Outer Limits 4x4 Board

Hi there,

I need to relocate my UHF speaker and I am in the process of installing a car kit.

Is there any way that I can use one speaker to run both the phone and the car kit without a switch or anything like that?

Thanks
Paul

You would need to wire in diodes to prevent back voltage from one device going to the other. You would also need to determine which of the 2 speaker wires is + and -. Then you will need to determine if the impedance of the speaker suites both sources.

Then you would need to decide if you can get by with listening to 2 voices at the same time.

Don't you have space under a seat for a second speaker. The UHF CB should have a powerful enough speaker output to drive a speaker under your seat and still be able to hear it clearly.

v6hilux wrote:You would need to wire in diodes to prevent back voltage from one device going to the other. You would also need to determine which of the 2 speaker wires is + and -. Then you will need to determine if the impedance of the speaker suites both sources.

Then you would need to decide if you can get by with listening to 2 voices at the same time.

Don't you have space under a seat for a second speaker. The UHF CB should have a powerful enough speaker output to drive a speaker under your seat and still be able to hear it clearly.

Ignore the above post. Simply wrong.

What you need is a small seperate amplifier to run the speaker, and three resistors forming an audio mixer attatching the speaker outputs of the phone and the UHF to the input of the amplifier.

dmika is much much closer to the money, diodes prevent current flow in one direction as sound is AC it will stop the top (or bottom) half of the wave and not the other and generally be up the shit.

there are ways as dmika has mentioned using resistors to pull the output down then mix at line level and amplify again but all in all i would simply run the two speakers. much easier.

Thanks,

Thought it was worth a shot.

Paul

i have seen speakers with dual voice coils that may be worth a try if they come that small

I bought a mp3/cd player a while back and it had an aux in socket. I thought it would be something I'd never use as I dont have, nor intend on buying a little mp3 player/ipod to plug into it. Well I only have a handheld uhf and its always done the job for me in the bush but on the highway with the soft top and tyres it gets very noisy and you simply can't hear shit. So I had a thought about trying to plug the uhf into the aux jack on the head unit with the correct cable. It works so well, just turn the volume up on the headunit as you please and its more than loud enough to overcome tyre/wind/old 40 noise.

The handhelds usually have a headphone jack on them for attatching a handsfree mike/headphone (I think its called VOB?), this is where you plug the aux cable in. Not sure if vehicle mounted uhfs have a similar plug but it would be another option if you have an aux plug on your headunit. That way you leave the handsfree phone setup as it is and just switch your headunit to aux when you want to use the uhf. Only problem is you cant listen to music and the UHF at the same time. I'm a bloke and therefore I cannot multitask so its perfect for me.

bigcam wrote:diodes prevent current flow in one direction as sound is AC it will stop the top (or bottom) half of the wave and not the other and generally be up the shit.

I don't know about that either, Yes the sound into the output amp is AC, however the sound out of the amp is DC, I assume!

I have watched speakers operate and they pump the air to create a sound wave. I have never seen them pull the other way, unless they are wired incorrectly, as in polarity!

Am willing to learn more if this is not correct!

RAY185 wrote:So I had a thought about trying to plug the uhf into the aux jack on the head unit with the correct cable. It works so well, just turn the volume up on the headunit as you please and its more than loud enough to overcome tyre/wind/old 40 noise.

Awesome idea!

v6hilux wrote:Am willing to learn more if this is not correct!

Well the first lesson to learn is ignore everything you have typed in this thread.

r0ck_m0nkey wrote:

v6hilux wrote:Am willing to learn more if this is not correct!

Well the first lesson to learn is ignore everything you have typed in this thread.

Agreed. If you don't REALLY know, don't guess, if it has the potential to cost people money or time. Common courtesy, really....

There is possibly a way to do this using a relay/s. Older vehicles had radio & cassette units that were completely seperate, but used the same speakers. These were wired up using multi pin relays that had the speakers wired thru them. I assume you are installing a mobile phone kit therefore it probably has a trigger wire for radio muting. This wire could be used to trigger a relay to swap the sound being received from each unit. An older auto elec may have these relays & may even remember how to wire them up.

It would only require a double pole change-over (DPCO or DPDT) relay to do this - should be available from somewhere like Jaycar. Speaker wired to common, radio source to NC contact, phone source to NO contact. Energise the relay when the phone mute signal goes active.

OK, one relay per speaker - how many speakers do you want to hear your phone through?

Just Wire both sources to the speaker via audio Isolating transformers ie 8ohm to 8ohm Transformers to give them DC Isolation from each other and go for it........its done all the time.
Most don't even worry about the Transformers.....But as a precaution I would use them

Harb wrote:Just Wire both sources to the speaker via audio Isolating transformers ie 8ohm to 8ohm Transformers to give them DC Isolation from each other and go for it........its done all the time.
Most don't even worry about the Transformers.....But as a precaution I would use them

Thanks for that, would jaycar know what im on about if I went in there talking about this?

Paul