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How to modulate a carrier wave with audio (10 - Oscillators)
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- เผยแพร่เมื่อ 12 ส.ค. 2024
- How to build a simple AM radio transmitter using a Colpitts oscillator and an audio signal source. Here I show how to modulate an RF carrier wave with an audio tone.
Aaron Danner is a professor in the Department of Electrical and Computer Engineering at the National University of Singapore.
danner.group
Video filmed and edited by Cheryl Lim.
@randomcheryl
Watched the whole series! Never understood how AM and FM works as good as I do now! Thank you prof.
Would love to see part 11
I just built an old school transmitter using a screen-modulated 6888 vacuum tube (and a few others).
it works :) I have quite stable 1.14064 MHz here
Absolutely brilliant.
Every second I learn as much as I would in hours.
Great series of videos, I'm reviewing this interesting topic from college just for hobby (I'm an electrical and electronics engineer), I like how you approach theory and practice. Continue doing this!
Thank you very much ❤
Thanks for that great video. We are looking forward to the next videos.
Awsome. Great channel!
Welcome aboard!
thank you prof we wait am modulator video please don't late.
Yeah
Great videos. Really helpful stuff. Would love to see a receiver for this tho!🙏🏾
I love it
Great simply great , awesome , explanation is simple , easy to understand . Sir a request , if possible please make a video on the RC circuitry used for RC controlled car. How the signal is transmitted from transmitter to receiver module's to control the dc or servo motor of the RC toy car , please consider it as a project
Teach us from the scratch , step by step Circuit designing etc
Any magazine or book name having this kind of RC toys projects , with detail explanation of the schematic
Thanks 😁
Thanks
@adanner Which opamp models did you use?
Where can i find video 11?
That was a great explaination and topic! I succeded in building the Colpitts oscillator and modulating it with an audio source coming from my pc. I have very small range of about 3 feet. I would like to understand how to increase the transmitting distance, i tried by putting an antenna and by increasing the collector current of the bjt but the results where not enough. Moreover i noticed that by using smaller inductors to produce higher frequencies, the output of the colpitts reduces and i get lower and lower peak to peak voltages of the sine wave. Can anyone explain me why is that happening and how to increase effectively the transmitting distance? Thanks🙏
With rf power amp to output
an impedence matched antenna, an rf amplifier, etc etc
My Colpitts oscillator produces a waveform that looks like a cursive lowercase r. Help!
Your transistor is probably cutting of, also thats not good for efficiency (also at a higher power you would get in trouble) because of the other frequencies that you are generating. Try switching around some resistors (or use potentiometers) to get it to a pure sine. Also doing that will reduce the amplitude, wich youll have to compensate for in another way.
Also if you can, try looking at it with a spectrum analyzer but be careful that you dont destroy the input of it.
Could this work at 1GHz?
It's harder. The design still works but you have to be careful to keep the wires really short (their inductance matters then due to the short wavelength of the signal) and choose components that don't have excessive parasitic capacitance.
What is the point of showing the schematic for one second?!
Well if you paused the video you'd see that is nothing different from the schematic you have seen already