Commodore 128 tower project continued!

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tokyoracer wrote:
Scandoubler/flicker fixer? Do they exist for the C128?

Composite (40 column) to SVGA - very common, I bought this.

RGBi (80 column) to SVGA doesn't exist, one has to be modified. I bought this and modified it myself. The modification is quite simple. This is a scandoubler, but not a flicker fixer. The VDC does indeed have interlace modes, but almost no software supports it. I have not tested mine for interlace yet, but I suspect there will still be flicker.

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The same tricks apply for the 1581 as the Amiga concerning the drive mechanisms. You can modify a PC drive to be Amiga/1581 compatible and it will mount neatly in the front panel.

Mine is done like that, I'm using a modified PC mechanism.

In that sense, yes you are correct. I was thinking about getting an Amiga 2000 drive, but maybe a PC drive would be better. Did you reference anything for your project? An Aminet hack maybe?

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One more pic:



Running Geos128.

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Get DC to pin 2 and RDY to pin 34 and make the drive answer to DS0. ;-) The Brazilian dudes figured out a way to cheat the RDY signal by jumpering pin 30 to pin 34 on the drive, but I haven't tried that myself.

Hmm.. I might be pestering you here soon for info  :-D

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Fester wrote:
Yes, your project looks really good! Congratulations.

Thanks!!  :-D

I await delivery of orders from Mouser, Jameco and the composite-VGA adapter from China to continue to the next step. With any luck I will be going full steam into stage 2 this weekend. The expansion port extension cable will be a {bleep}...

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I couldn't help thinking the power supply was only half done, so I spent the night tweaking it. The 9VAC would shut off if the ATX power supply switch turned off, but not if the case switch only was used. I decided a relay would be needed. Here is what I came up with.



A relay alone would have been easier, but I decided I wanted an indicator LED. Easier said than done when output is 9VAC. A bridged rectifier was needed. Below is the relay mounted to the power supply.



The relay coil is picked up from the ATX 5VDC from the connector shown in the picture. I will probably eventually wire that directly to the ATX board.

So far it passes testing and works great, even the LED lights!  :-o 9VAC turns off with the regular case power switch. That is more like it.

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B00tDisk wrote:
Now does the ATX switch behave like it does in an ATX mobo system - eg one tap shuts down from the system or press and hold to "sleep" or what? :-)

No, it actually behaves like an AT system. Either completely on or completely off.

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Maybe it would work ok with just the LED and a resistor - Even on AC (The LED is a diode in itself)? OK, maybe the led would flash at 50Hz  , but this shouldn't be much of a problem.

I thought about that, but I figured making a bridge rectifier should be easy enough and it was. I even added a capacitor to smooth out the pulse. The led looks rock solid when lite. BTW we have 60hz @ ~120V on this side of the pond.

EDIT: What's the relay switching? The 9VAC side or the mains side of the transformer? If im right in saying it’s a reed relay; they aren’t normally designed to switch much current. Maybe a 100mA or so at most, and not usually mains either.

It is indeed a reed relay and it is on the 9VAC side, not the main. I could have put it on the main side, it is rated for 1A at 125V. C128 brick power supplies are rated for 1A for 9VAC, so this can easily handle it.

The step down transformer I am using for 9VAC is freaking huge, only because it was the best/cheapest I could find for this project in a quick search. It is completely and entirely overkill for this application. It is a multi-tap transformer with only the 9VAC being used and it is rated at like 2A on the main side. It was cheap, it cost me about $6 + shipping. The main electronics houses here didn't have anything even close in stock.

EDIT2: Hey, what about having a high current relay, controlled from the ATX PSU, switching the mains side of the transformer? That way, you can save on the energy costs of having the transformer powered up all the time, and you can use a neon indicator (W. resistor of course) on the mains side rather than trying to use a LED.

I was originally thinking about putting this relay on the main side, but I decided I didn't want exposed 120V inside the case. Yeah I probably could have mounted this board in the PS itself, but I didn't feel comfortable doing that. The transformer will be energized all the time, but how much loss can it really have idle? It can't be much. I can always still switch off the ATX switch, which will kill it too. It picks up power after the ATX switch.

Thanks for the great comments and suggestions! :-)

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redrumloa wrote:

It is indeed a reed relay and it is on the 9VAC side, not the main. I could have put it on the main side, it is rated for 1A at 125V. C128 brick power supplies are rated for 1A for 9VAC, so this can easily handle it.
 

Doh! Looks like the reed relay was a bad choice, the coil failed. I probably should have put a current limiting resistor before the coil. Back to Radio shack..

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Hodgkinson wrote:
I'd still advise a nice chunky standard relay :rtfm:

Maybe, but I hate the chunkiness..

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tokyoracer wrote:
Cripes, it has an OS!? Will a HD connect to a 128?

Not easy, but yes. For pure speed I will have a 16MB RamLink internal, which is essentially a 16MB hard drive and the fastest mass storage option for 8bit commies.

I will also be installing a X86 SBC (single board computer) internally as a slave to run 64HDD. That will give me a hard drive as big as I wish and acts like a hard drive. At first I will just be using a 4GB Compact Flash, but I may add a large IDE hard drive (200GB?) and CD-ROM eventually.

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This is a nice project...

Now that's just cool 8-)

Thanks guys, I'm quite happy so far  :-D

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trekiej wrote:
What is the X86 SBC that you will be using?
Just currios.
 

This one :-)

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The 9VAC relay board is fixed!! A more heavy duty PC relay is now used.



Here's a pic of the composite to VGA converter getting mounted.

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I've been thinking to install one of those in my A2500. I don't know exactly yet what I'm going to use it for, but it'll be "just because I can".

Yup, if you find one like this it would go right into an ISA slot. No communication internally to the Amiga, but you can connect via serial null modem. Maybe install a stripped down Linux, which you could access via terminal.

Quote:
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I may add a large IDE hard drive (200GB?)

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Wow, that way you can have 6 copies of all C64/C128 software that's ever been made on a single harddisk!

I can have a complete library of Commodore software at my fingers, correct. I can also have a SID collection, MOD collection, graphic library (Koala, JPG, MacPaint, Ipaint etc) and anything else I can think of  :-D Geos software can get pretty beefy.

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Hodgkinson wrote:
> A more heavy duty PC relay is now used.

;-)
Hodgkinson.

Yeah, yeah, yeah, I never claimed to be an electronics guru :-P You can certainly hear the computer turn off and on now. Clunk! Clunk!