Uncle Bernie's Power Supply Mod

In post #1, 'retroplace_1' wrote:

"You must not use this modified power supply if your Apple-1 has been modified to work with "direct feed" (a mod published by Bernie) that allows you to use a standard PT-65B power supply..."

Uncle Bernie comments:

Let me clarify that I ("Uncle Bernie") NEVER have  "officially released" to the public the complete instructions I wrote for my "Direct Feed" mod to the Apple-1. One three beta testers got those, under the condition to keep them confidential. The story is a bit involved, but in the end I decided not to publish these instructions. See " The end of 'Direct Feed' " in the relevant thread:

https://www.applefritter.com/content/running-apple-1-one-cheap-switchmode-psu

Despite none of my own Apple-1 using 'Direct Feed' ever blew up, and they were running 24/7 for more than a year, I can't recommend 'Direct Feed' anymore. Despite of the painstakingly selected and qualified regulators which, according to the results of my lab experiments, could take the peculiar conditions under 'Direct Feed' without drawing any excess current, I found after the retirement of my burn-in rigs that one of the LM323K regulators in my seven 'Direct Feed' Apple-1 had died (but without causing any further damage, the Apple-1 still worked, with the dead regulator, as long as it had the 'Direct Feed' wires, and the dead regulator was only discovered after 'Direct Feed' was removed). Unlike the other LM323K, this regulator was not made by ST, so it never was qualified in my lab to be run under 'Direct Feed' conditions. Seems that I just had taken that risk when I scrambled to make more burn-in rigs from my older builds. Which was a mistake. That LM323K died. Lesson learned. The risk was known and taken. Still, another nail in the coffin of 'Direct Feed'. Qualifying these regulators for the method is just too involved for the typical hobbyist. (Don't try it yourself !)

Now, if you ever read the above thread, you may have seen post #6 by 'Corey986' (who is the world's first and foremost expert on original Apple-1, the auction houses hire him to certify them as 'originals'). He wrote:

"I would actually use a supply with 9V, -9V, 18V,-18V and run them across the normal regulators on the Apple-1 board, so that the ACI got -18V."

His concerns about the ACI were unwarranted, as that myth that the (original) ACI works best with certain negative voltages has been debunked during my improvement work on the ACI, which now is finished, and yielded a perfect ACI that works very well (see relevant threads on Applefritter), and the four voltages he suggested are not needed, they can be reduced to three, as the Apple-1 makes its -5V supply from the output of its -12V regulator. This leaves three voltages needed, +8V, +15V, and -15V, or slightly higher. (The numbers given provide just enough headroom for the on-board regulators on the unmodified, standard, Apple-1).

Alas, such a switchmode power supply making +8V, +15V and -15V does not exist as a standard catalog item. So I ventured into developing a mod for the popular (and cheap) "Mean Well" PT-65B (and similar ones, like the PT-45B, RT-50B and RT-65B). The beta testing phase for the PT-65B and PT-45B mod is now complete (it has been greatly delayed by trouble one of my U.S. based beta testers had with his attempt, which turned out to have been caused by Chinese scammers who sold him a defective PT-45B on Amazon they obviously had fished out of the electronics junk recycling stream and then  'repaired' it such that the 'new' 7905 regulator they put in developed a package delamination and first got intermittent, and then ceased to work at all). Another lesson learned. He did not even save money on the Amazon price vs. the price the official distributors like Mouser or Jameco ring up, all he saved over Mouser was the 'free shipping' (from China, of course), which took weeks. Mouser orders to U.S. destinations typically arrive in 3 days.

Armin is the third beta tester for my 'PT-45B/65B modding instructions' and he is reliable because he follows these instructions exactly as prescribed, being an official business, and not just some hobbyist, who might cut corners and use other components than those prescribed.

So if you want one of these switchmode power supplies modified to run an Apple-1 in lieu of the transformers, go for Armin's offer !

- This takes the risk out that some hobbyist electrocutes himself when working on modding the PT-65B / PT-45B.

Further advantages:

- Your Apple-1 will run much cooler compared to the use of transformers.

- It will also be lighter and more robust against g-shocks (Transformers are heavier)

- It will run from any household power outlet anywhere in the world. These "Mean Well" products are true "World Power Supplies" that will work with any line voltage from 100 Vac to 230 Vac, and any usual frequency (50 Hz or 60Hz). You could also run them from a solar panel with a DC voltage in that range.

CONCLUSION

As far as I am concerned, I'm now running all my fourteen Apple-1 with such  modded 'Mean Well' power supplies, and it's a really cool and efficient solution, which also saves energy. Wish I would have had that power supply solution earlier.

- Uncle Bernie