1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

TDA7000 receiver project

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by zachtheterrible, Oct 7, 2004.

  1. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,595
    Likes:
    952
    Location:
    Canada, of course!
    Hi Zach,
    A good radio is very complicated. It needs special parts and probably special test equipment to align it.
    When I was young there were kits for anything, including test equipment, very good radios and even a colour TV. Today those complicated-kit manufacturers are gone.

    If you could find those special parts, they would cost much more than a good manufactured radio.

    For years I have had a tiny, FM stereo radio (no speakers, headphones only). It was inexpensive and works very well. It's a Sony walkman. There is a whole website out there that is devoted to making them sound better. One suggested mod was to add bigger output caps, the circuit board layout is designed for them. They figured that Sony saved themselves maybe only $.20 for each radio on that goof-up. With bigger caps, they say the bass is really awesome.
    I didn't mod mine. In fact, I have never even looked inside. It works very well the way it was made.
     
  2. zachtheterrible

    zachtheterrible Active Member

    Joined:
    May 4, 2004
    Messages:
    2,154
    Likes:
    2
    Location:
    California, USA
    sigh :(

    i bought and built that radio for nothing :cry: . i was thinkin that this would be an EXTREMELY good, sensitive radio, but, ah well.

    i guess ill just have to go to wallmart, buy a couple radios and test them out, and then return the ones that i don't want.

    One thing that i want to be able to do is change the frequency from the regular radio band 88-108 down to like 70, 60, etc. which i could do very easily w/ the TDA7000. I guess that it can be done with a storebought radio though.
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    I only ever built one valve (tube) item, that was a small single ended amplifier when I was a kid back in the 60's. It used a 6BW6 output valve, and an EF80 preamp, with a metal rectifer. Most of the parts came out of scrap TV's, there used to be a rubbish tip about 20 minutes walk away from my parents house - I used to get all my bits from there :lol:

    The tip was a great place as a kid, we used to make bikes out of thrown away parts, and huge karts with pram wheels - I think the biggest was about 12 wheels :lol: Considering we used to ride them down a 1 in 6 hill, actually down the main street of the village, it's a good job there wasn't much traffic back then!.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,595
    Likes:
    952
    Location:
    Canada, of course!

    Hi Nigel,
    Yeah, there are also steep hills in Vancouver, Canada where I grew up.
    One seemed like 1 in 1, but probably wasn't that steep.
    I was roaring down in my DIY kart, then I saw a big truck (lorry?) coming up the hill toward me. When I turned the steering a front wheel came off my kart and after many sparks I got stuck under the truck. I ducked my head down just at the right time. (Scraped my back a bit on the truck's underthings).

    Have you ever poked around with an FM, uh, SCA sxxcast I think (can't remember what the subcarrier is called) that was used for restaurant music? Some stations transmitted other neat stuff up there like instructions to their field crew, weather forcasts, etc.

    Hi Zach,
    Your radio shouldn't be bad, it has good reviews all over the web. Maybe it just needs a proper PCB instead of Veroboard.

    What interests you down at 70MHz? The only things that I've heard near there are wireless mics used by amateur singers and fitness instructors, and wireless boardroom-table mics.
    I was installing those boardroom-table conference mic systems. I souped them up so that they sounded crisp and clear (+10dB peak at 3KHz, don't tell the telco). When a major insurance company found out that they were transmitting their secrets to their competitors across the street, I quickly made them a scrambler.

    First I made a single-sideband, suppressed carrier scrambler from a balanced modulator IC, and simply repeated it at the receiver. The brass at the insurance company were really impressed. I put scramblers in two of their wireless boardroom-table mics. At their next important conference with their shareholders, the mics sounded like they were slowly drifting in and out of phase. They were! An executive would sound nice and loud at first, then it sounded like he was walking away, then coming back. I quickly turned off one of the mics and the conference proceeded alright.

    Having no way to syncronise the scramblers, I changed the scrambling method to AM, single inverted sideband. Low audio frequencies were converted to high frequencies and high audio frequencies to low. Pretty good scrambling. It worked well.

    The insurance company went bankrupt and lost their brand-new palace and conference system, because it turned-out that they cheated their shareholders. Maybe their competitors across the street heard their secrets and cheating before my scrambler was installed, and blew the whistle on them.

    Lots of fun with FM.
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    I've only ever heard it mentioned in the USA, I don't think it was ever used in the UK?.
     
  7. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,595
    Likes:
    952
    Location:
    Canada, of course!
  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    They often used to use looped tapes, there was a company which specialised in such music and leased the equipment.

    But in pubs you often don't have background music, but there's often a jukebox.

    Live music in pubs is a big issue at the moment over here, government changes have made it very expensive for a pub to have more than a duo playing - unless it includes 'Morris Dancers' - bizarre or what?.
     
  9. John Sorensen

    John Sorensen New Member

    Joined:
    May 17, 2003
    Messages:
    320
    Likes:
    0
    Location:
    Montana, USA
    C'mon, you made that up!

    j.
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    I'm afraid not!.

    Morris dancing is a reasonably common occurance at some UK pubs, as the new regulations would have banned more than two of them - the law was amended to allow them!.

    I would personally like to disassociate myself from any connection with Morris dancers what so ever! - I would drive past a pub where they were performing!.
     
