Amplitude Modulation tutorial and AM radio transmitter circuit
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange users cite it as the source of a simple op-amp AM transmitter circuit when asking how its oscillator, mixer or filter stages actually work.
Recommended by 0 people across 0 different months, 2013 to 2021.
What it is
A short tutorial from Afrotechmods that covers the history of radio waves, explains modulation and amplitude modulation, and then walks through building a low-power AM radio transmitter. The build uses an op-amp relaxation oscillator as the carrier source plus a mixer stage for the audio.
What people said
Cites superkittens · 2013-06 · Electrical Engineering Stack Exchange · on “AM Modulator Mixer Circuit”
I found a very basic AM transmitter circuit on the youtube video here [this video] . The schematic is below: I'm a bit confused on the op-amp circuit on the right. It seems that the op-amp is really only taking the difference between the message and carrier signals - not multiplying them together like it should be doing. I'm not at all convinced that this part of the circuit is a frequency mixer. Am I just crazy?
Cites mickkk · 2016-08 · Electrical Engineering Stack Exchange · on “Oscillator circuit with TL071 opAmp for amateur very short range AM radio”
I stumbled upon this nice video [this video] and thought I'd try to reproduce the experiment. Basically the video shows how to build an AM transmitter circuit using an opamp, some resistors and a capacitor. This is the circuit schematics for the oscillator that should generate the carrier wave: simulate this circuit [LINK] – Schematic created using CircuitLab [LINK] The carrier wave should be at the OUT node right? My problem is that I do not understand how can this circuit oscillate since it is getting constant voltages as input and the video does not say anything about any function generator. My guess is that instead of 9 Volts in the voltage divider I should use a function generator with the c
Cites fahad shaikh · 2016-09 · Electrical Engineering Stack Exchange · on “Output of Oscillator and Modulator is Absent”
I am designing circuit of AM transmitter. This circuit I got from youtube. You can have it from here [this video] [LINK] I designed the same circuit in proteus and simulate it and try to obtain different waveforms on Oscilloscope. I got input wave of mp3 player but there is no high frequency carrier wave(Oscillator generated wave) and modulated wave. [LINK] I am beginner in proteus so its bit difficult to understand the problem.
Cites Israr · 2021-06 · Electrical Engineering Stack Exchange · on “Amplitude modulation using microcntroller”
I have found this circuit diagram for amplitude modulation here [this video] . [LINK] Only difference is, the output of modulated signal will be fed to a push-pull transformer. The message signals to be modulated are standard waveforms which may come from microcontroller. Secondly I can create the carrier signal from a microcontroller as well. I have a rough idea about the circuit as below: [LINK] All 3 signals can be created by a microcontroller. Current to be supplied in probes is less than 100mA. Carrier Frequency is 10KHz. Signal Frequency is 1 to 150Hz. My questions are: Can I avoid some or all of the analog circuit shown above? Is there any diffrence in the final modulated signal if created
Cites Dat · 2021-07 · Electrical Engineering Stack Exchange · on “How is this high pass filter?”
I am new to electronics. I am watching this video. [this video] At 5:48, you can see the high pass filter: [LINK] I understand the high pass filter, look at this: [LINK] Then, I thought the first circuit should be like this: [LINK] Do I misunderstand anything?
Cites Dat · 2021-07 · Electrical Engineering Stack Exchange · on “How does this circuit generate a high frequency signal?”
I am new to electronics. I am watching this video. [this video] At 5:37, you can see the first half of the circuit generate a high frequency signal. How do an op-amp, 9 VDC, and a few resistors generate a high frequency signal? [LINK]