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
You are the only person on KZread explaining this, thank you so much.
Thank you for making the corrections needed in the Elenco circuit ! Great videos Sir ! Thumbs up !
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
Great AM explanations in much needed detail, thank you
You are the best channel. Thank you for your work !
Thankyou. Such a great explanation of what is going on.
Wonderful videos, Thank you for your work
The AM Radio Series playlist is backwards in order, but it's great!
@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
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
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
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.
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 ?
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.
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.
@ 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?
Nice posting. I don't understand why the connection point of C-28 and variable capacitors is not grounded in circuit diagram?
Hi, Great video, question, when they say modulate at 1K hz at 80% modulation, what does this mean?
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.
i liked your videos
Thank you
@TheOffsetVolt
3 жыл бұрын
You're welcome
Why C28 is connected to VCC instead of GND ?
so difficult!
Wow, way too much bass on the mic. Nice video though.
@TheOffsetVolt
2 жыл бұрын
Noted!
@kurchak
2 жыл бұрын
It sounded good on my phone, but yeah, when I listened in the car it was super bass-y.
but please make videos on new topics
how about some real radio stations being heard!