Certified idea for a repairable heavy duty power supply

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steveday72
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Re: Certified idea for a repairable heavy duty power supply

Post by steveday72 » Tue Jun 20, 2017 7:54 am

I don't know if anything will eventually come of it, but I've been gathering parts for a 50/60hz selectable PSU over the past 2-3 years.

It will take a laptop DC input, convert that to what it needs via DC-DC modules. For the 9VAC output it will use an EGS002 pure sine wave module connected to an H-bridge drive, which will pass through a low-voltage 10A isolating transformer that I bought last week. All other outputs (5V for 64, 5V for fdd, 12V for fdd) will be generated via isolated DC-DC modules (like the Lucent ones - which you can buy surplus now and save $$).

I think I've just about got everything for the project now, but I'm too sick/injured to work on it (all I am able to do is read in bed 98% of the time ... (it's not good as some might think) 😬



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Oge_user
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Re: Certified idea for a repairable heavy duty power supply

Post by Oge_user » Sun Jun 25, 2017 4:12 pm

Some time ago I was researching for the way to operate any machine, regardlessly of the Assy version, using fully regulated current without even touching the internal motherboard.

I was close to find a suitable method and it worked up to the point that a partially defective Breadbin motherboard, which had intermittent startup, worked perfectly everytime. I gave up helping with innovations though, not worth the sacrifice anymore.

The EGS002 seems to be a valid inverter and it may be tuned up with external filtering. Just make sure that it handles at least 1200mA without issues or peaks.
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Gyro Gearloose
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Re: Certified idea for a repairable heavy duty power supply

Post by Gyro Gearloose » Mon Jun 26, 2017 4:07 pm

People sure seem to love complex solutions to simple problems...
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.

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Re: Certified idea for a repairable heavy duty power supply

Post by Ready. » Fri Jan 19, 2018 8:20 am

In the end having a PSU with just the transformer to have it certified did not work out. I will instead stick to the design of a transformer at 50/60Hz as described here:
http://danieleredivo78.wixsite.com/c64psu
so far I made 7-8 units delivering up to 3.5A at 5V. The nice thing is that using DC-DC converters provide a much lower ripple than AC-DC converters.
For ex Meanwell RS-15~5 datasheet states a ripple of 80mV https://www.tme.eu/it/Document/510a351c ... 20FULL.pdf
which is much more than what I get from using XL4015 DC-DC board with added output caps, I get 35 mV at 3A.

I have now developed a 5A from 5V version of my PSU using two parallel XL4015, in load sharing mode, so they always share the same current. Even there the ripple is around 35-40mV at 5A. So quite nice.

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Re: Certified idea for a repairable heavy duty power supply

Post by steveday72 » Tue May 15, 2018 4:20 am

Gyro Gearloose wrote:
Mon Jun 26, 2017 4:07 pm
People sure seem to love complex solutions to simple problems...
If you know of a simple way to generate 50Hz power supply from a 60Hz powerline I'd love to hear it.

Some programs do depend upon the CIA RTC/TOD clock for accurate timings. (I'm sure you know the CIA clock gets its timebase from the mains power ... apart from the SX-64, which is always 60Hz even on PAL versions).

The isolation between the 5V DC & 9V AC lines is needed because the C64 power switch only toggles the 5V line. If the two are not isolated then the 9V will feedback through the SID chip and find a way to ground, potentially damaging a 5V IC in the process.

Yes it's a very complicated design, but I'd rather not modify every C64 before I connect them to it. Plus it will give me enough protected outputs to power multiple devices - which beats having multiple old timebombs under the desk, just waiting for the moment to zap valuable hardware!

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Gyro Gearloose
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Re: Certified idea for a repairable heavy duty power supply

Post by Gyro Gearloose » Tue May 15, 2018 8:16 am

The SX-64 uses a dedicated ASIC to generate a 60Hz signal. You don't need an entire power supply just to generate a signal.

"The isolation between the 5V DC & 9V AC lines is needed because the C64 power switch only toggles the 5V line."

I don't know what that means. One side of the 9VAC is routed through the power switch. There is no power inside the 64 when the switch is OFF if that's what you were implying.

"I'd rather not modify every C64 before I connect them to it. "

That wasn't part of your original post. How was I supposed to know that? You were talking about "certifying" a repairable power supply. To me, that seemed like using a tactical nuke to kill a housefly. Sure, the fly is dead after, but...

"multiple old timebombs under the desk, just waiting for the moment to zap valuable hardware!"

That's a fair point.

"If you know of a simple way to generate 50Hz power supply from a 60Hz powerline I'd love to hear it."

I do. And once my health improves I'll do it.
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.

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