Help me get the frequency modulation done in FM transmitter

[satishmalik]

fm tx

dear sir ,i am an engineering student . i have to do a project wherein i have to design a fm transmitter and get the dtmf tones modulated at 10.75 mhz , here 10.75 is the carrier frequency and i have to get the dtmf tones modulated at this frequency . i have tried lots of ccts but getting the frequency modulation done at HF range is still a problem .

if you could help me in desigining a cct (may be some ic based cct ) , i would be very grateful to you sir .

treat matter most urgent .

 

[truebs]

Re: fm tx

Hi,
i've done a similar project on DTMF remote control system.
Please inform me more details about your project.
I used UMB91214 IC as DTMF code generator and 8870 as DTMF to BCD convertor for my project.
MY circuit was quite similar to one shown below :
(but it used KT3170)
**broken link removed**

A number of DTMF Ic's are available in market already.
Please make a search and i don't think it would be a tough job.
You might also find this link useful :
www.geocities.com/constantinescuradu/content/dtmf.htm

See ya !!

 

[bobcat1]

Re: fm tx

Hi

For your application you need to use a Colpitts oscillators with ceramic resonator of 10.7 Mhz in the feedback path.

Search philips site for NE602/612 chip app note and elektor electronics thay have many schematic for this application

All the best

Bobi

 

[satishmalik]

Re: fm tx

Hi,
i've done a similar project on DTMF remote control system.
Please inform me more details about your project.
I used UMB91214 IC as DTMF code generator and 8870 as DTMF to BCD convertor for my project.
MY circuit was quite similar to one shown below :
(but it used KT3170)
h**p://electronicsworld.tripod.com/remotecontrolsimages/remotecontrolsckt2.html

A number of DTMF Ic's are available in market already.
Please make a search and i don't think it would be a tough job.
You might also find this link useful :
www.geocities.com/constantinescuradu/content/dtmf.htm

See ya !!

sir , dtmf ic's you mentioned are available in market which i already have . The problem i am facing is of making a fm transmitter in HF (high frequency range ie 10.75 mhz ). if i can get frequency modulation done at 10.75 mhz than only i will be able to get dtmf tones modulated . hence if you can suggest some ic based circuit for frequncy modulation at 10.75 mhz .
otherwise tahnks a lot for your suggestion regarding dtmf tone ics .