I fitted my Amiga 500 into a tower and used a conventional power supply. Never had any issues. Mind you, this was done 20 years ago and my Amiga is still in the loft 😂
I remember when I was debugging a early PSU on a resistive load and saw 400hz spikes. Took me ages to figure out it was coming from the fan I was using to cool the dummy load :)
I've just watched a couple minutes and LOVE the idea of this. I have too many random PSU's laying around because I want to run my 520ST one day and then one of my Amigas the next. Maybe I could adapt one of the PSU's I built for my Amigas to the 520ST....that might be easier since the Amiga PSU already has all the needed voltages....hmmmm
@@thetechnoshed actually, I can use my 520ST PSU as it has all the voltages needed. I'll take an old Amiga PSU cord with the male plug and wire it into a DIN connector that will mate up to the port on the 520ST PSU.
I doubt it's a factor, but just double check the power ratings. Whilst we don't have spinning discs very much any more, we do have accelerators which need an amp or two more than a baseline ST without internal floppy would have done back in 1985!
With your British standard plug (even visibly connected while measuring continuity), why would you need to solder an in-line fuse to the live side? That seemed a whole lot redundant to me.
I did mention this in the video. It is a bit belt and braces, true, but technically the fuse in the plug is there to protect the cable. That's a 13A cable. It's not impossible for someone to unwittingly put a higher fuse in later.
Nice work! And I absolutely agree with you that Amiga music is crap. I "upgraded" my C64 to an A500 in 1989, and everything was better except for the audio (and the demo scene, c64 scene > amiga scene). 8 bit tracker music, what can I say. I'm glad that's not really a thing anymore. c64 = 1MHz DAC (arguably), Amiga = 16KHz DAC (because of Paula DMA). How does the boost converter provide -12V though? In is +12V and GND I presume? So you boost that to something like +24V and GND, but how do you bias that to make it -12V +12V, while preserving +5V and GND? Using op amps? And what's the chopping frequency of the switch? I think a couple of low noise caps with different order of magnitude Farads to GND should be fine to tame ripple. The DAC on the Amiga is garbage anyway. I'm not really proficient in electronics, but the 25Hz you see, couldn't that just be the -1 harmonic of 50Hz? You can get subharmonics from nonlinear stuff like switching. And 25Hz noise on the rail could definitely mess with the DAC depending on the magnitude. Could give you noise at 50Hz, 75Hz, 100Hz etc. In the end though, lipstick on a pig. I bet your solution is empirically better than what a bog standard A500 can do with the Commodore PSU, audio wise. Sorry for the essay! This is just a topic I love to geek about. :D
The boost converter is just a low cost module off eBay. I don’t know how it goes about generating the negative voltage, but since it’s obviously switching something, I was programmed to worry about noise. You’re right the 25Hz is likely directly relayed to mains. It would not surprise me one bit if it turned out to be the lighting in the shed!
I fitted my Amiga 500 into a tower and used a conventional power supply. Never had any issues. Mind you, this was done 20 years ago and my Amiga is still in the loft 😂
as usual a great video. thanks David.
Many thanks! I don’t know how whacking an eBay module into a power supply ended up 38m long and taking a week, however!
I remember when I was debugging a early PSU on a resistive load and saw 400hz spikes. Took me ages to figure out it was coming from the fan I was using to cool the dummy load :)
I fall for it *every* *single* *time*!
I've just watched a couple minutes and LOVE the idea of this. I have too many random PSU's laying around because I want to run my 520ST one day and then one of my Amigas the next. Maybe I could adapt one of the PSU's I built for my Amigas to the 520ST....that might be easier since the Amiga PSU already has all the needed voltages....hmmmm
Just have to find a female version of the Amiga connector. Or perhaps splice in a middle man which is more readily available?
@@thetechnoshed actually, I can use my 520ST PSU as it has all the voltages needed. I'll take an old Amiga PSU cord with the male plug and wire it into a DIN connector that will mate up to the port on the 520ST PSU.
I doubt it's a factor, but just double check the power ratings. Whilst we don't have spinning discs very much any more, we do have accelerators which need an amp or two more than a baseline ST without internal floppy would have done back in 1985!
With your British standard plug (even visibly connected while measuring continuity), why would you need to solder an in-line fuse to the live side? That seemed a whole lot redundant to me.
I did mention this in the video. It is a bit belt and braces, true, but technically the fuse in the plug is there to protect the cable. That's a 13A cable. It's not impossible for someone to unwittingly put a higher fuse in later.
Nice work! And I absolutely agree with you that Amiga music is crap. I "upgraded" my C64 to an A500 in 1989, and everything was better except for the audio (and the demo scene, c64 scene > amiga scene). 8 bit tracker music, what can I say. I'm glad that's not really a thing anymore. c64 = 1MHz DAC (arguably), Amiga = 16KHz DAC (because of Paula DMA).
How does the boost converter provide -12V though? In is +12V and GND I presume? So you boost that to something like +24V and GND, but how do you bias that to make it -12V +12V, while preserving +5V and GND? Using op amps? And what's the chopping frequency of the switch? I think a couple of low noise caps with different order of magnitude Farads to GND should be fine to tame ripple. The DAC on the Amiga is garbage anyway.
I'm not really proficient in electronics, but the 25Hz you see, couldn't that just be the -1 harmonic of 50Hz? You can get subharmonics from nonlinear stuff like switching. And 25Hz noise on the rail could definitely mess with the DAC depending on the magnitude. Could give you noise at 50Hz, 75Hz, 100Hz etc. In the end though, lipstick on a pig. I bet your solution is empirically better than what a bog standard A500 can do with the Commodore PSU, audio wise.
Sorry for the essay! This is just a topic I love to geek about. :D
The boost converter is just a low cost module off eBay. I don’t know how it goes about generating the negative voltage, but since it’s obviously switching something, I was programmed to worry about noise. You’re right the 25Hz is likely directly relayed to mains. It would not surprise me one bit if it turned out to be the lighting in the shed!