were nonexistent when the Amiga was popular. Depending on the screen size you were looking for, something like this 15" monitor could work: http://cgi.ebay.com/NEC-MultiSync-1560V-Black-15-LCD-Monitor-Screen-VGA-/400184104590?pt=Computer_Monitors&hash=item5d2cd4d68e This was just a randomly picked 15" VGA monitor from eBay, it may not be the best choice for modding into a laptop. (personally I'd think one of the older style 15" monitors with an external power brick would be nice, since you know that the monitor will work easily on DC voltage) I just picked 15" as a size, since it seems to be a fairly standard laptop size, obviously since you're making this you can make it whatever screen size you'd like. I see from the minimig Wikipedia page that it's nano-ITX-size, so you could easily pick a smaller monitor for a smaller overall laptop.

_________________
--John (and please call me John, it's really weird to be called by my username)
Fight MS Paint abominations! If you don't have a camera, go here, and pick something 3 megapixels or higher.


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PostPosted: Fri Jan 14, 2011 9:16 pm 
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Thanks for the timely response jdmlight, I am going out tomorrow to peruse my local surplus store and needed that info.

I was planning on implementing a smaller sized laptop, with a possible battery solution, so the common VGA monitors which run on mains wouldn't be the ideal solution.

I took a peek around for monitors of reasonable size (>= 10") which accept either VGA or mains and haven't had a lot of luck. It seems like the psone screen which can be modded to accept RGB input is my best bet as of yet but I was hoping for something other than that.

Here is a great solution I just scavenged up knowing that a 4:3 resolution is acceptable for the minimig (link). It'sa bit pricey so I'll check the surplus first obviously, but that has all the things on the checklist, VGA input, external powerbrick, decent size screen.

Another item I am searching for now is the current draw of the Minimig, seems hard to find. Once I have determined that I can begin to quantify power req's and a battery solution.


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PostPosted: Mon Oct 03, 2011 11:12 pm 
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Well update time!
...a lot of things happened but I came back to this project in the end.

This is the plan thus far, I found a cheaper LCD screen to use as well as an enclosure I liked:
Image

Green: LCD screen [link]
Blue: Keyboard [link]
Red: Minimig v1.1
Black: Battery9800mAh [link]
Grey: (2x)enclosure [link]

Not shown:
- mini trackball mouse, placement of external connectors and small speakers.

* I should mention that the model is constructed from each device's dimensions
* I have located a nicer, cleaner keyboard which is 2.5 millimeters wider than the case, it could be used and recessed into the top of the case along the edges. This is preferable as the keyboard stretches across the enclosure and is much thinner with nicer keys. [link]. I'll update the model tonight.


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PostPosted: Tue Oct 04, 2011 11:41 pm 
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Update as promised

Image

...The keyboard is a nice fit and it looks much more like a laptop keyboard would. I will have to make sure the enclosures match colours though, perhaps some accent painting on the inside.


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PostPosted: Tue Aug 21, 2012 10:59 pm 
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slow updates are slow, but yes it's not dead.

Am dropping the old enclosure as it was not suited to my needs, opting for a polulu cut enclosure from some thickness (probably 1/4") of acrylic. The enclosure will be designed to fit all the parts which I am modelling one at a time into solidworks with a pair of calipers and some patience. So far I have the minimig modeled and am going to do the monitor and batteries next.

A word of note on my choice of TFT monitor. the VGA does not work from the minimig in either NTSC or PAL modes, the driver board on the TV cannot handle these frequencies and some major distortion appears (below):
Image
Because of this I am going to attempt switching output frequency to 15khz via a jumper pin and use the RGB outputs to drive the display instead. This has worked for someone in a past project and saves me purchasing another display.

The trackball I had ordered was also much too cheap and it broke in my hands out of it's little case. As such I am looking into a different PS/2 solution.

I will be sure to post all my models when I am completed making them for others to use, they might save someone like me a lot of time with such a project.


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PostPosted: Thu Aug 23, 2012 8:27 pm 
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Models are being blackboxed from actual sizes, here I am gauging the size I will need for my enclosure in Solidworks. The input and output connections on the minimig were modelled with more care to allow accurate holesizes, etc.

Image

Estimated sizing will be >20 x ~25 cm x ~5 cm


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