Sometimes it happens that you need a wireless earphone to pass a very difficult exam, and it is expensive to buy it. In this case, you can do it yourself by following all the instructions and tasks necessary for this.
It is necessary
- - Soldering iron;
- - microcircuit;
- - coil;
- - speaker;
- - 2 batteries;
- - battery;
- - amplifier for the loop.
Instructions
Step 1
Make a loop reinforcement. To do this, use a conventional microcircuit in the case. The trigger mechanism is similar to stereo. Bring 2 and 3 legs together. The seventh and eighth legs go separately to the capacitors. Put the first end of the loop in a plus, the second in a minus. Wind a 32 ohm loop. As a battery, take any battery from a cell phone, for example, a Samsung.
Step 2
Assemble the loop amplifier using m / s TDA7052. This is the best option as the earbud will pick up the signal much better. Use a microcircuit in an SMD case inside the earphone itself. The speaker can also be taken from any cell phone.
Step 3
Wind the coil around the microcircuit and connect the coil without resistors and capacitors to the input. And to increase resistance, just wind more turns. Then add resistance as it will make the signal even louder. It must be selected precisely by volume, taking into account the number of turns. Use 2 LR41 batteries. They will fit your wireless earbud perfectly.
Step 4
Also use thinner 361A batteries if the LR41 does not fit. Their charge will last for approximately 90 minutes. The current between the ear and the batteries will be approximately 5-6 mA.
Step 5
Solder the IC, coil and speaker. It may take you about 40-50 minutes, despite the fact that there are no small details in this scheme.
Step 6
Check how your earphone works. If you have done everything correctly with the above scheme, you will be quite good at distinguishing between music and speech. The fewer turns, the worse it is audible, but there is also less noise. But, the more turns, the better you will hear and the more hiss will be. Also, with the second option, the earphone will react more strongly to all sorts of surrounding devices. If the audibility is even satisfactory, you can go to take the exam with peace of mind, knowing that your friend will prompt you through your wireless earphone.
