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powerful audio and video transmitter

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hm_fa_da

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ta1243 pll circuit

i need an aduio and video transmitter schematic at least 3W , i have searched for it , and found many audio transmitters , but i need both audio and viedo transmitter , video should be modulated AM , and audio should be modulated FM , receivable on TV .
 

pisoiu

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ta1243 pll schematic

Hi,
Try to mix a regular TV modulator (is available everywhere, you can find it in scraps, old videoplayers) with a PA on the same frequency as the output channel of the modulator. But be aware with radio emission...there are regulations regarding this, they depend on your area.

Best,
/pisoiu
 

egemini

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some please suggest a popular transistor for developing a PA circuit for above application. Power let it be 3W or less.

thank you
 

AL0117

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Hi,

There are single chip audio video modulators on the market like:
TA1243, TA1297 from Toshiba, TDA8722, TDA8822 from Philips, TDA6060 from Siemens. These contain a rF oscillator, PLL circuit, and their RF section is suitable for the 470-860 MHz range (some of them goes down to 38.9 MHz IF frequencies). Some of them has a PLL for the audio oscillator. The RF output level is about 70-80 dBuV (aprox -37 to -27 dBm). But please note, all of these have double sideband.
This is not suitable for transmitting in the air. Read you the regulations of country. Normally the IF (38.9 or 45.75 MHz ) signal is frequency transponed to the final channel/ frequency, of course after the necessary (Vestigial Side Band) filtering. This signal then could be amplified to the necessary power level.

You can check the application schematics of the above mentioned manufacturers.

rgds, Al
 

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