Purchasing Item

Welcome Back!

Everything is on schedule, i already purchasing component for my PPG circuit. Figure below shows the component that i had bought.

As can be seen in the Figure, the Surface Mounted Device (SMD) components is small. It is not more than 5mm width and 3mm length, and it is totally different with through hole components. This method for producing electronic circuits in which the components are mounted or placed directly onto the surface of Printed Circuit Boards (PCBs). There are no leads or either smaller leads and it may have short pins or leads of various style.

Why is choose SMD as component for the PPG circuit is

• Smaller components.
• Lower initial cost and time of setting up for production.
• Fewer holes need to be drilled.
• Small errors in component placement are corrected automatically as the surface tension of molter solder pulls components into alignment with solder pads.
• Lower resistance and inductance at the connection; consequently, fewer unwanted RF signal effects and better and more predictable high-frequency performance.
• Better EMC compatibility (lower radiated emissions) due to the smaller radiation loop area and the smaller lead induction

The cost of all the item purchased is shown on table below:

The cost of all the item purchased is shown on table below,. 

Components	Value	Quantities	Price (RM)
Capacitors (tantalum or ceramic, voltage rating?) below 50V	4.7uF 1uF  12pF 10uF	10 2 1 1	8.00 3.00 1.50 2.30
Inductor	6.8uH	1	2.80
Resistors	1kohm 1.3kohm 22kohm 1Mohm	10 10 10 10	1.00 1.00 1.00 1.00
Diode Schottky (20V 1 A)	1 A,40V	2	8.00
Diode Zener	5.1V	2 pieces	4.80
LED	5V	10	2.00
Total			36.40

The total for the components is not much and it is affordable. But, the LT1932 and OPA2350 i have to order because it is seldom used and the stock is not in the electronic shop. The ordered have been made, and i have to wait for 3 working days for the components to arrive. Below are the list of the electronic shop where is purchasing the item:

1. Online Component Sdn. Bhd. (www.online-components.com.my)
2. MSC Supply and Service 

Any rare components can be found at MSC Supply and Service, credit to this company because almost half day searching for the LT1932 and OPA2350 and it only be found and can be easily ordered at that electronic shop. That's all for now. Thank You.. See u Next Week..

Circuit Simulatioin

When its come to simulation, there's many things that i think how i should simulate the circuit. So, after keep asking Mr. Google, finally, its come to solution. The solution is i have to test the circuit 1 by 1. From the First circuit, the IR LED Current Stabilizer, Second circuit is Trans Impedance circuit and the last circuit is sallen key filter circuit. The result should be almost the same as theory result that i found in the article. Figure below shows the circuit and its result. I skipped the IR LED current stabilizer simulation, because i can't found LT1932 component, and plus, my supervisor assure the circuit will have no problem if the connection is right, because the circuit is original from the datasheet of the LT1932 which you guys can view here http://cds.linear.com/docs/en/datasheet/1932f.pdf.

Transimpedance Circuit 
Started with the trans impedance circuit simulation, you can see figure below:

Figure above shows the simulation circuit for trans impedance circuit. It is using Proteus for the simulation software. As can be seen it is 1.5V supply to the circuit and resulting 24.01mV. A transimpdance amplifier is an amplifier that converts current to voltage. Its input ideally has zero impedance, and the input signal is a current. Its output may have low impedance or in high-frequency applications, may be matched to a driven transmission line, the output signal is measured as a voltage. I assuming that the input voltage is 1.5V from the IR LED Current stabilizer and it is supposedly current. The noise gain for example the noninverting closed loop gain of this configuration determines the stability of the circuit. The reason for this is that any noise signal, no matter how small, can trigger an unstable circuit into oscillation. The DC gain is set solely by the resistors. The pole frequency is set by the feedback network, just as in the impedance function. Table below shows the current input and output for the transimpedance circuit.

Current Input (mA)	Voltage Output (V)
0.010	0.01
0.022	0.02
0.031	0.03
0.04	0.04
0.052	0.05
0.061	0.06
0.072	0.07

Sallen Key Low Pass FIlter
The second circuit is sallen key low pass filter. See figure below:

The circuit above is simulated using Multisim software. It is hard to simulate using Proteus, so i come with the solution by using Multisim. As can be seen, i'm not using OPA 2350 for the operational amplifier. Supposedly it is OPA 2350, but, i can't found it inside Multisim. As my supervisor advised, it is almost the same amplifier, as long as the result is there. So the function generator is set to 5V amplitude and the Frequency is set to 5Hz.
The sallen-key filter is a simple active filter based on utilizing op-amp stages, which is ideal for filtering analog frequencies. It is one of the most widely used filter topologies. One reason for its popularity is that this configuration shows the least dependence of filter performance of the performance on the performance of the op-amp. Another advantage of the configuration is that the ratio of the largest resistor value to the smallest resistor value and the ratio of largest capacitor value to the smallest capacitor value are low, which is good for manufacturability. A serious drawback is that the filter is not easily tuned. A low pass filter is a filter that passes low frequency signals but attenuates signal with frequencies higher that the cutoff frequency. Desire cut off frequency is 10 Hz which can be seen on the simulation, i get the 10 Hz cut off frequency.


As a summary, the both amplifier play important role to in very low frequency applications and it is commonly used in receivers for optical communications.

That's all by now.. Thank you.. Keep in touch..

