walters said:
I think the mixer/oscillator in a Radio is actaully a AM modulator chip...
I don't think there is such thing as an AM modulator chip. If there was, then young kids with some electronic knowledge could make transmitters and potentially screw up the entire neighbourhood :lol:
a mixer=modulator i guess
Not really.
A mixer takes two analog signals and combines them to produce one output signal.
A modulator (especially when dealing with AM and FM) takes an analog signal, and outputs the same signal at a different frequency.
Modulators:
- Diode used as modulator (there are many variations of this)
Two diodes back-to-back are common. Better known as a transistor modulator.
- voltage controlled amplifier circuit (use video signal as the control voltage)
Many modulators are voltage controlled oscillators.
- voltage or current controlled attenuator (transistor, fet or diode based)
I think the only use for an attenuator is to make the signal more clear. Other than that, it will hinder the range of the receiver, or hinder the transmitters range.
Resistors make perfect attenuators :wink:
- special mixer IC circuit (analogue multiplier)
You could make a simple mixer. Take two resistors and connect one end of each one together. The tied (connected) ends make an output, and the untied ends make the inputs to each signal.
Does the data sheets for AM modulators show a schematic of whats inside a AM modulator?
You will be lucky if you find any, and if you do, you will find a datasheet on an IC that helps form the modulator. If you want a schematic, search google for "transistor transmitter".
how does it produce the AM modulation waveform?
AM = amplitude modulation. Amplitude = volume. so basically, the volume (amplitude) changes when the input to the modulator changes.
With FM, the frequency of the waveform changes when the input changes. I find it better altering the frequency rather than the amplitude, because the amplitude has a higher effect on gain. This explains why AM is terrible.
I see the carrier frequency...
Can I have your eyes? :shock: :lol:
We can't see the carrier frequency directly. LOL
i don't understand about the AM modulation waveform how it creates thats sort of modulation
I explained it above.
...VCO makes this type of modulation...
VCO = Voltage controlled oscillator.
As it states, the oscillator changes with respect to the input voltage. They can help you achieve FM modulation because oscillators produce frequency, and in a VCO, changing the voltage can change the frequency.
how does this modulator chip create that "Bubble shape" around the carrier frequency?
The best way to learn is to not depend on multi-functional chips. In fact, start with transistors.
Try this circuit. It is an FM transmitter.
**broken link removed**
Also, talkingelectronics.com has alot of info about FM transmitters.