Circuit of power fm transmitter transistor 2n2218 audio wireless 1KM

This small transmitter can arrive the more than 1 km in favorable conditions of emission. The modulation can be made so much with a microphone, for an electrets microphone, or other audio source. The 5 turns of enameled thread 22 AWG, with diameter of 1 cm without nucleus. Look at the capacitors that it should be ceramic. The antenna should posses
Circuit of power fm transmitter transistor 2n2218 audio wireless 1KM - schematic

s from 15 to 40 cm. Para the transmission it ties a receiver of FM (radio) in the proximities to half volume in a free frequency (that there is not any radio operating), with a wood or plastic key, rotate the screw of CV to capture the sign more fort of the transmitter, because a spurious sign can be captured. If it has difficulties of fittings, remove the coil and wind her again with more or less it turns. Look at pinage of the transistor 2n2218. Mic1 is a microphone of electrets of two terminals, THE resistor R1 makes the polarization of the microphone, perhaps it is necessary to alter the value of R1 to adapt to your microphone, values of 1k up to 10k can be tested. Preferably use plate of glass fiber, that is the appropriate for high frequency. Perhaps for better frequency stability to be necessary to place the antenna on second turn of the coil, weld the thread piece used as antenna second it turn of the coil L1.

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