88. AM Radio Oscillator and Mixer

Ғылым және технология

This is the final section of the Elenco AM radio (FM to follow). Testing and tuning if the oscillator and antenna section are completed along with a overall system test.
There is a mistake in the capacitance claculation - it should be
1/((1/C1)+(1/C2)...)
I did find the oscillation problem - it was the audio amp itself. I replaced it with the transistor amp, and voila, no oscillation.

Пікірлер: 29

  • @nicktesla4466
    @nicktesla44664 жыл бұрын

    You are the only person on KZread explaining this, thank you so much.

  • @deltagold9646
    @deltagold96464 жыл бұрын

    Thank you for making the corrections needed in the Elenco circuit ! Great videos Sir ! Thumbs up !

  • @longjohn526
    @longjohn5265 ай бұрын

    I built one of these in school about 35 years ago ..... As soon as I finished and got it graded I tore out the ferrite loopstick and replaced it with a coil wound on a 35mm Film can put a 10 ft piece of wire on it for an antenna and could pull in a fairly large portion of the SW bands (if I remember right 60M 49M and 40M. It was pretty fiddly to tune and the image rejection wasn't very good but it could pull in the strong stations

  • @BobMellor1954
    @BobMellor19543 жыл бұрын

    Great AM explanations in much needed detail, thank you

  • @facebook5546
    @facebook55464 жыл бұрын

    You are the best channel. Thank you for your work !

  • @overengineeredinoz7683
    @overengineeredinoz76832 жыл бұрын

    Thankyou. Such a great explanation of what is going on.

  • @silvanocalza8180
    @silvanocalza81804 жыл бұрын

    Wonderful videos, Thank you for your work

  • @TheLightBeacon
    @TheLightBeacon2 жыл бұрын

    The AM Radio Series playlist is backwards in order, but it's great!

  • @kurchak

    @kurchak

    2 жыл бұрын

    It may seem that way, but he did it in the order the kit has you do it. They start on the audio amp and work their way back to the antenna. This is helpful because you can start "hearing" your tests right away and throughout the entire process. For example, if they started on the antenna and had no IF amps or audio amps or anything then testing the antenna would be much more difficult (and boring). It's almost necessary to work in this direction.

  • @TheLightBeacon

    @TheLightBeacon

    2 жыл бұрын

    ​@@kurchak He did the videos in the order according to the kit (I agree - it is a more useful order), but the AM playlist is backwards from how he numbered the videos. Is there a way to comment on a playlist, not individual videos?

  • @kurchak

    @kurchak

    2 жыл бұрын

    @@TheLightBeacon oh are they? Oops lol. I didn't even notice that. Probably because I didn't watch it through like that. Yeah that would be annoying for sure lol

  • @davidluther3408
    @davidluther34084 жыл бұрын

    GOOD DEMONTRATION.I HAVE MANY QUESTIONS ON THIS ALIGHNMENT PROCEDURE BUT,DO NOT NO WHERE TO BEGIN.MAY I SUGGEST A PRESENTATION ON LOG OP AMPS IF YOU HAVE TIME.

  • @deltagold9646
    @deltagold96464 жыл бұрын

    Hello Mr. Volt, thank you. Would you please clarify what your note about the capacitor is @ 5:53 ? In the Fm portion, what other discrepancies would need to be corrected ?

  • @dwtees
    @dwtees3 ай бұрын

    I'm a little confused. You say at around 2.22 the pulse comes out of the collector. It appears to me the flow of the current is from 9v through R34 (which there will be a voltage drop) then to the collector through emitter though R33 to ground. You state the pulse comes out of the collector but it looks to me the pulse is produced by the voltage drop across R34. Saying the pulse comes out of the collector makes the current go the wrong way to me and doesn't make sense but I am surely no engineer. I see that there will be a pulse at the collector. Its just confuses me saying the pulse comes out of the collector. It looks like the pulse will be going "into" the collector resulting in a voltage drop across R34 and R33 with the pulse going through the primary of L5 resulting in an inductive kick which is amplified though more windings in the secondary of L5 then onward through the rest of the circuitry. Are you just saving time so you won't have to waste words tracing the current flow through all the resistors and oscillator transformer and coils?? I'm currently building this kit. Thank for your video and how to tweak things.

  • @uwepolifka4583
    @uwepolifka45834 жыл бұрын

    I got one of the Elenco radio kits two weeks ago. The kit itself is nice but the plan is squeezed and pressed so much, maybe to save some white surface, that it looks like a gordic knot.

  • @lewisdaniels4228
    @lewisdaniels4228 Жыл бұрын

    @ 19:02, I believe those four frequencies in the example (1 MHz, 1.455 MHz, 22.455 MHz, 455 MHz) are actually electrical currents. Are these four electrical currents passing through the Collector (mixer-oscillator transistor) at the same time?

  • @user-uv7ug1du4n
    @user-uv7ug1du4n3 жыл бұрын

    Nice posting. I don't understand why the connection point of C-28 and variable capacitors is not grounded in circuit diagram?

  • @markrhine5809
    @markrhine58092 жыл бұрын

    Hi, Great video, question, when they say modulate at 1K hz at 80% modulation, what does this mean?

  • @worroSfOretsevraH
    @worroSfOretsevraH3 жыл бұрын

    Could you please explain why the inductor has to be adjusted for the lower frequency part of the band, and the capacitor for the higher? Thank you.

  • @naeemhaq3504
    @naeemhaq35044 жыл бұрын

    i liked your videos

  • @mohamedashraf-sv1nc
    @mohamedashraf-sv1nc3 жыл бұрын

    Thank you

  • @TheOffsetVolt

    @TheOffsetVolt

    3 жыл бұрын

    You're welcome

  • @Ahmet_Yilmaz
    @Ahmet_Yilmaz2 жыл бұрын

    Why C28 is connected to VCC instead of GND ?

  • @winhsu3677
    @winhsu36774 жыл бұрын

    so difficult!

  • @keithmaddox1469
    @keithmaddox14692 жыл бұрын

    Wow, way too much bass on the mic. Nice video though.

  • @TheOffsetVolt

    @TheOffsetVolt

    2 жыл бұрын

    Noted!

  • @kurchak

    @kurchak

    2 жыл бұрын

    It sounded good on my phone, but yeah, when I listened in the car it was super bass-y.

  • @naeemhaq3504
    @naeemhaq35044 жыл бұрын

    but please make videos on new topics

  • @louisdesipio3343
    @louisdesipio3343 Жыл бұрын

    how about some real radio stations being heard!

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