Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Tnx & 73, Tom

"Tom, N3IJ" wrote in message
...
Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Tnx & 73, Tom

Typically it needs DECREASED not increased. There are circuits on the
internet for attenuating the output sound level from the computer to be
acceptable to the radio for digital modes. One could potentially use the
volume control on the computer but since the level is relatively high, it's
hard to get the fine control without an attenuator between the computer and
radio.

Dee, N8UZE

On Sun, 21 Dec 2008 11:45:51 -0800, Tom, N3IJ wrote:

Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these levels
are. I want to drive a line-level transceiver input for digital hamming.

Any suggestions would be appreciated.

You have an impedance mis-match. Use a radioshack xformer with the 8ohm
side on the headphones jack and the 5k output to the line level. You will
need a pad or simply a pot after that.

On Dec 21, 2:57*pm, "Dee Flint" wrote:
"Tom, N3IJ" wrote in message

...

Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Tnx & 73, Tom

Typically it needs DECREASED not increased. *There are circuits on the
internet for attenuating the output sound level from the computer to be
acceptable to the radio for digital modes. *One could potentially use the
volume control on the computer but since the level is relatively high, it's
hard to get the fine control without an attenuator between the computer and
radio.

Dee, N8UZE

I saw something with an 8 ohm resistor from the output of the
soundboard to ground and a 10k resistor from there to the input of a
tape recorder.

Jimmie

Tom,

I'm not using a laptop, but my desktop has sufficient audio output to drive
line-in levels on the rear of Icom transceivers. If your laptop does not
produce high enough levels (see other responses about impedance matching),
it might be cheaper and "cleaner" to buy a little USB audio sound card
(Turtle Beach has one for $30, about the size of a thumb drive) and grab
audio output from that.
--
-larry
K8UT
"Tom, N3IJ" wrote in message
...
Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Tnx & 73, Tom

"No Spam" wrote in message
...
On Sun, 21 Dec 2008 11:45:51 -0800, Tom, N3IJ wrote:

Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these levels
are. I want to drive a line-level transceiver input for digital hamming.

Any suggestions would be appreciated.

You have an impedance mis-match. Use a radioshack xformer with the 8ohm
side on the headphones jack and the 5k output to the line level. You will
need a pad or simply a pot after that.

An impedance mismatch in this case only equates to a possible power loss.
The transformer (I think RS only offers a 600:600 ohm line transformer)
is good because it offers some isolation between the equipment.

Is your laptop audio stereo or mono? You'll have to take that into
consideration,
since you don't want to short on of the channels using a mono plug.
If stereo, you will need to work up some sort of passive mixer
(resistors would do it) to combine the two channels.

Pete

On Dec 21, 2:45*pm, "Tom, N3IJ" wrote:
Can anyone suggest a source of a circuit or kit for a mono amp to
increase my laptop's headphone output level to line level?

As a starting point, it would be helpful just to learn what these
levels are. I want to drive a line-level transceiver input for digital
hamming.

Any suggestions would be appreciated.

Line Level for consumer audio is -10dBV or 0.316V RMS or just below a
volt peak-to-peak. Solid state audio equipment typically has an input
impedance in the kohm range.

Usually a headphone jack has more than enough output. Some sound cards
or laptops are "energy smart" and turn off the output if they don't
see a low-impedance load plugged in. Other times they have their own
volume controls that can be overridden by Windows and sound card
settings. Other times common-mode noise can dominate (drowning out the
signal) giving a very real advantage to using an isolation
transformer. There are many many articles on the web about using
isolation transformers to hook your computer to your radio.

Tim N3QE