Cleopatra said:
The man in Israel told me to test this but it didn't work. It's not that you cannot find spare parts and software, it's that none knows what he sells something that drives me crazy.
it seems similar to the US in this regard. There used to be magazines about this, like
Popular Electronics and
Radio Electronics. They recently had a reissue as PopTronics, but I don't know what happened to that.
To fix your high tec issues and represent yourself in court? 
(And don't tell me that you would do it better than the average lawyer...)
Fortunately, this hasn't come up. I probably couldn't do it better than the average lawyer, and I'd hire someone. I'm bright enough, however, to file the odd
amicus brief.
I suppose I have a basic understanding of law, and it's kind of frightening to me when people in civilized countries don't have a basic understanding of electricity and electronics. It seems to me that something important is being lost. This is quite true of the United States, less so in England, where up until fairly recently everyone needed to know how to wire a plug. So far I've thought the US was the worst, but this may not be so.
It frightens me because it turns electronic devices into purely consumer products and distances people from the fact that they're made from parts that people put together.
But I digress.
Anyway, as a public service, line output varies from .1 to 1 volt peak-to-peak. Newer devices use .1 volt. Headphone output varies between 0 and several volts. Speaker output can get to the order of 100 volts for really high-powered systems.
There are two easy ways of changing the voltage. One is with a transformer. These are kind of tricky, because some transformers are sold as impedence-matching transformers, and the input and output are given in ohms. To find the voltage difference, take the square root of the ratio.
If you just need to reduce the voltage of a signal, such as headphone to line, a voltage divider also works. These are simple. Take two resistors and wire them in series, that is, the end of one resistor is connected to the end of the other resistor, but the two remaining ends are free. Take the input signal (2 wires) and connect them to the free ends of the pair. Take the output across one resistor. The ratio of voltage reduction is the same as the ratio of the resistance of the one resistor to the sum of the resistances of the two resistors.
Or you can buy a potentiometer, also known as a volume control. This is just one big resistor with a wiper arm turned by the knob. It has three connectors. Put the input signal into the two outside connectors. Take the output signal from the center connector to one of the outside connectors. Which one you choose only affects which direction the potentiometer works, assuming a linear potentiometer. Twiddle the knob until the signal is right. Any potentiometer between 10K and 100K should work reasonably well.
There are also nonlinear (
i.e. volumetric) potentiometers, but these only affect how much the signal changes based on how much you turn it. If you're willing to twiddle until the signal is right, this doesn't matter much.
