The earphones have found wide practical application among students during exams and tests. However, it so happens that it is expensive to purchase this device. In this case, you can assemble it yourself.
Necessary
- - soldering iron;
- - microwell diagram;
- - battery;
- - details of the circuit.
Instructions
Step 1
Purchase all the necessary parts for the earpiece. They can be found in stores or purchased online. The main thing is to remember that the smaller the elements of the device, the more invisible it will be. You will need transistors sot23 of the VS847S, KT3130B9, VS847V brands, capacitors with a nominal value of 0.1 μF, chip resistors with a nominal value of 10 kOhm, 43 kOhm, 560 kOhm. The sound source will be an electromagnetic miniature telephone, for example, TEM-1956.
Step 2
Find a micro-earphone circuit on the Internet. Study it carefully and check if you have the required items. Take a board of the required size and solder all the elements according to the general rules of SMD elements. After you finish soldering, wash the board from the flux and check with a multimeter that it is done correctly and that there is no short circuit between the elements.
Step 3
Make a receiving coil of enameled wire PEV-2 and wind about 70-100 turns on the microcircuit. Solder the ends of the wire to the board in accordance with the recommendations of the micro-earphone wiring diagram.
Step 4
Make a fasung in which the battery will be installed to power the earpiece. It can be made from any rigid metal material. For example, take a 5 kopeck coin and bend it under heat. Solder the fasung to the board and rinse off the flux. Check for a short circuit with a multimeter.
Step 5
Insert the battery into the fasung. Check for sound. To do this, touch with tweezers or a screwdriver to the bases of the transistors, if you hear a hiss, it means that the assembly of the device is done correctly. After that, assemble the earphone into a homemade case or wrap it with electrical tape. Using thick wire, make an ear holder, which is also wrapped with electrical tape or other material for ease of use.
