Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: rja4096 on July 03, 2008, 08:51:32 AM
-
Hi, I managed to get a PSOne screen for 2 pounds from a car boot - its brand new. Any managed to hook it up through the compisite signal fo my A1200. Works great. My next step is to try connecting to the RGB out on the Amiga - for a better signal.
What next? - I have an A600 with hard disk, I might swap the hard disk for a CF card and try to make a A600 laptop.
I might remove the floppy drive as I don't use now I have PCMCIA - and fit rechargable batteries - does anyone know if running off 8 1.5 volt AA batteries for the 12v, and 3 1.5 volt AA batteries for the 5v (actually 4.5) would work. or do these voltages need to be exact?
Many Thanks, rick.
-
rechargeable batteries are actually 1.2V, so 4x 1.2 will work probably, but remember it will be fokkin hungry
-
I’ve tried tinkering with those PSone displays, and if im right, I think they need RGB and sync to operate - Check the hardwarebook for the pinout of the connector.
Don’t just use batteries!!!
As they discharge you're going to get all sorts of errors and malfunctions as the rails start to drop. At the very least, you need to have batteries with voltages above that of the rails which you intend to supply, then regulate the rails down with linear regulators. Some kind of alarm would be prudent to warn you when the cut-off point of the regulators has been reached (E.g. Their output starts to fall too).
I'd probably use an 18v battery pack and linear regulators to supply the necessary rails. Don’t forget - Amiga's also require a negative (-ve) supply rail, too.
A better and more energy efficient solution would be to use some kind of buck/boost converter system (Which I presume is used in laptops) to maintain the rails from a wide range of battery voltages; however that can be complicated and ready-built units of the sorts of current ratings you would require are expensive.
Hodgkinson.
EDIT: Amigas are just as sensitive to supply rail regulation as PC's, you know. +/- Half a volt can make a huge amount of difference.
-
a lithium ion battery pack for a laptop might be a good idea. if you can get an external charger for one.
lithiums hold a very steady voltage full charge to no. they also all have a builtin charge controller and will simply shut down when low on power. (most provide a signal to the laptop for charge level)
i think messing around with a regulated nicad pack or nimh would be worth it if you were building the whole thing from scratch. lithium bat packs can be gotten on ebay for a pretty decent price though.
-
@rja4096
You obviously have not seen my Black A600 with PSONE screen yet.
Click on My name here in Amiga.org...then view my Photo Album :-)
I bought 3 of these screens and made a Portable VJ Rig with the CD32/SX32 Pro. I sold part of that later and put one of the screens on my A600
-
Hodgkinson wrote:
A better and more energy efficient solution would be to use some kind of buck/boost converter system (Which I presume is used in laptops) to maintain the rails from a wide range of battery voltages; however that can be complicated and ready-built units of the sorts of current ratings you would require are expensive.
Most indeed are, but check out the offerings of this eBay shop: http://stores.ebay.com/Sure-Electronics_Prototype-PCBs
Specifically you would need their MC34063 Based Switching Regulator Adapter, Step-Down item.
It's not the first time I bought stuff from this shop, and would recommend them, though I haven't tried this particular power supply.
Granted, it's only step-down and you'd have to use batteries with a high enough voltage to ensure that even when discharging, they keep a stable voltage as long as possible (you need at least 2V more than your required output). On the web there is info about a white LED hack for the PSOne screen to reduce power consumption.
Cheers!
Edwin
-
That's the kinda thing I was thinking of. Mind you, 0.5A max doesn't leave much room for add-ons, unless you powered different sections from its own converter, which is inherently risky. Oh, and a -ve rail still needs to be generated - I think there's switching converter modules available that will produce negative voltages, too.
BTW, A Switching regulator, or step-down converter, as opposed to a linear regulator, should yield better battery life and efficiency, since rather than just *dropping* the voltage and dissipating the energy as heat (V*I=W), switching regulators actually "transform" (Or at least use PWM) it as such, meaning that with fully charged batteries, you should, in theory and with 100% efficiency, be dragging less current from the batteries than the combined output of the switching regulators. :-D
-
Very few things are 100% efficient, certainly not DC2DC conversion.
I have a project like this sitting on a shelf. I bought a surplus DC2DC laptop supply years ago. I supply it with something like 18 volts and it supplies 5, and +/- 12 volts. It should not be too hard to find defunct laptop and scavenge it's converter.
I have not bought a screen yet, but have looked with interest at the PS1 screen. Please upload some pics of workbench on yours in composite mode. If you get RGB working, definiely share the pinouts and modifications.
Leirbag has a cool system, you should see the pics.
-
I strongly suggest a pico-PSU and a +12V laptop battery. The battery must source 5A at minimum for operate a A600.
It transform the +12V in +5 and -12V (among other not-required tensions). Prefer a 60W pico-PSU for use with your A600.
The +12V line accepts the 10.3~12.3V range for normal operation (remember: the pico unit don't regulate the +12V rail, that is simply bypassed).
-
When I tried the PSOne screen that I got, although it did work and was easily readable when operating in the low res mode of WB, high res became somewhat harder to read (You had to have a prior insight as to what the buttons said).
Also, for some reason mine had horizontal lines across the image and the built-in speakers didn't work. But I've got a feeling that it might be because everything else that I bought from the bloke was faulty, too. :madashell:
-
Hi Fogot to say, I was amazed to see interlace mode was completely flicker free
-
What is the native resolution of the PSOne screen? Is it 640x480, or less?
-
Umm, on powering by batteries but stepping down through some kind of step down circuitory, I guess I'd need something like at least 26 volts, to drop down to the -12 and +12 (difference of 24?). Also I'd need two drop down circuits, as I'd also need to drop down to the 5 volts. - which would share the same common ground(zero)?
Is this correct? Thanks.
-
Don't forget, regulators usually need an overhead of about a volt or two for operation, and you need to allow for the batteries to discharge, so I'd say at least 18 volts of supply for a decent period of operation - Then step this down to the required +5v and +12v.
For the -12v rail, you could use another pack of batteries but that would be really overkill, as (If im right) it’s only used for some of the ports on the back. I’m sure DC-DC converters are available that produce a negative rail from a positive rail, so one of them might be best to supply the -12v.
Everything shares the same ground rail.