A stereo FM receiver using the TEA5711 IC

[transistor495]

You can tune any radio with varactor diodes. Any diode (or junction in a transistor) changes its capacitance a little when its reverse voltage is changed but a varactor diode is designed to change its capacitance enough to do the tuning range properly.

Sir, could Please explain me with using TEA5711 circuit diagram, how to use varactor diodes for Tunning.

You can try the basic principle as like here:



In the first image you can use the resistance as the wiper of a pot(say 10K according to input voltage and tuning range..do calculation) to change the reverse bias voltage across the varactor. Important thing is you need to isolate the bias voltage from entering the RF loop. A capacitor used here for isolation.

 

[audioguru]

could Please explain me with using TEA5711 circuit diagram, how to use varactor diodes for Tuning.

The schematic of a manually tuned AM/FM radio on the datasheet shows a 4-gang tuning capacitor. Two of the gangs are for AM and two are for FM. Simply use a suitable varactor diode for each. The varactor diodes are tuned by changing the voltage with a pot of a regulated voltage.

 

[skldj]

can you please tell me which one is better to use; tea5711 or sony cxa1538 . both are stereo ic. i have decided to build this receiver and find both ic are available in my area.

 

[mvs sarma]

@skldj,
why at all to build an FM radio when it can be bought dam cheap? your effort can better serve you, on any other gadget that could help your education and or hobby.

 

[skldj]

skldj,
why at all to build an FM radio when it can be bought dam cheap? your effort can better serve you, on any other gadget that could help your education and or hobby.

it feels good when i do it by myself..

 

[skldj]

can i use 3n200 mosfet in place of bf981. because it is hard to find..

 

[mvs sarma]

can i use 3n200 mosfet in place of bf981. because it is hard to find..

i can offer you BF998 in sot143 package
check for datasheet

they are cheaper
take 10 at rs 10 each and postage extra

 

[skldj]

wo

i can offer you BF998 in sot143 package
check for datasheet

they are cheaper
take 10 at rs 10 each and postage extra

wow! sound great to me. but where? R U SELLING IT?

 

[mvs sarma]

i had bought as a lot and used some. thus i can spare, I sent a pm to you.

 

[skldj]

yes ,i want to buy it but how? my Email skldj420@gmail.com

 

[skldj]

check your Email sir. thank you.

 

[mvs sarma]

ok, got the email too. Shall be dispatching on Monday by speed post. i would intimate you the tracking #.