Hai Everyone, How are you? This is First week for my final year

Continue from Week 14,

Hai everyone, i'm getting ready to start new semester, and this is my final year here at UniKL BMI. Once again, this is Final Year Project and this semester will start to busy to purchasing component, constructing, testing, troubleshooting and presentation for the project. Usually for the first week of the semester, still relax and introduction of the chapter. In this week, i'm gonna meet my Supervisor Sir Saiful Yusri to get refresh about the project. What i should this final semester for my Final Year Project 2 is:

1. 9 - 13 September 2013, First Week - Meet Supervisor
2. 16 - 20 September 2013, Second Week - Test the circuit using simulation
3. 23 - 27 September 2013, Third Week - Purchasing component
4. 30 September - 4 October 2013, Forth Week - Ordering component LT1932 and OPA 2350
5. 7 - 11 October 2013, Fifth Week - Design PCB
6. 14 - 18 October 2013, Sixth Week - Bluetooth Research
7. 21 October - 25 October 2013, Seventh Week - PCB Hatching and Soldering SMD Component
8. 28 October - 1 November, 8th Week - Bluetooth Purchasing
9. 4 - 8 November 2013, 9th Week - Android Programming and testing
10. 11 - 15 November 2013, 10th Week - Bluetooth Programming and testing
11. 18 - 22 November 2013, 11th Week - Testing and troubleshooting the wireless Bluetooth PPG
12. 25 - 29 November 2013, 12th Week - Ready for Final Year Project Report
13. 2 - 6 December 2013, 13th Week - Ready for Final Year Project Presentation

Hope all is running on track. Wish me the best in this semester!! See you next week.

Received PPG from My Supervisor

Dear All,

Actually today i'm not feeling well, it have been 2 days of dizziness and i don't have mood to have my lunch and dinner. Well, that's life. I met my supervisor this afternoon at 2.30 pm because he asked me to take the PPG devices. Before handover to me the PPG, we discuss a bit about the PPG and circuit need to be constructed.

Inside the PPG there are LED DC Current Source and Photodetector, while the end of its is 9 pin "D" connector of male. The brand of the PPG is NELCO oximeter finger probe. Sir Saiful Yusri which is my supervisor explained to me about the functions of the connecter pin which is as table below:-

Connector End Pin	Pin Name	Description
9	Phototransistor cathode	Green wire
5	Phototransistor anode	White wire, phototransistor detects level of IR and/or red light transmitter through the finger
2	LED1	Red wire, anode of the IR LED, cathode of the red LED
3	LED2	Black wire, cathode of the IR Led, anode of the red LED

Those are important configuration pins because all of its link to the filter circuit, amplifier and interface with microcontroller.

To make this works, we need IR LED current stabilizer LED current is between 5mA and 40mA. We will used LT1932 circuit for it. Therefore, for the transimpedance, we choose this because photodiode will produces a strong tendency for the amplifier to go into oscillation at some high frequency above the gain bandwidth cutoff. This problem can be eliminated by adding a small capacitor in the feedback loop, which lowers the gain at very high frequencies. For the filter circuit we'll we use the Sallen-Key Low Pass Filter which are buffer circuit. And the output of it will interface with the microcontroller which will send the signal to the Smartphone using GSM.

That's all for now......See you again...Will come back in next week probably..

Project Proposal Preparation

Week 13,

Day pass by really pass, now is week 13, and we have to prepare for project proposal which need to be submit by next week. Actually, the my proposal have been prepared for the last 3 weeks before, and at this week i just need to check it all and see which part i should add more. Below are my contents of the proposal.

Contents

1.0 introduction.. 2

1.1 About Heart Rate. 2

1.2 What is Photoplethysmography?. 2

1.3 Background of the Project. 3

2.0 problem statement.. 4

2.1 Design that Inhibits the Ability. 4

2.2 Expensive. 4

2.3 Limit Range. 4

3.0 aim and objectives. 5

4.0 project scope and limitation.. 6

4.1 Project Scope. 6

4.2 Limitation.. 6

5.0 expected outcome. 7

6.0 literature review... 8

6.1 References from Article. 8

6.1.1 Title: Portable Heart Rate Detector Based on PPG with Android Programmable Devices for Ubiquitous Health Monitoring System... 8

6.1.2    Title: Wearable Wireless Photoplethysmography Sensors. 8

6.1.3     Title: A Wireless Cardiovascular Monitoring Device and Its Clinical Tests. 9

6.1.4  A Real-Time Cardiac Arrhythmia Classification System with Wearable   Sensor Networks  9

7.0 methodology.. 10

7.1 Android Application.. 10

7.2 Wearable Sensor. 11

Android Digital Processing of the Heart Rate

I'm wondering how is it the algorithm to process the signal of the output from the PPG. This is kind of new things for me because, i'm not to sure how the data will be processed. So then, i'm thinking about to make a flow chart as below:-

The most important is the peak detection as the result that will be used as heart beat rate per minute.

Receiving Few Articles from My Supervisor

Thanks to my supervisor, he had giving me few article regarding the information about the PPG, wireless communications technology and a bit about the Android Programmable Devices information.

The first article is "Portable Heart Rate Detector Based in Photoplethysmography with Android Programmable Devices for Ubiquitous Health Monitoring System. This article  explain about miniature portable heart rate detector system is implemented by modern hardware IC's and simple sensor circuit with software executable on bot PC and Android platform. The biosignal is first extracted via PPG principle into electric signal. Then a microprocessor is used to convert biosignal from analog to digital format, suitably for feeding into an RF module. On the receiver end, the computer or smart phone can analyze data using robust algorithm that can detect peaks of the PPG waveform, hence to calculate the heart rate. Some application software running in windows and android phone have been developed to display heart rate information and time domain waveform to users for health care monitoring. This article also state that the data can be sent to compute console using existing networks (3G,2G,4G,WiFi,etc) for health databese logging purpose.

From this article, it is explained more about the project.. Thanks for keep updating at my blog.....