PCB Etching and Soldering Semi Mounted Device Component

Hi everyone,

This week will be etching process for PPG circuit. Actually this is forth etching, since the etching is not too good before. I've been learn how to etch a PCB by just watching video from youtube, you can view it here http://www.youtube.com/watch?v=RfelrrZyCYQ, it is quite easy if you just watch the video, actually it is really  trivial works. The works is as below:

1. Put on the goggles and gloves. Always remember safety first because it is deal with acid chemicals.
2. Make sure the area is well ventilated before mixing. The chemicals will produce hazardous fumes.
3. Exposed your PCB with the transparent plastic PCB layout at the UV light box for 60 minutes.
4. Mix two parts hydrogen peroxide for every one part hydrochloric acid. When mixed, they form a substance that is a severe skin irritant, and will produce toxic chlorine gas.
5. In a non-metallic basin pour enough of the solution to completely submerge the circuit board.
6. Drop in the circuit board and agitate it for about ten to fifteen minutes. Continue stirring until all copper has dissolve, and the solution has taken on a slight green tinge.
7. For cleanup, make sure you are wearing gloves. Wash the board off in cold water to remove any etching solution. Then use a paper towel or rag to dry it off completely. Set it aside. Assure that there is no solution in the workspace or containers then remove the gloves and googles.
8. Mix a one to one ratio of acetone and rubbing alcohol. Take a paper towel, dip it into the solution, and gentle rub it over the surface of the board. The permanent marker will begin to come off. Continue rubbing until all marker is gone. You should see that the circuit is now inscribed in the copper.

Below are my PCB after the etching process.

Next is the assembly process, it is include drilling and soldering as below:

1. Before drilling locate all the positions of the through hole components.
2. Drill through the board with a bit wide enough to accommodate whatever part must be placed at that location.
3. Place the components on the circuit board at their designated locations.
4. Soldering is a skill that requires practice, although it is not inherently difficult.

You can view this video http://www.youtube.com/watch?v=b9FC9fAlfQE for tutorial of soldering SMD components. Soldering SMD component is hard, that's why i need some items to make the job easier. The item is listed below:

1. Tweezers
2. Magnifier
3. Flux liquid
4. Solder wick
5. Solder wire 0.8mm
6. Solder iron with 0.5 mm tip

Below are my circuit that is still on soldering process.

Finish with the etching and soldering this week, let's go for the testing of the circuit. See you next week.

Bluetooth Research

I'm deciding to use Bluetooth as the wireless data transmitting and receiving to the Smartphone. First of all, i already decided the hardware that i should used. Below are the bluetooth hardware that used for my PPG interface with the smartphone:

1. Arduino Uno R3, which you can find here, http://www.myduino.com/index.php           route=product/product&path=37&product_id=271
2. Xbee Shield for Arduino, which you can find here as well, http://www.myduino.com/index.php?route=product/product&path=40&product_id=108
3. Bluetooth Bee, this is the link, http://www.myduino.com/index.php?route=product/product&path=50_56&product_id=105

Thanks for keep updating my blog.

     

PCB Design

Hai there,

After few weeks keep researching on how to etch a PCB, this week is my first time designing a PCB using Proteus software. Designing a PCB quite difficult, because i have to draw back all the circuit at the Proteus software then convert it to ARES. When it comes to ARES format, i have to arrange all the component and avoid wire jumper as possible. Below are my Proteus (ISIS) and ARES that already converted to the PCB layout.

Notice the circle mark, it is supposed to be LT1932, but its not available at Proteus. So, to solve this problem is, i just have to make footprint at the ARES which you can see at figure below.

Before etching the PCB, make sure all the component is fit at each soldering point or solder resist. On the left side is the upper and the right is bottom of the PCB. That's all for this week, see you guys next week.

Current Stabilier and Operational Amplifier OPA2350

Good Evening everyone,

Finally, my LT1932 current stabilizer and Op-amp OPA2350 have arrived. For your information, this is very rare components, its hard to find unless ordered or purchase online.

LT1932
In the previous post, i have post the datasheet of LT1932. At this post, i will summarize the LT1932. The function of LT1932 is used for stabilized the IR LED current to obtain the visible light output gain accuracy. LT1932 Constant Current DC/DC LED Driver in Thin SOT is used for the purposed of stabilizing the current that drives the LED and the appropriate resistor values a shown in Table below

LED Current (mA)	Resistor Value
40	562Ohm
30	750Ohm
20	1.13kOhm
15	1.5kOhm
10	2.26kOhm
5	4.53kOhm

So, the desired value that we expected is 20mA and i should used 1.13kOhm resistor at pin Rset or pin no 4 of LT1932.

The results of IR LED resistor current test is shown in table below.

I LED (mA)	R set Value
25.4	1kOhm
18.2	1.3kOhm
15.7	1.5kOhm

Figure below shows the actual component of LT1932.

OPA2350
This component also is the rare component, and i ordered it together with the LT1932. The datasheet of OPA2350 can be found here http://www.ti.com/lit/ds/symlink/opa2350.pdf. Actually, OPA2350 have 2 input and 2 output. In the circuit diagram, it is label by A and B for example OPA2350 U1:A and OPA2350 U1:B. Figure below shows the OPA2350 diagram.

It is show that for output A is using terminal 1,2,3,4 and 8. For the output B is using 4,5,6,7 and 8.

Figure below shows the actual component of OPA2350

The cost of both components is list at table below.

Component	Quantity	Price
LT1932	1	20.00
OPA2350	1	25.00
Total		45.00

The price is quite expensive because the items is seldom and hard to find. But for the successful of the project, there are no other option to make its successful, one word for it SACRIFICE. See you next week.. :)