Notices by Bernie (codewiz@mstdn.io), page 6

@dnc All right, which vegan cheeses are actually good? I keep buying different brands and styles, but none of them comes close to the real thing.

Crave for good cheese is the main issue preventing me from upgrading from #vegetarian to #vegan.

@dan I've already tested that sodium carbonate to rewash some yellowed kitchen and bathroom towels, but they still look the same.

Guess I'll ask for a refund 😉

@jxself And where would I get these test strips from?

As you just saw, I'm totally clueless and confusing "sodium peroxide" with "sodium percarbonate".

Ideally I'd just get a can of Mom's Old-Fashioned Retrobrighting Lotion (made with 10% more love than the next leading brand!)

Before realizing that sodium percarbonate was actually what I was supposed to use, I started a small AB-test in my UV chamber using plenty of sodium carbonate.

After spending about 12 hours dipped in the solution, the '+' key (treatment) is visibly less yellow than the '-' key (control).

Despite using the wrong #chemistry, my first #retrobrighting experiment didn't completely fail. Can anyone explain this surprising result?

#retrocomputing #vintagecomputing

@pixel Which UV lights did you buy? I have no idea how to measure the luminosity and the exact wavelength of my UV leds. I just picked these because they were cheap and powered via USB.

@pixel Ah, there's also a powdered variant which contains only two ingredients: disodium carbonate and sodium percarbonate, though they don't specify the quantities:
https://www.amazon.com/OxiClean-Versatile-Stain-Remover-7-22/dp/B005GI8UOO

Before I thought all laundry detergents were more or less the same, now I know that even the same brand name can have totally different chemical compositions 🙃

@pixel I happen to have a big bottle of OxiClean, but sodium percarbonate isn't listed among the ingredients, only "sodium laureth sulfate", "sodium bicarbonate" and "sodium formate" 🤔

@jxself I find your reasoning more persuasive than any of the LLMs that were consulted so far:
https://mstdn.io/@codewiz/113711484285996319

Your formula gives 369g/L, a bit more than Copilot's 275g/L and ChatGPT's 286g/L.

But where is the mistake in their process? The calculations and the atomic weights look correct.

@El_Jefe Both ChatGPT and Copilot (aka Bing Chat?) claim that you need ~280g of percarbonate to make a single liter of 12% peroxide.

If only we could find an expert human to check their reasoning... 🙃

But I suspect what was actually needed was sodium *PER*carbonate! 😫
https://en.wikipedia.org/wiki/Sodium_percarbonate

Wikipedia confirms that, in water, percarbonate decomposes into hydrogen peroxide. Which is why it works the same for #retrobrighting.

But I don't have any percarbonate at home, and it won't arrive before Dec 29 either.

Moreover, how much would I need to get the equivalent of 12% peroxide? Now I regret not paying enough attention in #chemistry classes! ⚗️

So I decided to try an alternative: sodium carbonate. Pure and natural since 1874... and dirt cheap at $0.10 per ounce!

I'm no chemist. Until yesterday, I didn't even realize that washing soda isn't the same of baking soda (sodium *BI*carbonate).

#retrobrighting #retrocomputing #chemistry

Many #retrobrighting videos dip the plastic to be treated in concentrated hydrogen peroxide, or coat it with hair bleaching cream, which may contain other chemicals.

But 12% peroxide is kinda expensive, and I couldn't find any in nearby stores. The fastest delivery I could find wouldn't arrive in time for Santa to admire my first retrobrighted keyboard.

@jxself Hang on, I'm writing another of those long threads :-)

This cheap PC keyboard will go first to test the effectiveness of my #retrobrighting process.

The very first step consists in a bath in dish soap and hot water. This should prevent grease and other dirt from blocking the UV light and the ozone.

While I was at it, I also threw in the PCB, just to see if my soap is safe for electronics.

Then I rinsed everything with fresh water and wiped with 70% isopropyl, which didn't seem to disturb the key engravings.

#retrocomputing #vintagecomputing

If you followed my A3000 restoration threads, you can easily guess which yellowed plastic I need to retrobright :amiga:
https://mstdn.io/@codewiz/113586277421694238

After watching several videos on #retrobrighting techniques, I started a couple of small-scale experiments to see if my setup works.

This year's Christmas decorations will shine in UV light! 😎

#retrocomputing #vintagecomputing

@trebroNdotnet I had the same question about D190 last night on Discord, and cdhooper enlightened me:

"That is a bit confusing at first. What is happening here is that the diode, at the input to D191, is generating about 5.6V (assuming a vdrop of 0.6V due to the 1N4148 at D190). Then, D191 drops that 5.6V by 0.6V to feed 5V into RP5C01 pin 18. So it's a clever trick to avoid the voltage drop that sourcing voltage through a diode normally incurs."

@idiot I believe AmigaOS reads the RTC only once at boot, as part of the standard Startup-Sequence.

Just to be sure, I'll check that there's no activity on the RTCR and RTCW pins at any other time.

@idiot Yes, but wouldn't the clock keep running on battery power if I pull the diodes?

My concern is that the Ricoh data lines would then be driven at battery levels, which will fall below 3V when as the battery discharges.

@globalc Thank you for asking around. I think I'm pulling it off on my own! See my updates from yesterday and today.