  11. zevon8

    zevon8 New Member

    Joined:
    Apr 10, 2004
    Messages:
    917
    Likes:
    2
    Location:
    Toronto, Canada, eh
    SCA broadcasts are big business here in Canada. Well, the recievers are anyways. :D Mostly in larger urban centres, they are used for Mulitcultural radio stations, repeat brodcasts of foreign radio stations, etc. Many smaller shops sell radios that have a small filter circuit inserted to receive the sidebands with a regular FM radio. They charge about $70 for what is a $20 dollar portable with $5 in parts added. Mostly the radios are really poor quality, so the stages are still descrete and easier to modify. I'm not knocking the business, it just the end product radio is pretty bad.

    Musak was distributed here that way before, but now most larger stores use their sattelite datalinks, and play preprogrammed source from head-office. Custom commercials and everything.
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    Yes, it's done by satellite here as well, Asda (a large supermarket chain, now owned by Walmart) have their own satellite radio station - as have others.
     
  13. zachtheterrible

    zachtheterrible Active Member

    Joined:
    May 4, 2004
    Messages:
    2,154
    Likes:
    2
    Location:
    California, USA
    yeah, maybe it does need to be done on PCB. i'm gonna be buying some supplies for rthat shortly.

    i want to go down (or above) the regular radio stations so i dont have to compete with the other stations :evil: . oh yeah, and somewhere down there, i can hear the CBS tv station. oh yeah (again), when i was fiddlin around, i heard something like a modem with tones. what could that be?
     
  14. gerty

    gerty Member

    Joined:
    Mar 23, 2004
    Messages:
    563
    Likes:
    4
    Location:
    Tennessee
    Zach maybe this'll help.. (if you can get by all the ads)
    http://electronics.howstuffworks.com/radio-spectrum1.htm
    It has a listing of radio frequency ranges to give you an idea of what you might hear in a specific range..
    Another place is cityfreq.com for public/private service radio frequencies
     
  15. zachtheterrible

    zachtheterrible Active Member

    Joined:
    May 4, 2004
    Messages:
    2,154
    Likes:
    2
    Location:
    California, USA
    thanx very much gerty. cityfreq.com is pretty cool :lol:
     
  16. -=GST=- Nemisis (cs/cz)

    -=GST=- Nemisis (cs/cz) New Member

    Joined:
    Aug 27, 2004
    Messages:
    178
    Likes:
    0
    i posted my design a while back, page 5 i think and i have been away for a while but i think zach said that the telescopic antenna wouldnt be as good as a dipole one, well can anyone help me make a tda7000 schemiatic that uses a dipole and i know how long it is and i know how long the coils have to be and it will get clear reception in the UK?
     
  17. zachtheterrible

    zachtheterrible Active Member

    Joined:
    May 4, 2004
    Messages:
    2,154
    Likes:
    2
    Location:
    California, USA
    a telescopic antenna might work just fine for you if you just simply want to listn to the radio. I was saying that a mounted, correctly constructed antenna would give you the best sensitivity you can get (but of course you cant go carrying one of those things around). The reason i went with the big antenna was i needed major sensitivity because I want to be able to pick up a tiny bug. When I first made the receiver, it was working fine, but lately, it seems to be drifting in and out of working good and not working good. I am going to make a PCB version in the next couple of weeks (its on veroboard right now) so hopefully i can get it to work better.
     
  18. stevez

    stevez Active Member

    Joined:
    Apr 3, 2003
    Messages:
    2,133
    Likes:
    9
    Location:
    Rochester, NY
    This thread is so long I almost forgot what it was about.

    "Below" the FM band are TV channels 2 thru 7 as well as other services so you might have been hearing TV. Just above FM band is aircraft - be careful if you are any where near an airport. I know at the low end of the aircraft band (upper end of FM) are airport weather conditions and other similar broadcasts. Interfere with those and someone will be visiting you for sure.

    Not sure if I've mentioned it - long antennas do help with reception however it can also present signals at the front end of a receiver that are so strong that it overpowers the receiver. This is especially true of simpler receivers that might perform well way out in the country. Bring them into a metropolitan area where RF levels are high and they can't sort out one signal from another.
     
  19. maboyz

    maboyz New Member

    Joined:
    Oct 7, 2005
    Messages:
    1
    Likes:
    0
    tda7000 fm receiver

    Hi gentleman and the ladies out there. I've just joined in this forum. Can somebody help me with information as to, how to display the tuned in frequency on the tda7000 reciever.
     
  20. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
    Messages:
    39,331
    Likes:
    653
    Location:
    Derbyshire, UK
    Re: tda7000 fm receiver

    You use a mechanical pointer that moves along a scale operated by a 'dial drive cord' from the tuning capacitor - as radios have for 75 years or so.

    I suspect trying to add digital readout wouldn't be worth while?, you may as well build a 'proper' radio and add it to that instead.
     
  21. zachtheterrible

    zachtheterrible Active Member

    Joined:
    May 4, 2004
    Messages:
    2,154
    Likes:
    2
    Location:
    California, USA
    Re: tda7000 fm receiver

    You must've really went digging to bring this old topic up again :lol:
    The TDA7000 is not worth your time. The reception that I got with it was about as good as a clock radio, even with a very good antenna.

    Maybe you'll have better luck than I :wink:
     

Share This Page