2 layers212.5 × 99.5 mm
2 layers78.7 × 47 mm
Coco3AppleRGB
mrojas36/Coco3AppleRGB1Tandy Color Computer 3 RGB Port to AppleColor RGB Monitor (IIgs version)
- Size
- 78.7 × 47 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 10
- Nets
- 28
- Pads
- 55
- Tracks, vias
- 92, 15
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 5 Sep 2021
- Updated
- 10 Sep 2021
Overview
Coco3AppleRGB is an open-source printed circuit board by mrojas36, from the mrojas36/Coco3AppleRGB repository on GitHub, published under the CC0-1.0 licence. It is a 2-layer board of 78.7 × 47 mm with 10 parts on 28 nets, routed with 92 tracks and 15 vias.
It is built around the 74HC86D and PJ-037A. Its parts include 3 capacitors, 3 resistors, 3 connectors and 1 IC. It belongs with the lEDs and displays boards of this library.
Main components
2README
README.mdCoco3AppleRGB
This card will interface the Color Computer 3 RGB port to an AppleColor RGB Monitor (model A2M6014). It was created and shared with the CoCo community. The design is provided here for whatever purpose you would like: make for yourself, build, sell, or modify.
Overview
The card was designed from an schematic from 1996 by Tomi Engdahl. The circuit was modified to work with the AppleColor RGB Monitor. Here is the original schematic:
I bread boarded this circuit and made modifications (shown in pencil) to get it to work with the Apple Monitor.
With a bit of fiddling, I was able to achieve a display:
The key to getting this to work was recognizing that the Apple Monitor needs a composite sync (CSYNC) in order to display. The CoCo3 has separate horizontal and vertical sync signals. This circuit will take those signals, flip them, and then interface them into a composite signal (show on the oscilloscope). Here is the resulting schematic:
Design
The project was built in Kicad and has all the project files included. You can get a copy of Kicad from https://www.kicad.org.
Kicad was also used to layout of the PCB, show here:
The bill of material is straightforward and only contains easy to find parts. At the time of writing the total board cost is under $7 USD.
The finished board:
Case
This project also contains a 3D printable case design. The case is in two parts: Top and Bottom. No screws are needed as the bottom slides into the top part for a snug fit.
The case was designed using DesignSpark Mechanical. This is a free design tool. You can download the tool from https://www.rs-online.com/designspark/mechanical-software. The design files are included in the Case folder.
Here are some photos of the finished case:
Additional Parts
The adapter works very well and 80 column text is very legible. To complete the set you will need a 5VDC Power Adaptor with a 5.5mm x 2.5mm plug, center positive. You will also need a 10 pin ribbon cable to connect to the underside of the CoCo3.
Complete - Enjoy!
Parts
10| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | 2.2K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1, R2, R3 |
| 2 | 22uF | Capacitor_SMD:C_1210_3225Metric_Pad1.33x2.70mm_HandSolder | C1, C2 |
| 1 | 100nF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C3 |
| 1 | 74HC86 | Package_SO:TSSOP-14_4.4x5mm_P0.65mm | U1 |
| 1 | COCO3_RGB | Connector_IDC:IDC-Header_2x05_P2.54mm_Vertical | J1 |
| 1 | DB15_Female_MountingHoles | Connector_Dsub:DSUB-15_Female_Horizontal_P2.77x2.84mm_EdgePinOffset9.90mm_Housed_MountingHolesOffset11.32mm | J3 |
| 1 | PJ-037A | Footprints:CUI_PJ-037A | J2 |
Similar boards
- 4 layers146.1 × 55 mm
StarGate MainBoard
plhsystems/stargate-mainboard-esp32
Mainboard for Kristian's stargate projects, based on ESP32-S3
171 parts4 - 2 layers90.2 × 66.5 mm
PyControl DSeries
Karpova-Lab/pyControl-D-Series-Breakout
A breakout board for use with pyControl behavior control framework
17 parts2 - 2 layers100 × 81.3 mm
- 2 layers198.1 × 139.7 mm
- 2 layers72.9 × 60.9 mm
- 2 layers48.6 × 17.2 mm
- 4 layers108 × 79.7 mm
Questions
How big is the Coco3AppleRGB PCB?
It measures 78.7 × 47 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Coco3AppleRGB use?
10 parts, built around the 74HC86D and PJ-037A. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Coco3AppleRGB KiCad files?
From the mrojas36/Coco3AppleRGB repository on GitHub, at the commit this page was made from: the board is Coco3AppleRGB.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Coco3AppleRGB design in my own project?
Its repository publishes it under the CC0-1.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).