FM receiver schematic TDA7000 with continuous scan loop - Page 1
Forum section: electronics / projects

author: brickman7
author_rank: Contributor
timestamp: October 01, 2013, 05:40:23 am
content: New to electronics design, computer tech needs a schematic based on the simple TDA7000 icto continuously scan through the frequencies! I have the TDA7000s, and YDA9088s but theyare surface mounts. I can get most older ICs from a supplier in China so I'll takesuggestions. I just need it as simple as possible. I have TDA2822s for amps, but I canget what is needed.I just need an fm scanner to scan thru the frequencies and not lock on a station withouthaving to be reset to continue scanning. And output thru an earphone and speaker. Also, Ido not want to mute the scanning.Certain things I need:1) Scan at 200ms2) Scan 88mHz - 108mHz and loop3) Ability to hear the "white noise" as it's scanning4) Not lock on any frequencyI really need your help!!Thanks!Mason Burns

author: dannyf
author_rank: Super Contributor
timestamp: October 01, 2013, 11:36:12 am
content: "Certain things I need:"How do you know that those are even feasible?

author: brickman7
author_rank: Contributor
timestamp: October 01, 2013, 07:43:11 pm
content: I have a device that can do this, but it scans from 76 to 108 and I need scan 88mHz to 108mHz. And the device I have is way over my head!Thanks

author: free_electron
author_rank: Super Contributor
timestamp: October 01, 2013, 07:52:08 pm
content: not with a tda7000. it cannot scan that fast. in fact it cant scan at all.and then there is the dreaded ' but it is surface mount'.. sorry bub. it's 2013 , almost 2014..DIP : Dinosaur In Package ...

author: brickman7
author_rank: Contributor
timestamp: October 01, 2013, 08:03:08 pm
content: I never said it was a 7000 in the device. I don't know what it is. I asked for a suggested FM ic. I have soldered surace mounts, but it's a pain. I just want the simplest chip for my purpose. When I found out that the 7000 generates it's own noise, I realized I couldn't use it. I need the true scanning "white noise". I'm asking you guys for help with this.Thanks!

author: mamalala
author_rank: Unknown
timestamp: October 02, 2013, 02:21:12 pm
content: I just hope that this isn't meant to be for some ghostbox crap.... Because they operate on the same principle, just to part the gullible from their money.Greetings,Chris

author: brickman7
author_rank: Contributor
timestamp: October 03, 2013, 06:13:32 am
content: Chris, I asked for help with a electronic problem. What I choose to do with it, unless I'm using it unlawfully or immoral, shouldn't matter. If you don't care to help someone with an electronic question or circuit, based on a bias that people, a hundred years ago, had for the type of people on this forum, then don't. I'm a college educated, 56 year old man, that knows what is and what isn't real. I dwell on facts, not on others opinions, I have an open mind, and I am most definitely not gullible. Have you ever used a ghost box, have you even seen one? If you haven't, how can you make that statement? And, if you are closed-minded, how can you ever create anything new, anything ground breaking, anything except a copy. Open your mind! Help me if you want to or don't help me. Someone will!This is for me only, not to make a damn dime, but I'd pay for help, just not from you!Hey, it's all based on electricity!!!!!!Peace!!

author: madsci
author_rank: Regular Contributor
timestamp: October 03, 2013, 06:39:21 am
content: Scanning the entire FM broadcast band in 200ms is the tricky part. You *might* be able to find some programmable VHF scanners that can do itif and only ifyou program it to scan in 200kHz blocks like a normal tuner would. With those large steps, it has to scan far fewer frequencies.Most FM tuner ICs generate their own noise. The TDA 7000 noise source can be disabled by directly connecting pin 3 to the supply rail. The scanning is done by an MCU controlling the front end.It sounds like you need an FM tuner with a varactor based front end and a custom controller to me.SMD is not that hard, especially the larger pitch SOIC packages. All the cool stuff is SMD now. I have soldered a couple of 0.8mm pitch 64 pin VFD controllers using nothing more than a rat shack 40W iron and some wick to clean up the occasional excess. Arealsoldering iron with a tip optimized for drag soldering makes it a much more enjoyable experience and enables hand soldering of truly dense stuff like 304 pin QFPs. There are some excellent videos on youtube of people soldering by hand much larger pin count ICs.Here's a good one....

author: kripton2035
author_rank: Super Contributor
timestamp: October 03, 2013, 07:47:01 am
content: you should play with that :http://dx.com/p/tea5767-fm-radio-module-green-70-108mhz-239086

author: brickman7
author_rank: Contributor
timestamp: October 05, 2013, 01:00:58 am
content: Does anyone know if this interface can be used to control the onboard FM ic chip?ATmega16 ATmeg?a32 TEA5767 TDA1308 ISP 5V FM Radio AVR Development Board MCUAlso, how did you paste that jpg in your post?

