1. Automatic heat source finding laptop cooling pad By Team 26
ECE 445
Automatic heat source finding laptop cooling pad
By Team 26

2. Introduction Objectives Design review Block diagrams and schematics
Success and challenges
Future improvements

3. Objectives Features: Automatic heat finding system
Fan speed changes according to the temperature
LCD display panel

4. Basic Design A skeleton case (including tracks) 4 IR sensors
Circuit board
Bumper system

5. OUR DESIGN

6. Block diagram

7. Grove IR sensor
This sensor outputs an analog voltage (0 ~ 1.1V) according to target’s temperature
Measure accuracy:  ±2℃
Temperature measure range:  -10~100 ℃
Nominal measure distance: 9cm
Cut on wavelength: Min 4.7 um, Max 5.3 um

8. Sensors in our design

9. Feature of the IR sensors
This sensor outputs an analog voltage (0 ~ 1.1V) according to target’s temperature
Measure accuracy:  ±2℃
Temperature measure range:  -10~100 ℃
Nominal measure distance: 9cm
Cut on wavelength: Min 4.7 um, Max 5.3 um

10. Circuits

11. H-Bridge SN754410
There are basically three states for the H-bridge we use
Function table:

12. H-bridge (continue) What we have for H-bridge
Output current range <1A
Supply voltage range 4.5V to 36V
What we need
0.6A current for fan
12V voltage for both fan and motor

13. Voltage regulator
Formula: ( 𝑅 𝑓 𝑅 𝑔 )=( 𝑉 𝑜𝑢𝑡 𝑉 𝑖𝑛 −1)

14. Micro-controller Atmega328 PU Max Op Frequency : 20 MHz
Flash (Kbytes) : 32 Kbytes
14 digital pins
6 analog pins
Output maximum voltage: 5V
Output maximum current : 40mA

15. PID control and the fan
Both P and D value are set high for quick reaction to rising or falling temperature
(Kp=15 Ki=0.01 Kd=2)
We programmed the fan to have it follow the hottest spot on your laptop

16. Reset button Four reset buttons attached on each side
When the fan hit the wall it would stop moving toward it’s previous direction

17. Several changes we made
Switch from TMP006 to Grove IR sensors
Use a H bridge to drive the motors instead of a voltage amplifier
Change from PCB board to vector board

18. Tmp006

19. The temp006 circuit we built
The temperature we measured using this circuit is unstable (from 10°C to 40°C)
It took a whole afternoon to solder this and we need 4

20. PCB

21. Problem with this PCB
We did not left enough Vcc and ground pins when we design this PCB
We did not left pins for the input from our bumper
The output for the motors changed as we insert our h bridge into the board (we still cannot figure out why)
As a result we changed to a vector board

22. Accomplishments Fan spins according to the temperature
Correct tracing of the hotspot
LCD works perfectly
Programs runs flawlessly
Reset bumper detects boundary conditions

23. Difficulties Spend way too much time on soldering
Program at start was way too buggy
Spend a lot time on finding the correct IR sensor
Burned at least 3 chips and a LCD
Gluing everything together

24. Future improvements Cut down the cost for IR sensor
Make the cooling pad more mobile
Have everything powered by the USB
Have the desired temperature set by user
Make the fan more quite
Make the motor more quite

25. Thank you!
Questions?
Comments?
Flowers?