TDA7000 questions

Discussion in 'The Projects Forum' started by hadoque, Jul 27, 2007.

  1. hadoque

    Thread Starter Member

    Jul 24, 2007
    So, my next project is to build a FM-reciever based on the TDA7000. Now I have some questions about that cirquit diagram aswell (7th page in attached datasheet).
    The circle with a wave marked f_rf and EMF, thats the antenna, right?
    The a.f output, thats the audio output, right? If i connect the anode of a loudspeaker to the output, do I connect the cathode to the ground?
    Only the power input of the circuit is marked, do i connect the output to the ground aswell?

    thanks a lot

    by the way, what do these abbreviations (f_rf, EMF and a.f) mean?
  2. BrianH

    Active Member

    Mar 21, 2007
    Hello there,

    The connection marked frf is your RF input to the IC which as you say, could be an antenna input.
    The AF output is your audio output as you've already suggested but I think you've become a little confused about the speaker. There are no anode/cathode connections on a speaker. There are positive and negative connecitons, and you'd want to connect the AF output to the positive side of the speaker, and the analog ground to the negative side. If you connect the speaker the wrong way around it's not really of any great consequence, it just means the sound will be 180degrees out of phase. The ear is pretty insensitive to changes in phase, you'll find it very difficult to hear the difference in a speaker connected the wrong way around, provided ALL the speakers in the system are connected the same way. So you can get them wrong, as long as you get them all wrong!

    I wouldn't suggest you connect the AF out of that IC straight to a speaker. I haven't had any dealings with the TDA7000 IC before but I doubt it's capable of driving a low impedance load like a speaker. You'll want an audio amplifier in between the output of the IC and your speaker.

  3. hadoque

    Thread Starter Member

    Jul 24, 2007
    ok, thanks alot for the help. I'll return with a progressreport. ;)