A relay computer that adds or subtracts two 4-bit numbers made for a Capstone project
Power the computer with a 5V through the barrel jack on the top-right.
There are nine switches on the bottom left—these are the inputs. The four on the top are the A3-A0 inputs, and the four on the bottom are the B3-B0 inputs.
On the the switch on the middle-right is the additon-subtraction selector. Switch it up to add the two numbers, and down to subtract them.
Here is the BOM (bill of materials) for one of the computer, with links. Prices are included (shipping not included) but always subject to change.
| Item | Variant | Quantity | Link | Price |
|---|---|---|---|---|
| Relays (100x) | SRD-05VDC-SLC | 20 | AliExpress | $19.27 |
| Diodes (100x) | 1N4007 | 28 | Amazon | $5.99 |
| LEDs | red, 5mm | 33 | ||
| Switches (10x) | MTS-102 | 9 | Amazon | $7.99 |
| Barrel Jack | 5.5mm OD | 1 | ||
| Resistors | 220Ω | 33 | ||
| PCB (5x) | 1 | see how to order | $15.80 | |
| Total | 125 | $49.05 |
Head to JLCPCB and upload the gerber file at production.zip.
Use the default options for customizing your order. Use this table for reference:
| Option | Selection |
|---|---|
| Base Material | FR-4 |
| Layers | 2 |
| Dimensions | 210 * 140 mm |
| PCB Qty | you choose |
| Product Type | Industrial/Consumer electronics |
| PCB Thickness | 1.6mm |
| PCB Color | you choose |
Select a build time and add the PCB to your cart.
For my order, the 5 PCBs costed $15.80 and the shipping costed ≈$30, plus tarrifs. I ended up paying ≈$50. These prices are subject to change.
For any questions about this project, feel free to create a new issue on this repository.