HI
Dear Members

I wish to design a FM circuit as follows

1) two frequencies that I use are 1 KH and 250 Hz
The FM circuit will have a output containing 750 Hz, 1kHz and 1.25 KHz

2) A circuit that can extract the 750 Hz signal
3) Another circuit extracting the 1.25 Khz signal

Please help me out.

Thanks and regards
Pratap

 

Since you're dealing with such low frequencies you can try a VCO, a voltage controller oscillator.

Here is a circuit: http://falstad.com/circuit/e-vco.html

 

hai
Thank you for the information
I cant see any circuit in that website
does my IE has any problem or....?

 

can any one suggest a model circuit for example

 

Did you get the circuit showing?

Here's a screenshot of the circuit, anyway.

 

HI
Dear Members

I wish to design a FM circuit as follows

1) two frequencies that I use are 1 KH and 250 Hz
The FM circuit will have a output containing 750 Hz, 1kHz and 1.25 KHz

2) A circuit that can extract the 750 Hz signal
3) Another circuit extracting the 1.25 Khz signal

Please help me out.

Thanks and regards
Pratap

You'll need two oscillators - one at 1K and one at 250 Hz

You'll need to mix the two then filter out the resulting 750H and 1.25K with audio bandpass filters.

Shouldn't be too hard to do.

Rough part is what frequency do you expect to modulate these frequencies with?

Can you provide some sort of explanation as to what the circuit is designed to do when it's completed?

 

You'll need two oscillators - one at 1K and one at 250 Hz

You'll need to mix the two then filter out the resulting 750H and 1.25K with audio bandpass filters.

Shouldn't be too hard to do.

Rough part is what frequency do you expect to modulate these frequencies with?

Can you provide some sort of explanation as to what the circuit is designed to do when it's completed?

hai
this circuit is for biomolecules detection using PHR sensor
1 KHz is frenquency with which dc bias field is supplied
250 Hz is used to produce ac magnetic field
these 2 mix and as you saw in spectral analysis the o/p consists of those freq components.
i need to extract 750 Hz and 1.25 KHz compoenent separately to analysis

 

Yes, so design bandpass filters with sharp slopes at those frequencies.