Sine wave generator from AM radio receiver

[linkaiyu]

Hi,

i'm working on a simple small signal amplifier as my bachelor thesis. The goal is be the pcb.
During the presentation i would like to demonstrate the functioning by using arduino but i need
a pure sine wave signal to feed the amplifier.
I studied the theory abt radio transmissions, and correct me if i'm wrong, the AM radio receiver should
incorporate a frequency variable device.
The question is: can i rip off that device (if there is any) from a AM receiver and use it as my sine wave generator?  XD

[retrolefty]

Hi,

i'm working on a simple small signal amplifier as my bachelor thesis. The goal is be the pcb.
During the presentation i would like to demonstrate the functioning by using arduino but i need
a pure sine wave signal to feed the amplifier.
I studied the theory abt radio transmissions, and correct me if i'm wrong, the AM radio receiver should
incorporate a frequency variable device.
The question is: can i rip off that device (if there is any) from a AM receiver and use it as my sine wave generator?  XD

Not likely, modern AM radios use 'local' oscillator that is intergrated along with most of the other AM radio functions into a single chip. Plus the frequency of the AM local oscillator is well above the hearing range of humans.

It's not too hard to generate a sine wave from a Arduino timer output and pass it through a simple resistor/capacitor low pass filter. Check out the Tone library for creating audio frequencies with an arduino.

[Grumpy_Mike]

No.
Look in the playground for an arduino sin wave generator.

[linkaiyu]

Thanks. I'll take a look to both XD

[Drmn4ea]

Hi,
It might be overkill and/or not fast enough for your needs, but I posted an approach a little while ago for an arbitrary amplitude + arbitrary waveform generator implemented purely in software: http://arduino.cc/forum/index.php/topic,63604.0.html .

For a one-off project, it's probably easier to follow retrolefty's suggestion of generating a squarewave (tone()) and filtering it. VCO (voltage controlled oscillator) circuits are fun to play with too if you have the time; this may give you a more consistent signal over the entire audio frequency range (won't have to worry about rolloff from the squarewave-filter).

[robtillaart]

What should be the frequency range of the sine generator?

[linkaiyu]

i'm using the LM318 and a bilateral current pump configuration.
The bandwidth is 1MHz, but since i need the VOC just for a little dimostration, some kHz are also good
thank you