1. Home
  2. Electronics Design
  3. Headphone to RCA

Headphone to RCA

I'm looking to interface the headphone jack on my laptop with an RCA jack on my TV. I already have a cable that goes from 1/8th inch stereo to stereo RCA. The problem is, the volume is terribly low and loud noises (such as explosions during a movie) cause the output to saturate and the volume drops even more. So I figured I could build a simple op-amp circuit. I've been looking everywhere for the electrical characteristics of the headphone jack and the RCA jack but I can't find anything! Apple's website lists the characteristics of their headphone jack as having a peak output of 4.5Vp-p with a 10 ohm source impedance. Of course, I have a Compaq laptop, but I figured mine is probably about the same, at least with respect to the peak output voltage (which is all that really matters with an op-amp since 10 ohms is nothing). Also mentioned that headphones have an impedance of 32 ohms so I thought I might make the input impendance of my little amp 32 ohms. But I can't find anything about the RCA jack. In particular, it'd be nice to know what the max voltage is that it expects. I wouldn't want my amp to drive it too high. Any information or other insight would be great!

Reply to
trogadoror
Loading thread data ...

I'm a little surprised by the things you state in your post. I would expect that the headphone jack could drive the RCA on your TV at an appropriate level. Have you tried experimenting with the level (volume control) on your headphone jack?

If you do end up making an amp, you probably don't want to make the input impedance 32 Ohms. That is a tough load for your computer to drive, and there isn't much benefit to forcing it to do so. Most likely you will get better sound quality if you use a much higher input impedance, like 10 K or even more.

Hopefully some of your other questions will be answered by other posters.

--Mac

Reply to
Mac

I read in sci.electronics.design that trogadoror wrote (in ) about 'Headphone to RCA', on Sat, 18 Dec 2004:

No, you don't need to do that. The headphone output will drive a high impedance load quite OK.

It wants 200 to 500 mV, that's all, if it's a line-level input and not a mic input. So it should work OK, or maybe you'd need an attenuator rather than an amplifier. Does the laptop socket work with headphones? If it does, maybe the volume control on the laptop is set very low. Try increasing its setting. Make sure the output isn't muted, too. You might be listening to the bit that leaks past the muting device.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
Reply to
John Woodgate

Just being pedantic here but small jacks are actually metric sizes. I expect you mean 3.5mm.

The output of what ? saturates. The TV ? Wouldn't be surpised. Movie sound tracks have more dynamic range than normal TV programmes.

You don't need one.

In which case it has plenty of volts available already to drive any input it's likely to be connected to.

No. A headphone output will drive a higher impedance load ( such as the TV ) with less distortion anyway. Those internal headphone amps are pretty crap. It's a common misconception that audio loads have to be 'matched'.

You don't need an amplifer.

The other answers you've received pretty much wrap it up.

Graham

Reply to
Pooh Bear

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.