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Return to BlogMiniature FM Transmitter with High Sensitivity
Posted Jan 25, 2012 at 2:23 pm
Figure 1
The project produces a sensitive FM transmitter that can transmit the signal up to 45 yards and can pick up the signal up to 100 yards from its sensitivity.
The coil is being used to select the desired frequency during the operation and it does not require special parts. The diameter of the coil is one centimeter which has a specification of 24 AWG sire. It has 5 loops which can be easily created with the use of a pencil. Adjusting the frequency is the last step that has to be done. The coil can be made wider by using a toothpick until the frequency is measured to be between 89 MHz to 104 MHz. Once the device has been tuned, the coil should be fixed using hot glue so that the frequency will not change.
The circuit can be constructed in a breadboard so that testing can be done to ensure that there will be no problem before soldering the parts. The whole FM transmitter device can be placed in the PCB after the testing and the verification. The microphone should not be close to water to avoid change in frequency.
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2 years ago: I got curious on the caution of not getting the microphone close to the water. How will the water change the frequency? Can someone explain?
1 year ago: The water can change the frequency by altering the self-capacitance of the device. Just like when you touch an antenna and a signal gets better or worse, the capacitance of the device, relative to ground, changes in proximity to water.