Mini Wireless FM Transmitter 88-108 Mhz.

This FM transmitter operates in the frequency band 88-108 MHz, low power electronic assembly and is easy to carry and use in our homes and with which we can start practicing some of the radio transmission.

Construction of roll:
N is the number of turns = 5 turns
D: is the radius of the coil in inches = 0.5 cm
L is the length in inches = 1 cm


Frequency Modulation (FM).
FM modulation is performed on the base-emitter of transistor Q2 and now there is a sum of the arrival rate (audio) and the frequency of the oscillator output. f 1 = Input frequency output for each input two frequencies are: f 1 = f osc osc-f-f 2 in yf = f in + f osc. in f and f 2 = f + f in osc.

Antenna:
We weld a meter length of cable at the end of a first round of the loop that is closest to the collector of transistor Q2.

Adjustment:
To function properly, we need to adjust VR1 so that we have the Q1 collector voltage between 1.5 and 1.9 volts.

Frequency adjustment:
Tune an FM radio around 95 MHz (in an area where there is no station) after a few meters from the circuit. We then apply the voltage to the transmitter and began to change the setting of C2 slowly until the background noise of silence, once achieved, we can test the performance of modulating our voice into the microphone. We also try to change the transmission frequency separately or all turns of the coil. When met to reduce the frequency and increase in separation.