นางสาวพรพรม นิสัยมั่น

1. [INC 281 MULTIDISCIPLINARY WORKSHOP WEEKLY REPORT] May 2, 2012
Name-Surname Ms. Pornprom Nisaimun
Student ID. 54261518
Group Name Instinct
Engineering Team
M, Kung, Boss, Mic, Yui, Arm, Ball, Garfield, Top, Ice
Members
Product Design P’Jub
Team Members P’Ploy
Weekly Progress
I have already tested new charger circuit. First time, I set voltage and current to charge
battery is 8 V and 375 mA (0.25C). It still affect to high temperature of LM317. So I decrease current
to 300 mA (0.2C). To limited voltage and current, I adjust RV1 and RV2 from calculation as below:
min
Ploss = (Vin – Vout) Icharge = (12 V – 8 V) x 300 mA = 4 V x 300 mA = 1.2 W
Vout =
6.75 V = (5.308 x 10-3) RV1
= 1271.665411 Ω
RV2 = = = 2Ω
PRV2 = ( ) Icharge = (0.6 V) x 300 mA = 0.18 W
After testing the circuit, I designed PCB, make PCB, put electronic device to the PCB and
test the circuit again.
Figure 1. Charger circuit Figure 2. PCB
Engineering Analysis
Strong Point
- The temperature of LM317 is cool down. - Size PCB of new circuit is same as old circuit.
- The circuit can be fined current by adjust RV2.
Week Point
- When I connect the contactor between the platform and the body, it is not strong and
sometime the contactor is disconnected.
Next Week Job
Do the English report.
Department of Control System and Instrumentation Engineering
KING MONGKUT’s UNIVERSITY OF TECHNOLOGY THONBURI

2. [INC 281 MULTIDISCIPLINARY WORKSHOP WEEKLY REPORT] May 2, 2012
Department of Control System and Instrumentation Engineering
KING MONGKUT’s UNIVERSITY OF TECHNOLOGY THONBURI