Transmisor Monaural Fm
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Publicado: 24 de abril de 2011
FM Band Monaural Transmitter
22 pF trimmer Use a multi-turn type for easiest frequency adjust. 0.01 uF near coil 5k 100k 1k pot Audio Input (low-Z) 33Ω 22k KV2201 1 uF + 10k 100Ω 2N4401 Manyvaractor diodes will work fine. Adjust the trimmer for good modulation. Most other FETs will work, especially RF types like the 2N4416 or switches such as the 2N4858. U310 If a 2.2 pF capacitor is used 10 pFthen use a short antenna to prevent excessive loading (under 1 foot). 33 uH
IN + + >15 VDC 10 uF LM78L12 or similar
OUT + 1 uF
5T, 1/4 inch dia. or 0.1uh molded choke.
22 pF trimmer
1pF to 2.2 pF
Delete 33 ohm for high-Z
150 Ω
The dot indicates the "hot" end of the trimmer capacitor. This end is usually the stator since the rotor will touch the trimmer tool.
A highquality monaura FM transmitter is quite useful in a variety of applications. The audio from a TV or entertainment system may be transmitted for remote or portable listening and for wireless earphonelistening. The audio from an AM receiver placed near a window can be retransmitted within a metal building where AM reception is not possible. Two transmitters will convert two portable FM receivers intocordless stereo speakers for outdoor events. A keyboard may be played through the stereo without wires simply by tuning in the transmitter. A child wil love an operational, miniature FM stationcomplete with transmit "on the air" light. Simply connect the stereo's monaural output to the transmitter and transmit CDs, tapes, microphones, and other audio sources. Connect the transmitter to thecomputer's sound card and have big speaker sound. Even silence may be transmitted. Tune the transmitter to your favorite station and when the annoying commercial starts, simply flip on the power and...silence (or the audio of your choice).
Ideas: 1) Use ground plane construction. Solder the ground connections directly to the copper circuit board material and keep the RF leads short. 2) Add a 680...
22 pF trimmer Use a multi-turn type for easiest frequency adjust. 0.01 uF near coil 5k 100k 1k pot Audio Input (low-Z) 33Ω 22k KV2201 1 uF + 10k 100Ω 2N4401 Manyvaractor diodes will work fine. Adjust the trimmer for good modulation. Most other FETs will work, especially RF types like the 2N4416 or switches such as the 2N4858. U310 If a 2.2 pF capacitor is used 10 pFthen use a short antenna to prevent excessive loading (under 1 foot). 33 uH
IN + + >15 VDC 10 uF LM78L12 or similar
OUT + 1 uF
5T, 1/4 inch dia. or 0.1uh molded choke.
22 pF trimmer
1pF to 2.2 pF
Delete 33 ohm for high-Z
150 Ω
The dot indicates the "hot" end of the trimmer capacitor. This end is usually the stator since the rotor will touch the trimmer tool.
A highquality monaura FM transmitter is quite useful in a variety of applications. The audio from a TV or entertainment system may be transmitted for remote or portable listening and for wireless earphonelistening. The audio from an AM receiver placed near a window can be retransmitted within a metal building where AM reception is not possible. Two transmitters will convert two portable FM receivers intocordless stereo speakers for outdoor events. A keyboard may be played through the stereo without wires simply by tuning in the transmitter. A child wil love an operational, miniature FM stationcomplete with transmit "on the air" light. Simply connect the stereo's monaural output to the transmitter and transmit CDs, tapes, microphones, and other audio sources. Connect the transmitter to thecomputer's sound card and have big speaker sound. Even silence may be transmitted. Tune the transmitter to your favorite station and when the annoying commercial starts, simply flip on the power and...silence (or the audio of your choice).
Ideas: 1) Use ground plane construction. Solder the ground connections directly to the copper circuit board material and keep the RF leads short. 2) Add a 680...
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