Headphone jack to antenna jack?

[bobleny]

Hey, can someone tell me how to take the signal from a CD player's headphone jack and plug it into the antenna jack of my car radio?

I'm not looking for a FM transmitter or anything like that. I want to unplug the car antenna, and plug the CD player into it.

Is the headphone jack digital or analog?
Is the antenna jack digital or analog?

That's all I need to know right now. I hope they are both analog...

Thanks for you help!

 

[Hero999]

It's not a case of digital or analogue, both the headphone and antenna jack are analogue.

The headphone jack output is audio frequency and is a direct electrical copy of the sound wave, the antenna socket is VHF (Very High Frequency, assuming it's FM), frequency modulation.

You need an FM modulator to connect the headphone jack to the antenna socket: an FM transmitter is an FM modulator.

If you don't want to transmit the signal through the air, you can connect the transmitter to the antenna jack via an attenuator (just a couple of resistors) and coaxial cable.

 

[bobleny]

Yeah OK, I new there was something different about the two.
What is the attenuator for? I'm mean, I know what it does, but why do I need it?
Does anyone have any diagrams / schematics? I checked the project section and they seem to all be wireless modulators.
Are there any ICs out there that require just a few discrete components?

I looked online for some wired type modulators and I found some starting at around $40 (USD). If I can save a few bucks by building one, I would probably rather build it. Also, I'm kind of worried that they might just be overlaying the signal from the headphone jack onto the signal from the antenna. That's how my wireless transmitter works. It just overlays the signal. That's the main reason I want it to be wired, so I can simply cut the antenna out of the picture and get none choppy, none static, consistent audio. I also figure if I can build it for around 10 bucks, I would build a second one for my truck too. I also have a friend who wouldn't mind one either.

So, if anyone can assist me in build one, I would be very great full!

Thanks.

 

[Hero999]

Yeah OK, I new there was something different about the two.
What is the attenuator for? I'm mean, I know what it does, but why do I need it?

An FM receiver is very sensitive and can be overloaded by high powered signals so an attenuator is required to reduce the amplitude of the signal.

Does anyone have any diagrams / schematics? I checked the project section and they seem to all be wireless modulators.

Use a wireless transmitter, remove the antenna and connect it to the antenna jack via an attenuator and coaxial cable.

Are there any ICs out there that require just a few discrete components?

There are FM transmitter ICs available.

I looked online for some wired type modulators and I found some starting at around $40 (USD). If I can save a few bucks by building one, I would probably rather build it.

That sounds too expensive, you should be able to build a modulator for less than that.

You can even buy stereo FM transmitters for much less than $40, you could easily wire one to the antenna jack in the manner described above and in my previous post.

Also, I'm kind of worried that they might just be overlaying the signal from the headphone jack onto the signal from the antenna. That's how my wireless transmitter works. It just overlays the signal.
It's not that simple, I suggest reading the frequency modulation article on Wikipedia.

That's the main reason I want it to be wired, so I can simply cut the antenna out of the picture and get none choppy, none static, consistent audio. I also figure if I can build it for around 10 bucks, I would build a second one for my truck too. I also have a friend who wouldn't mind one either.

So, if anyone can assist me in build one, I would be very great full!

Does it have to be stereo?

A simple mono FM transmitter can be built fairly cheaply using a few transistors.

For stereo, you should use a specialist IC.