# Questions regarding TDA7000

#### darker_polar

Joined Dec 13, 2012
1
I just finished my course in electronic circuits, and I must admit I'm still unfamiliar with the field. Now, I'm trying to create a simple FM receiver radio, and I found out that there is an IC called TDA7000 that miraculously contain all the circuits needed for creating a radio, thus creating a cheap and efficient solution. Here is the data sheet:

http://www.pira.cz/pdf/TDA7000.pdf

However, I do want more than to just create a simple radio, I want to know what constitutes it. Thus, I came to a conclusion that understanding how the TDA7000 works internally would satisfy my crave. I did a little research on TDA7000 and came across this fantastic site that put the IC in perspective:

http://cool386.tripod.com/tda7000/tda7000.html

In the data sheet, there is a schematic diagram in which I have no idea how to proceed in reading it. In the website posted above, I came across a block diagram that somewhat simplifies the process, but it's still confusing. I understand that the TDA7000 have a total of 13 circuits - as I can see from the block diagram, please do correct me if I'm wrong- which are:

1. Oscillator
2. Mixer
3. R.F. Input
4. I.F. Amplifier
5. I.F. Selectivity
6. Loop Filter
7. Phase De-Modulator
8. I.F. Amplifier/Limiter
9. Correlator
10. Mute Switch
11. Noise Source
12. Output Amplifier
13. Supply Reference

Right now, all I know about creating a radio is that I must create resonance that matches the frequency I am receiving. I know all about resonance and frequency response as much as Hayt's Engineering Electronics taught me. I know all about transistors and FETs and Op-Amps as Malvino's Electronic Principles taught me.

At the moment I have 6 questions:

1. What are all those circuits?
2. How do they work?
3. Why are they there? Like, how do they contribute in the making of a radio?
4. How do I determine the transfer function of the TDA7000?
5. Is it possible for me to manually create my own TDA7000 with normal electronic components? If so, is it as simple as connecting all those 13 circuits together?
6. As for the schematic in the datasheet, what are the Op-Amps with zener-like symbol on it? For each block of specific circuits like the correlator, what are the AP and the X? What happens to the input from each pin as it enters the IC and exits it? (I'm really sorry for having to ask something like this, but the schematic really does confuses me.)

I'm looking forward to you guys, which are the experts, to guide me, a total noob. May it be from your explanations or directing me to a website that can get me to a good start. I apologize if any of my questions are too vague or unnecessary, or any of my understandings are a bit off. Please correct me so that I may learn.

Thank you for your understanding and patience. I'm looking forward to be a productive member of this community! ^^

#### bertus

Joined Apr 5, 2008
21,324
Hello,

The attached PDF will show you some more about the TDA7000.

Bertus

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#### Audioguru

Joined Dec 20, 2007
11,249
The old TDA7000 is obsolete and is not made anymore. You might find somebody who kept some when they were available. Its performance was awful. It was replaced by the TDA7088 which also has horrible performance. It is available as a copy in China. It tunes stations by scanning across the FM band.

Today you can buy an FM "radio" with a TDA7088, an amplifier, a battery and headphones for $1.00 at The Dollar Store. I was given one. It is overloaded by strong local stations but picks up a few of them (there are MANY stations in my area) if its antenna is shortened. Its sound is distorted. #### absf Joined Dec 29, 2010 1,949 A search on eBay found that there are still a lot of them floating in the market. They are mainly from China and Thailand. Kits is also available for$15+P&P from Thailand.

http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=tda7000&_sacat=0&_from=R40

A local component shop in my area also offers circuit kits (less PCB) for less that \$5 + P&P.

http://www.escol.com.my/Projects.html#Project__06

For learning and experimenting purposes, I dont mind to stock one or two pieces. But I have far better & interesting projects to do than a FM radio.

Allen