Electronics Convergence and Communications Technology ? Blog …

The integrated chip of FM radio is numerous, now take radio that TDA7088 and TDA2822 form as examples to introduce FM radio integrated circuit briefly.

TDA7088 and TDA2822 are integrated chips of radio that Dutch PHILIPS Co. produces, among them TDA7088 the electricity tunes FM up and receives the integrated circuit, TDA2822 is that the integrated circuit is put in one pair of sound channels work of little power. This radio is used earphone as the aerial, have small peripheral the intersection of component and little, the intersection of sensitivity and high, the intersection of performance and stable, little separating degree to be high making and debugging characteristicking such as being simple noise. This radio has two frequency modulation wave bands: A wave band 76- 88MHz With B wave band ? 88- 108MHz ,Among them A wave band is specialized receiving the program that the school transmitter launched, a lot of universities broadcast English program such as now, and English Test Band 4 and 6 hearing has an examination etc. and suitable for receiving with this kind of radio. B wave band can receive the normal frequency modulation program. TDA7088T has adopted advanced low intermediate frequency technology, has cancelled intermediate frequency voltage transformer, ceramic wave filter, aerial and is defeated by people the frequency modulation return circuit, save the variable electric capacity originally shaken grade, the function that and inside has set up and searched the platform and quiet and made an uproar automatically, so the peripheral component has reduced a lot compared with other radios.

Tune the circuit diagram of the radio up for FM electricity. Now sketch operation principle and signal procedure of the circuit of this radio.

Tune the circuit diagram of the radio up in Fig. 1 double -band FM electricity

Energize, sense the intersection of FM and signal from earphone, signal fail from 11 foot of TDA7088T people reach integrate yuan, through show, mix, in there show is putting, ancient bronze mirror after,compound stereoly by signal, switch export from 2 foot, via R2, R3, C15, compensation that C20 make up behind the network, fetch after the a partial pressure by the intersection of potentiometer and RP and then through being quiet to make an uproar, make a gift of 7 feet of TDA2822M, after TDA2822M power amplification, export from a foot, is coupled the audio frequency signal to the earphone by C23, drive the earphone to sound.

While searching the platform, press and search for the key S1, S end of RS trigger within TDA7088T is located ? 1 ? ,The ones that are controlled by the trigger flow permanently the source charges the electric capacity C7, the voltage of C7 both ends is rising constantly. Voltage this by R1, add to shake to become, hold diode at the BB910 return circuit originally, enable originally shaking the frequency to change and go on and tune up. When receiving the radio signal, the signal will export the high level while measuring the circuit, R end of putting RS trigger is ? 1 ? ,The trigger is turned, the ones that are controlled by the trigger flow permanently the source stops C7 correctly, charge, meanwhile, the ones that are outputted by the audio frequency and controlled flow permanently the source begins to charge C7, control the automatic frequency, lock the program listened to in residence. When pressing and resetting the key S2, tuning the voltage up and is put, originally shake the frequency and get back to the lowest frequency of C7 both ends.

This entry was posted on Sunday, July 17th, 2011 at 9:51 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

Source: http://hujk.org/fm-radio-integrated-circuit/

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