The inspiration for this project came from a YouTube video by Veritasium showing the conception of computers, and how they were first built and evolved. Within that video, Veritasium shows an 8-bit adder.

I set out to make a smaller 4-bit version of the adder and started researching how relays were used to make logic gates and full adders. I found two helpful websites one with diagrams and a walk-through of the 4-bit relay adder that they made, and the other was a great resource showing how to make logic gates, flip flops and full adders. Both of the websites had useful graphics and diagrams that showed the relay configuration/wiring to assemble a full adder with relays. I discovered that using relays to build a 4-bit adder can be quite challenging due to the complexity involved in wiring and configuring the relays. However, this is a challenge that I was ready to tackle to provide me with a deeper understanding of the complexities of modern computers.

To further enhance my understanding before starting on the relay version, I built a test 4-bit adder using XOR and AND gates inside ICs that I already owned. This allowed me to gain practical experience in implementing multiple full adders together.

Blue and green LEDs represented the binary values of the inputs, while the result of the addition was displayed in the red LEDs.

The Breadboard with the ICs, LEDs and power regulator on it (before anything was connected)

0001+0001=00010

1010+1001=10011

I successfully tested the adder with different binary inputs, such as 0001+0001=00010 and 1010+1001=10011, and obtained the expected outputs. This experiment not only reinforced my knowledge of digital logic but also provided me with a visual representation of how binary addition works.

After completing the 4-bit adder, I decided to take my understanding further by creating some test gates using the relay that I currently have. This allowed me to explore the practical aspects of relay-based logic circuits and deepen my understanding of their operation.

Unfortunately, this project is not finished yet, I will update this page with more details as more progress is made.