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Line Out - Line in Volume reduction

Community Veteran
Posts: 17,025
Thanks: 1,218
Fixes: 13
Registered: 06-11-2007

Line Out - Line in Volume reduction

Got me a new shortwave portable receiver, which I want to link up to my laptop, to receive PSK31,RTTY,SSTV,Etc.
Normally this is done by a double ended jack lead, from the REC or Line Out, on the back of the receiver, to the MIC on the laptop. However, this portable receiver does not have a Line Out or REC socket, only the earphone socket. and the level is very high and likely to damage the soundcard.
So.... I need to be able to reduce the output level from the earphone socket to a similar/comparable "Line out" level. 
Calling on all you techy`s to suggest how I can do this for next to no money...and of course, very simple.....  I was thinking of a resistor in the line, but don`t know what value it would need to be....
It would be nice if I could also use the speaker  to listen to the signals, at the same time, but plugging in a jack plug cuts out the speaker, as for using with phones. I suppose I could wire up an external speaker and use that, with a jack lead into a double socket to single plug adapter.
If you need to send me a circuit diagram, with parts list. pleas PM me for my email address....
Thanks guys.  Wink
7 REPLIES
Community Veteran
Posts: 6,341
Thanks: 481
Fixes: 44
Registered: 30-07-2007

Re: Line Out - Line in Volume reduction

Community Veteran
Posts: 17,025
Thanks: 1,218
Fixes: 13
Registered: 06-11-2007

Re: Line Out - Line in Volume reduction

That looks like it might be useful..... I could measure the resistances Low & High..... then turn the volume down to zero, and adjust up until the "overflow" appears,.... read the resistance and then put a slightly lower in-line fixed resistor to ensure I did not overload when plugging in the line.
Thanks MisterW  Wink
Update....
Have seen one on ebay  (Exactly the same pic) for £3.25 inc post.... so ordered it....
Many thanks
Community Veteran
Posts: 6,341
Thanks: 481
Fixes: 44
Registered: 30-07-2007

Re: Line Out - Line in Volume reduction

I have something similar which I use when on holiday in Portugal. We like to listen to the radio in bed and of course a portable radio is no use for UK radio. The apartment has a satelite box on which one can of course receive UK radio. So I have a video sender connected to it but instead of a TV in the bedroom I just have a portable speaker system. I just use the audio output on the receiver through a phono->3.5mm jack adaptor and then through the inline volume control to the speaker system. Works a treat!. Smiley
   
MJN
Aspiring Pro
Posts: 1,093
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Registered: 26-08-2010

Re: Line Out - Line in Volume reduction

Does your laptop not have a LINE IN socket (usually coloured light blue)? The levels will almost certainly be too high, as you've found, for the MIC input (pink). The MIC input will be expecting a very low signal level and thus will likely have a built-in amplifier causing your signal to saturate and input and cause distortion.
To control the input level to the LINE IN just adjust the volume control on the receiver.
Community Veteran
Posts: 17,025
Thanks: 1,218
Fixes: 13
Registered: 06-11-2007

Re: Line Out - Line in Volume reduction

No, the laptop(s) do not have a line in socket... only the MIC.. socket... The lead that MisterW suggested and my following posting, should solve the problem.
Thanks for the input...  Wink
MJN
Aspiring Pro
Posts: 1,093
Thanks: 39
Fixes: 2
Registered: 26-08-2010

Re: Line Out - Line in Volume reduction

Gotcha. I assume therefore that there's no volume control on the receiver?
Community Veteran
Posts: 17,025
Thanks: 1,218
Fixes: 13
Registered: 06-11-2007

Re: Line Out - Line in Volume reduction

Yes, there is a volume control on the receiver, but I need that to be high, as my hearing is not too brill !... (two hearing aids)..
loss of hearing caused by listening to radio "mush" in between signals for 10 years  ! ! ..