Good morning,
I am looking for the correct 0.1 µF capacitors for the Apple-1, and I found a video showing an original Apple-1 motherboard.
The 0.1 µF capacitors on that motherboard look totally different from the ones usually used. Do you think they are original?
Thank you.
https://www.youtube.com/watch?v=A1kupEMjmF4
1:35
Those blue capacitors are multilayer ceramic, and were used on all of the Apple I boards from the second production run (with the "NTI" logo under Apple Computer 1). See the pictures here.
The production process for MLCCs produces rectangular "chips" with a thicker metal layer covering their ends. Nowadays every electronic device contains surface-mount MLCCs, but they are also available in leaded epoxy-dipped packages like the ones used here. Finding the exact same color and shape MLCC could still be a challenge, but I think there are details on this site about it, if you can find them.
I have a set of 0.1uF Bel capacitors for sale. Send me a private msg if interested
Thank you very much for the link. Do you think the Apple II motherboard revisions 3 and 4 use the same capacitors?
No, but they vary. My Apple II+ Rev.4 for example uses blue ones:
AppleIIRev4.jpg
Could you please suggest which 0.1 µF capacitors I can buy that look close to the originals? I checked a few online shops but couldn’t find any in the dark red color.
There are plenty on AliExpress that more or less look the part: https://www.aliexpress.com/item/1005003276169268.html
Modern multilayer ceramic capacitors are tiny, but for disk ones if they are 100nF and they are rated for 50V, they should be roughly the same physical size as the ones from the 70s.
they have diameter 5-8 mm and original one 10-12 mm
625010614_1641233837318732_2752946004550198887_n.jpg
you can see this original motherboard has blue capacitors
Whatever that is, it is not an "Original Apple I".
The yellow sockets, metal can 1404's, and oscillator trim capacitor were not part of the originals.
Looking though the Apple I registry you can see that most are with the large disk capacitors. There few with the blue multilayer ones and they look much better. I think the disk ones are too big and look ridiculous. In fact my 80-column card came with 5 of those, but I replaced them all with modern ones, because I hated how much they stick out and keep getting bent one way or the other until they break:
C80 CPL-3.jpg
It is even the "most expensive" Apple-1 to date.
https://www.rrauction.com/auctions/lot-detail/350902407346003-apple-1-computer-prototype-board-0-the-celebration-board-representing-the-earliest-known-fiberglass-apple-1-prototype/
That is the test board for the production fiberglass Apple-1 run. So think of it as Board #0. It was never sold to the public; it was given by Jobs to a friend and assembled using whatever they could get their hands on. Most parts are different, including the sockets from all other original Apple-1 boards.
Take a look at these. They are 5mm pitch, which means their diameter is around 10mm. They are rated for 1000V, but with modern capacitors that is the only reason to make them so large: https://www.aliexpress.com/item/1005008119400422.html
100nFCaps.png
IMG_3647.jpg
do you think it is to big?
It'll do the job, but I think it goes in the opposite direction in terms of being close to the original. I don't think I've ever seen an Apple I with polyester capacitors being used for decoupling.
Btw, you can still get blue multilayer ones by the pound from the scrap people.
Here is a current ad in Bulgaria I just saw this morning: https://bazar.bg/obiava-53882941/elektronna-skrap-kondenzatori
ScrapCaps.png
Do surplus components from Bulgaria always carry the aroma of hotel bedsheets and Chanel № 5?
You just hope that they don't have a smell, because if they do, it will not be of a 100 euros per ounce perfume!
Way too big. On the NTI boards the capacitors are much smaller.
3/4 of that can go directly to the junk bin as the legs are missing.
From the rest 1/2 of it can also go to junk as one leg is missing.
What is left is still questionable, not sure if it's worth the effort and postage even if it would be for free.
How many Apple I machines are you building?? You only need less than 20 good caps. The whole point of using scrap is to start with a large pile, handpick what you need and discard the rest.
Another important point to consider is that from the scrappers' point of view you are not really taking anything, since they are only concerned with the weight of the valuable metals. Thus a good relationship with scuppers can be very beneficial.
Depending on the type, there can be palladium in certain MLCCs, which explains why they were clipped by the scrappers.
These are called PME capacitors.
IMG_3698.jpg