From Conception to Completion

Testing

After the last component had been soldered in place, the circuit was tested. On the veroboard, a small section of connection in between the pins of IC was cut to avoid short circuit. A 5V power supply was connected to the circuit. A truth table containing 16 combinations of possible 4-bit binary and its constituent Gray code was prepared. The power supply was on and all combinations were tested using the circuit. All components are working fine, the outputs are perfectly correct and match with the truth table. From the initial design of the circuit, to the completion of the circuit, took us only 1 week, and it succeed in the first attempt. 1 week of hard work and dedication has paid off, thanks to the cooperation of group members. All of us are so overjoyed.

Modification

This modification is not an error correction. It is to improve the portability of the design and to improve the physical appearance. A lab assistant of the EE Lab had observed our circuit and suggested that we replace our LEDs wires with a longer, flexible wire so that it can be bent and packed together nicely, rather than using the initial wires that are shorter and inflexible. All wires connecting the LEDs and the switches to the veroboard have to be removed and replaced with the new wires. He also insisted that we replace our LEDs(very dim and cheap) with a brighter one. The new LEDs have 2 colours: green & red(old one shows green only). It is brighter and looks nicer. We set the green LEDs as input indicators, red as output. The modification was all done by me at home, helped by group members at the lab. After 2 hours of modification at home, the circuit is now physically appealing. I had also added the power supply circuit containing capacitors, transistor and battery on the veroboard. Now, the design is completely portable and does not need to rely on fixed power suppply unit.


Top: circuit design before modification
Bottom: circuit design after modification

2nd Testing

The board is tested again to make sure that no error occurs after modification. The circuit work successfully. It is fully portable and is ready for packaging. The specification of the circuit is shown below:
4-bit binary to Gray code converter.
Powered by 74LS86 IC
5V power supply
Support up to 5-bit conversion(upgradable)