Record mobile phone conversations.

Let's make a mobile phone record lead yourself to save money.

Phùng Mai

Tôi thường xuyên phỏng vấn và thâu thanh các cuộc điện đàm với các tù nhân lương tâm hoặc gia đình họ,  (www.tnlt.net) trước tiên để ủng hộ tinh thần vì lòng dũng cảm và việc họ đã làm khiến họ phải chịu tù tội, gia đình họ bị phân biệt đối xử. Trước đây tôi dùng điện thoại để bàn và thẻ điện thoại để tiết kiệm tiền gọi về Việt Nam, nhưng gần đây có công ty Lycamobile, họ cung cấp dịch vụ viễn liên về VN qua điện thoại di động với giả rẻ hơn các dịch vụ thẻ điện thoại, vì thế tôi nghĩ đến dùng điện thoại lưu động để phỏng vấn tù nhân lương tâm và gia đình họ. Đã phỏng vấn thì phải ghi âm, nhưng điện thoại lưu động không có đường dây để mình nối vào máy ghi âm hay computer. Tuy có nhiều cách khác nhau để ghi âm điện thoại di động nhưng đều rất đắt tiền, tôi đã sáng chế mạch điện này với giá dưới 10$ để interface giữa máy điện thoại lưu động của tôi và computer cho mục đích thâu thanh của tôi với tù nhân lương tâm Việt Nam.

There are many ways to record your telephone conversations. Traditional methods were done at the users end by using a small device contains a decoupling transformer to attach to the phone lines (to interface between phone lines and a recorder or computer). It has become challenging with mobile telephones as they do not have lines for you to connect a device to. However you may be able to purchase a mobile phone which has an inbuilt recording function. This type of phone can be expensive and may limit your recording times, or you have to register with a company to record your conversation in the networks level which would then need to be downloaded to your PC. You will have to purchase a software and open an account with them. Normally you must pay monthly fee to maintain this account and there may be hidden fee such as services and software upgrade charges.

I prefer the traditional methods to have a device that I own. I don’t have to pay monthly fee or service charges. I can record my conversation as long as I want, as many time as I need to, no any extra fee I have to worry about. More importantly is. It costs me less than $10 to make it. I made this device myself and I called it a “mobile phone record lead”.

1) You may not like this step, it is not some thing you are normally do to any headset. Your mobile headset has two earpieces, from now on you only listen to one earpiece, another earpiece will be cut off. You must cut one of the earpiece off as shown in the picture above. (Keep the off cut earpiece for later use) Inside the cable there will be two fine (copper) conductor cores, you need to separate and protect them with a small cable insulator. 

2) Carefully open the off cut earpiece. Inside is a tiny speaker, carefully remove this speaker and replace it by a tiny microphone (Insert or PCB mount microphone) 

3) One end of a 10K Ohm resistor is soldered connected to one conductor cores, another end of resistor is soldered to one pin of a Microphone. Note that this microphone is polarized, so this end of resistor must solder to the pin of microphone that is NOT connected to the body of the microphone.

4) One end of resistor connected to microphone above is also soldered to the center pin of the 3.5mm jack.

5) Solder another copper core to another pin of Microphone, and also solder connected to the outside pin (ground) of the 3.5mm jack

6) Use cable ties to secure all solder connections above, make sure the solder joints are not moving when  you are using this lead, if you don't secure the solder joints, they will break easily.

I experienced that,the smaller soder joits the better sound quality. The local radio station will affect your audio recording quality if the soder joints too big. All components joints should be soldered directly and close to each other also the solder joints as small as possible.

This headset is supplied together with a phone when you buy it, you must cut one of the earpiece off to connect to transformer. Mic2 is original Microphone for mobile network. Mic1 is used to record your own voice. On the photo, Mic1 is the earpiece holder, part of  the headset cut off, the speaker inside was removed and replaced with a Microphone. I reused the earpiece holder to make Mic1 look nice. 

You don't have to have a computer or laptop, you can connect this lead to any type of recorder. This lead is a device interface between your mobile phone to a recorder.

Listen to my first recording test with my friend on mobile phone. 

Remember you must let other person know you are recording the conversation. It's a law!

Using Laptop to record Samsung Mobile (C5220) which have USB connector for headset 
Dùng computer thâu thanh điện thoại Samsung loại USB headset

Use Surface RT Tablet To Record your iPhone Conversation 
Dùng Surface RT Tablet thâu thanh cuộc điện đàm qua iPhone. 

Using laptop to record your iPhone conversation
Dùng computer thâu thanh cuộc điện đàm qua iPhone

Simple way to record iPhone conversation
Cách đơn giản để thâu thanh cuộc điện đàm bằng iPhone