Archive for November, 2009

Apple 1 Replica Project Restarted #8

Monday, November 16th, 2009

Quick update on major areas.

PCB:

First pass of the following layers complete.
bottom copper
top copper
top silk

Up next:
Top solder mask which has some unusual features.

Pending:
Second and then third passes through each layer (these should go much more quickly than the initial pass did)
PCB vendor DFM (design for manufacturing) check
Net list check against schematics
Rounding off trace corners
Final Pass
Final DFM check
Final Net list check

Parts:

Some parts have been received
Others on order
Still determining best vendor for several key parts.

Example of what goes on when sourcing parts. I spent several hours yesterday reviewing the board edge connector and evaluating sources. If I was doing a new design I would just pick an appropriate part and layout the board to suit. In the case of a replica you need to determine the specifications of the part, find the part that fits the specs and finally find a source.

Overall Costs:

Note that some rough estimates on PCB cost indicate that the gold finger edge on the board will raise PCB cost more than I initially thought. Costs continue to look higher than the Apple II due to to PCB, more expensive obsolete parts than the A2, and the power supply. The two transformers alone cost over $40 for a single Apple 1.

Apple 1 Replica Project Restarted #7

Wednesday, November 11th, 2009

silk-example
example of progress on the silk screen (in yellow) overlaid over an photo of an actual apple 1.

Apple 1 Replica Project Restarted #6

Friday, November 6th, 2009

Work is moving forward on the silk screen layer. I was hoping that I could directly leverage fonts created for the Apple II rev 0 replica. The Apple 1 fonts are different enough from the Apple II fonts, that I am not satisfied with the default results of just porting the A2 fonts over. Therefore I’m working on improving the match with the original Apple 1 fonts. One other challenging aspect of the silk screen is my CAD program doesn’t support proportional character spacing. This is going to cause me some extra work in order to get the character spacing right, as it did on the Apple II rev 0.

With the exception of the gold finger connector, which hasn’t been added, the copper layers are pretty good right now, probably good enough for most people. However, I can see some areas, particularly on the front of the PCB that I’ll revisit once the silk screen has had a first pass. Keep in mind that my goal is 10 mill (1/100″) accuracy of reproduction.

I also did some rough pricing of PCB fabrication and found that the gold finger connector will cause a surprising cost increase over the Apple II rev 0 PCB, despite the similar board size. The cost of the Stancor transformers and caps for the power supply are also driving up cost. Despite a somewhat smaller parts count, his project is definitely starting to look more expensive than the A2 rev 0.

Once I get all the parts kitted, I plan to offer a complete parts kit to Obtronix bare PCB owners. Eventually I’ll offer bare PCB boards, and parts for Apple 1′s, similar to what I’ve offered to those interested in the Apple II rev 0 kit.

regards,
Mike Willegal

Apple 1 Replica Project Restarted #5

Sunday, November 1st, 2009

icomparision-mage-of-board
The front and back copper layers are starting to look pretty good. I can still make some improvements, but I’ll take a break from focusing on those layers and do some work on the silkscreen layer. I feel comfortable enough with progress that I’ve started ordering enough parts for about 12 boards. Attached is an image of the front copper and solder mask artwork colorized and put next to the same image of an actual original board. This kind of comparison can help with accuracy. In creating this comparison image, I found 3 to 4 things that need correcting. Can you find them? Note the hard corners of the digial traces as compared to the actual board. I intend to soften those corners, before going to production, but it will be one of the last things that I do.