Science Models
Science Fair Projects

Published on Feb 03, 2016


The objective:

Find out what an electronic adder is and how it works. I find the way computers add binary digits with an adder very interesting and I wanted to build one for myself.


First I designed my circuit using the PAD2PAD program on the Internet. Then, I printed out the circuit and ironed it on to a piece of copper. Then, I put it into a bath of ferric chloride and it ate away the copper not protected by the ink.

Next, I wiped away the extra ink with acetone leaving the copper traces. I drilled the needed holes with a high-speed drill press. Finally, I soldered the components on the PCB. Ferric chloride acid; Clothes Iron; Pencil; Double sided PCB copper; 2 74LSOO IC chips; Plastic Tupperware; Water; Stationary drill; .8mm drill bit; 2 100 ohm resistors; 2 470 ohm resistors; 2 LEDs 3mm; Laser Jet Printer; Computer; Saw; 4.5 volt battery pack; switches; toothbrush; Acetone; Powdered Bleach; Sponge; Sand Paper; Bread Board; Jumper Wires; Soldering Stand; Flash Light; Magnifying Glass; Multimeter.


In the end, the PCB that I made didnt work. When I tested the board with a multimeter I discovered the IC chip was read incorrectly. Since the PCB is a very important part of the experiment, I decided to recreate it on a breadboard.

I got the breadboard version to work by making sure the chips faced the correct way. I used the circuit to add binary digits. I had to take more time to learn about the way the IC chip worked.

I learned that electronic devices are much more complex than I previously thought. I have gotten a better understanding from this experiment about how hard it is to design a circuit and get it to work.

I learned to take more time to study the schematics and to make sure to make the circuit works on the breadboard before I solder it together. I dont think I spent enough time making sure the circuit worked.


In preparation for the County fair, I rebuilt the circuit again and this time got it to work correctly. I will be bringing all versions of my circuit at the State fair.

The main point of this project was to built a "half adder", which is the primary circuit that allows computers to do math

Science Fair Project done By Luc F. Bouchard