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Diode ROM PCBs
2026年02月25日 14:44:41 -05:00
diode-rom-16 Update gerber/drill files 2026年02月07日 18:35:13 -05:00
images/assembly Assembly instructions 2026年02月25日 05:51:24 -05:00
libraries/footprints/Diode_THT.pretty PCB 2026年01月20日 00:16:50 -05:00
.gitignore Initial commit 2026年01月18日 04:46:28 +01:00
LICENSE Initial commit 2026年01月18日 04:46:28 +01:00
README.md Manufacturing instructions 2026年02月25日 14:44:41 -05:00

diode-rom

Diode ROM PCBs

PCB Manufacturing

I used JLCPCB to manufacture my boards, and the design is tuned to their capabilities. It might work as-is with other manufacturers, but I haven't tested it.

  1. Go to diode-rom-16/gerber and select "Download ZIP" from the "..." menu to download the gerber and drill files.

    Manufacturing step 1

  2. Create an account on JLCPCB if you don't already have one (upload processing seems to get stuck if you don't create an account first). Then go to "Order Now". Upload the ZIP file that you downloaded in step 1.

    Manufacturing step 2

  3. Once the upload has finished, you should see a preview of the board design. For the parameters, I selected "PCB Color: Blue" and "Surface Finish: LeadFree HASL", and left the rest at their defaults. Once you're satisfied, click "Save to Cart" and go through the rest of the ordering process.

    Manufacturing step 3

Assembly

  1. Bottom and top sides of the board, with components. You'll need:

    • Up to 128 1N4148 diodes, depending on what you want your ROM to output. I'll be using mine to display hexadecimal digits on a 7-segment display. It will have active-low outputs, with 0 indicating that a segment should be on and 1 indicating that it should be off. This will require 34 diodes.

    • One 10K ohm 9-pin 8-resistor network

    • Two 74HC238 decoder ICs and two DIP-16 IC sockets

    • One 74HC245 bus transceiver IC and one DIP-20 IC socket

    • An extra IC socket to help keep the board stable when soldering the other sockets

    • A 14-pin header, either straight or right-angle

    • A 14-pin or larger female dupont connector to keep header pins aligned when soldering. Multiple smaller connectors can also work. If using straight header pins, you can use a breadboard instead of a dupont connector.

    Assembly step 1

  2. IC sockets placed on the board. The extra socket is placed in the diode grid area to help keep the board stable when soldering.

    Assembly step 2

  3. Underside of board with IC sockets

    Assembly step 3

  4. After soldering IC sockets

    Assembly step 4

  5. Right angle pin header placed on board

    Assembly step 5

  6. Female dupont connectors attached to pin header to keep pins aligned

    Assembly step 6

  7. After soldering pin header. The pins are slightly misaligned since I used two connectors instead of one larger one, but they'll still work.

    Assembly step 7

  8. Top of board after soldering pin header

    Assembly step 8

  9. Resistor network placed on board. Common pin should be towards U1.

    Assembly step 9

  10. Bend resistor network pins to hold it steady while soldering

    Assembly step 10

  11. After soldering resistor network

    Assembly step 11

  12. First row of diodes placed on board

    Assembly step 12

  13. Diode leads bent

    Assembly step 13

  14. Diode leads soldered and trimmed

    Assembly step 14

  15. Remaining diodes placed and soldered

    Assembly step 15

  16. Underside of board after soldering and trimming remaining diodes

    Assembly step 16

  17. ICs placed in sockets. 74HC238s go in U1 and U2. 74HC245 goes in U3.

    Assembly step 17

  18. All done!

    Assembly step 18