Re: Sound card question
On 10/02/2015 11:27 AM, Danny wrote:
I believe that the output of the headphone jack is not impedance matched--I expect it's just
a voltage source. Wat's more, unless you are plugging the same low-impedance devices into
both Y outputs, _and_ the source is impedance matched, you would not split the power
equally. I don't know what you want to do with the second output, but it's more
than likely a relatively high impedance, so it would not load the circuit at all.
I could be wrong, but it seems logical to me.
--doug
O.k ... let me explain why I asked the question for the sake of satisfying any
curiosity:
I have EchoLink (Ham Radio VOIP) connected to Jessie like this:
VHF Transceiver (with two interface cables going to the MIC and LINE-OUT jacks
on the back of an internal sound card. Incoming audio (radio frequency)
goes through the antenna ... through the transciever ... to the sound
card (via the MIC interface cable) ... it gets processed by the sound card and
stuff happens on VOIP ... Because the VHF transceiver is effectively turned into a
repeater NO transmit or recieve audio can be heard on the transciever itself
(as it should be).
In order to hear comms coming in or out of the transciever (via an antenna) one
has to connect to the transciever with ANOTHER transciever in order to hear
people talk (if you are tuned to the same frequency off course)
Now ... my second transciever is fitted inside my car ... in order for me to
hear all comms on the frequency I need to go to my car and turn that transciever
on every now and then which becomes a pain in the donkey ... ;) ...
In order for me NOT to make a trip to the car every 10 minutes I though of
splitting the LINE-OUT and add a normal set of desktop speakers.
So ... I was just wondering if I will have any losses (in whatever form) when I
"split" the signal ... keep in mind that the audio signals processed by the sound
card should be strong and reliable ...
Thank You
Danny
You didn't mention that you want to add _speakers_. You might need a small amplifier
after the Y-adapter, since the speakers will be low impedance--4- or 8 ohms.
Visit ramseykits.com and find some small audio amplifiers in kit or assembled
form. They are probably overkill for your purpose, but cheap enough. A 14W stereo
kit, CK154, will run on 12 to 16 VDC at 1A. $26 for a kit, or $34 assembled. You
provide an enclosure and a wall-wart to drive it. (The "14W" rating is for 7W per
channel, and I would expect that it's a peak rating, since 16V at 1A is 16 Watts
_input_ power! I would guess that rms power is more like 2 or 3 Watts per channel.)
I just noticed a smaller one in ramsey: CK122 $20 for the kit, $26 assembled.
0.5W per channel into 4 ohms. Runs on 6VDC. Probably enough for your purposes.
There are other small amplifier sources--check on Google.
--doug
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