i've tried converting analog audio signals to frquency so that it can be transmitted through light using LED. But the chip RC4151 seems like only converts a DC signal. anyone know of a chip that could convert analog audio signals to frquencr which could handle the high frequency and fast response time

 

Hey Sean, Well, audio signals are already frequencies, so I'm guessing you are wanting to modulate these and transmit them somehow. If I were goin to do it optically, I would probably use infrared components and use the standard 40KHz modulating frequency that is in use by most consumer electronics. You can get your audio frequencies modulated into that by using a 555 timer, using it's output to drive an op-amp, whose output drives an IR(infrared) LED. Then use an IR detector that only passes a band around 40 KHz (Sharp used to make these detectors....and may still...GPX ___ I think)and filter that output so that only your audio frequencies get through the filter. Amplify it, then do whatever you want with it. You can use what little info I gave you here to do an intelligent internet search. Hope this at least gets you on track with some possibilities.

 

Well, I am assuming here that you want to modulate your audio to a higher frequency since it's already in frequency form...

If however you just want to transmit the analog signals without wires, you can either use an infrared diode and then and infrared detector to receive them. It can be done via RF also. You can find all you need at radio shack if you're in USA
including complete to use units for abot $20

If on the other hand you're trying to modulate the audio into a binary frequency pulse, then you'll have to use a VTF or a PWM converter

A cheaper way which is what I suspect you're trying to do is to use a comparator& Op-Amps to Built a PWM circuit.
This will convert that voltage level into a corresponding modulated infrared beam.
Your receiverwill then consist of an integrator like circuit that will convert the pulse circuit back into autio...
Check your library for PWM books

> i've tried converting analog audio signals to frquency so that it can be transmitted through light using LED. But the chip RC4151 seems like only converts a DC signal. anyone know of a chip that could convert analog audio signals to frquencr which could handle the high frequency and fast response time

 

tell me how much frequency you need?(or bitrate)