author: dannyf
author_rank: Super Contributor
timestamp: October 05, 2013, 01:58:57 am
content: QuoteEven if it can, does it do what you want?

author: madsci
author_rank: Regular Contributor
timestamp: October 06, 2013, 02:52:35 am
content: If it has the needed bus, it should work. I'm not really all that familiar with MCUs but I bet any decent 16 bit MCU that supports the bus on the tuner you wish to control would work. Consult the datasheet for the required bus.Here's a module that has the tuner module and a compatible MCU all on the same board and it's probably the one you were talking about:http://dx.com/p/tea5767-fm-radio-development-board-red-217561?tc=USD&gclid=CLOjptiWgboCFbBDMgodFCEAdgWith that said, that little tuner module may or may not do what you want, especially if you need noiseless between station tuning.Consult the datasheetfor the chip on the tuner to see if you can send it a command to mute the noise source. You will need to edit the firmware code to turn it off if possible. Scanning wise, you send it a command to change frequency, it does it.Most engineers think in terms of high level block diagrams and then consult datasheets for the details on how to put it all together. The datasheet will tell you if the product fits into your design goals.All the TDA7000 advice I gave you was straight from the datasheet.Since you're new to electronics, I give you the most important piece of design advice: The datasheet is your friend.

author: brickman7
author_rank: Contributor
timestamp: October 06, 2013, 08:48:35 am
content: Thanks madsci, that's just like the one I asked about....I ordered one...slow boat from china ya know...but from what I read from the datasheet it may be a gift from above....i just don't know about the scan speed..it has a soft mute that can be turned off and on.....I still don't under stand clearly about white noise and why I have to hear it...I really have never scanned at 200ms without it, hell I might not even need it.I don't understand why or how what I "do" with scanning FM at 200ms works, I just know it does. I'm a sane old man, rational, practical, everything was black and white and I had to see to believe. But that changed 3 months ago and turned my whole frickin' world upside down. I wish I had never stumbled on this crap but now it consumes my every waking thought!Thanks for the advice!

author: brickman7
author_rank: Contributor
timestamp: October 06, 2013, 04:00:56 pm
content: Quote from: dannyf on October 05, 2013, 01:58:57 amThat's the reason I asked the question...can it control the ic!

author: madsci
author_rank: Regular Contributor
timestamp: October 06, 2013, 10:48:39 pm
content: The bus interface is the *only* way to send the IC commands from the most basic tuning to more advanced capabilities like FM Muting and FM Stereo.The one with the MCU on board *will* control itif and only ifyou program it properly.Some links to get you started:http://ssihla.wordpress.com/2012/07/17/making-an-fm-radio-part-1-the-tea5767/] http://ssihla.wordpress.com/2012/07/17/making-an-fm-radio-part-1-the-tea5767/http://www.instructables.com/id/TEA5767-FM-Radio-Breakout-Board-for-Arduino/?ALLSTEPSThe big one...complete with some cool shots of the demo board software!http://frrl.files.wordpress.com/2009/02/application_note_tea5767-8.pdfI will be fairly useless on the software side of things I'm afraid. Hopefully the code snippets provided give you some insight. The Arduino community seems to like these little things a lot.While I have a pretty good idea what this is for, I really do not care what you use it for as long as it's not harmful to others. Interpreting the data from this little gizmo you're making is all up to you. I guess one man's spurious emissions is another man's ethereal being? For the record, I don't believe insoulslet alone other, more grandiose spiritual beings but this is an electronics forum and I'm here to help with the electronics themselves.I've had a radio project in mind, sadly I don't know enough yet to make the thing nor do I have time to. I want a sort of "universal" receiver. 100kHz to about 870Mhz with specific decoders for various things like FM stereo, AM Stereo, RDS, SCA, and various digital modes of importance to hams. Realistically, I'm looking at several radios in a box controlled via a common MCU. Picked up some PSK31 or AFSK? See it right on the front panel! Too bad HD Radio is proprietary. For a one off unit I could probably grab a module and switch it in and out of circuit for HD. (for conventional FM, the unit would use a *real* VHF receiver and feed the output into a stereo demodulator.)

author: dannyf
author_rank: Super Contributor
timestamp: October 06, 2013, 11:15:10 pm
content: Sillab has a few dsp based radios: very simple (rf) setup.But they are for broadcast bands only.

author: brickman7
author_rank: Contributor
timestamp: October 08, 2013, 01:36:32 am
content: Thanks Madsci....I appreciate your help!!Mason