TDA 7000 FM Radio - Help Please

Thread Starter

Shaira Rose

Joined May 9, 2016
10
I would say you have blown the chip up putting it in the wrong way, i would make the circuit using the varicap diode, instead of the coil, use veroboard instead.
Sir, does the circuit with adjustable coil works? I want to confirm it before I will make it on PCB thanks in advance guys! Sorry if I have to post here. This is the closest forum thread so far that relates on my problem.
 

Thread Starter

Shaira Rose

Joined May 9, 2016
10
Hello,

As the FM receiver has to work at about 100 Mhz, a breadboard will not work.
In the datasheet there is a drawing of the PCB given.
I also have attached a couple of application nots on the TDA7000.

Bertus
Thanks for the fast response Sir Bertus! It helps a bit but can you confirm if this circuit will work as an fm receiver?
 

Attachments

Thread Starter

Shaira Rose

Joined May 9, 2016
10
Hello,

L1 and C1 will make the oscillator tuning circuit (VCO in the schematic).
Changing the value of either will change the frequency.
Normaly a variable capacitor is used, but a variable inductor will also work.

View attachment 105766

Bertus
Thanks again for the lightspeed response Bertus! But I'm curious about the values of Cs, Cv and Cp?
 

RichardO

Joined May 4, 2013
2,271
Maybe, maybe not. You need to look at the manufacturers data sheets to see how they expect their devices to be used.

Keep in mind that an FM radio operates at over 100 MHz. At this high frequency the physical construction of the circuit is tricky. Look at the data sheet for the TDA7000 for an example of a recommended PCB layout.
 

absf

Joined Dec 29, 2010
1,942
Here are more information on the TDA7000 FM radio here. There are PCB layout but not made. And I saw this a few years back so no idea if the kits is still available....

Allen
 

vol_

Joined Dec 2, 2015
93
From my experience with LM386 i wouldn't use it as an audio amplifier. The distortion is hand to hand with the IC.. At about 0.25W of output power it already gives its full distortion. More for this in its datasheet.
 

Thread Starter

Shaira Rose

Joined May 9, 2016
10
Update: Ive made the circuit. But it has alot of noise. Maybe from the lm386 amplifier circuit. Or somewhere else in the circuitry. Any ideas guys?
 

vol_

Joined Dec 2, 2015
93
Update: Ive made the circuit. But it has alot of noise. Maybe from the lm386 amplifier circuit. Or somewhere else in the circuitry. Any ideas guys?
Are you running the circuit with 9V supply? LM386 will have noise for sure if you are. Try to omit the 4.7uF cap at pins 1 and 8. If there is no noise, LM386 gets the fault. If, then, gain is not enough for you, you can try two things or both (with the 4.7uF cap connected):

6V supply and
connecting LM386 in bass boost configuration.

This is done connecting a 0.047uF or a 0.033uF capacitor in series with 10K resistor from pin 5 to pin 1.

More about this in the end of LM386 Audio Amplifier Analysis.

About TDA7000 i don't have a clue.

Also try to describe the noise. Maybe someone with more experience will have a thought about the situation.

Good to see a girl here. I don't like only men places.

Cheers
 

Attachments

Thread Starter

Shaira Rose

Joined May 9, 2016
10
Are you running the circuit with 9V supply? LM386 will have noise for sure if you are. Try to omit the 4.7uF cap at pins 1 and 8. If there is no noise, LM386 gets the fault. If, then, gain is not enough for you, you can try two things or both (with the 4.7uF cap connected):

6V supply and
connecting LM386 in bass boost configuration.

This is done connecting a 0.047uF or a 0.033uF capacitor in series with 10K resistor from pin 5 to pin 1.

More about this in the end of LM386 Audio Amplifier Analysis.

About TDA7000 i don't have a clue.

Also try to describe the noise. Maybe someone with more experience will have a thought about the situation.

Good to see a girl here. I don't like only men places.

Cheers
Thanks Im observig the noise through the oscilloscope to get some idea hoe to lessen it. This site is amazing for like a student me.
 
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