Apple I Fairchild voltage regulator

You can go through all the Apple I machines in the registry and take a look, but from a quick glance it looks like most of them if not all used the National Semiconductor one.

Most of the regulators on the Apple 1 board are National Semiconductor but there is a UA7812UC on most of the boards I have seen instead of the LM340-12 as shown on the label. 

 

Regulator.png

In post #1, 'sergey2b' wrote:

" Hello, could you please let me know if there is any information about did the Apple I use a Fairchild voltage regulator ? "

Uncle Bernie comments:

I can't give you a competent answer about the original Apple-1, but if your question boils down to the Apple-1 clone you may be building, the Fairchild UA323K works fine in it. Most of my kits had those after the ST LM323K became unobtainium and Mouser / Digikey rang up prices around $68 (each !) for the TI product.

- Uncle Bernie

The original Apple-1 used a National Semiconductor LM323K for the +5V.    If you want to be authentic.

The other regulators vary depending on which batch they were wave soldered.

In post#6, 'Corey986' wrote:

" The original Apple-1 used a National Semiconductor LM323K for the +5V.    If you want to be authentic. "

Uncle Bernie has a  question:

Did all the National Semiconductor LM323K in the Apple-1 originals have  a"golden base" ?

Just asking because I've got word somebody has  gone as far as buying a laser welder to be able to make 'fake' golden base LM323K.

I happen to have a bunch of other National Semiconductor 5V golden base regulators - some with 1976 date codes - but these are only rated for 1.5A which is just barely enough to run an Apple-1 with the ACI. No further power consumers allowed in this case. But there is a trick with a bypass resistor on the backside of the PCB to allow for somewhat higher loads, but not for the full 3A.

Would like to see your comments on the "golden base" topic, because it's tedious to make 'fake' ones and if there are original Apple-1 with no "golden base" LM323K, then we could avoid these extra efforts.

- Uncle Bernie

UncleBernie wrote:

...

Did all the National Semiconductor LM323K in the Apple-1 originals have  a"golden base" ?

Just asking because I've got word somebody has  gone as far as buying a laser welder to be able to make 'fake' golden base LM323K.

...

Would like to see your comments on the "golden base" topic, because it's tedious to make 'fake' ones and if there are original Apple-1 with no "golden base" LM323K, then we could avoid these extra efforts.

Here is a topic from 2012 about that: https://www.applefritter.com/content/recreating-gold-lm323k-apple-1

Yes, all original Apple-1 boards had gold LM323K when shipped.   On the registry, you can see some have had them replaced with ordinary LM323K, most likley when they died or to replace one that was stripped off.

Why would someone need a laser welder to make fake gold LM323K regulators?   Sounds like an excuse I use with my wife to buy a tool I really want to play with but really can't justify.

Below is a picture of a replica LM323K I made for one of my Mimeo's back in 2012/2013.  This is what it looked like back then.  Today, it has a nice patina to it, close to a 50-year-old original one, since I run this replica pretty often. I have several original regulators now, and you'd be hard-pressed to tell which was original and which wasn't without a microscope.   You really can't make them 100%, but my replicas look 99.9%

Before anyone asks, I am not selling the replicas or originals.  I keep the originals gold LM323K  for original Apple-1 boards that have "lost" their gold LM323K over time.  And yes, I have offered one to the Computer History Museum and told them to just place it in the original place, don't bother soldering, but they don't want to touch their Apple-1 on display.

replica_regualtor_2013.jpg

Surprised no one is actively making them... It's actually surprisingly easy.  First, the gold bottom is simple.  I used a low-voltage gold-plated pen (<4V).  Took me a few tries to get the right type of gold to match an original. I started with 18K and settled on 24K, but I had all this stuff from repairing 6502 legs.   

For the logo, you remove the old logo mechanically.  For the printing of the logo, I used a high-resolution laser printer that printed the logo in reverse onto wax paper.  You need the right kind of laser printer with a straighter path that won't mess up the toner as it's printed on the wax paper.  This will not work with an inkJet or some of the more eco-friendly laser printers.  It needs real plastic-based toner.

Then, using a temperature-controlled clothes iron or wood burner with a flat round head, don't remember the temp as I haven't made a replica 323K in about 13 years, but just enough to remelt the toner with the logo onto the top of the regulator from the wax paper you secured in place for the transfer.  You have to be careful you don't move or smudge the logo as you peel the wax paper after the transfer.   You need steady hands, and if you mess it up, simply mechanically remove the logo and start again.

Over time, the shine of the regulator's top case starts to age.  Heat cycles help, and it looks pretty darn good.   

Note: The regulator case never gets hot enough to remelt the toner, and you can clean it with ISP without any issues.

I also gold-plated all the LM323K for my three replicas. It was surprisingly easy, using a plating pen and some electrolyte.

As recommended by the electrolyte manufacturer, I did apply a palladium barrier layer beforehand. But stainless steel generally works without it too.

The lettering was done by using a toner transfer method.

IMG_1227.jpg

      

Screenshot 2026-04-30 133239.jpg

Maybe this helps to get the logo and the date code and the "ageing" effects for the "fakes" right:

LM309K_small.jpg