Universal Measurement Amplifier/Attenuator (Gerber)
If you build or repair audio equipment yourself, you don’t always need an os- cilloscope. Any direct current or volt- age can be measured with a multime- ter. You can do a lot more if you happen to have a better model that can also measure (small) AC voltages.
For more advanced measurements such as the frequency response or the distortion it is very handy to use the soundcard in a computer combined with some software. A laptop or note- book can also function without an AC outlet, which means you’ll avoid earth loops and hum during measurements. However, a laptop often has just an oversensitive (microphone) input, so that you need to make a range of volt- age dividers for your measurements. This measurement amplifier has been designed especially for these situa- tions. It has an adjustable input at- tenuation and an input impedance of 1 MΩ, so that standard scope probes with built-in attenuators can be used for even larger AC voltages.
From: Elektor 7/8-2012: look for the article on this page
Note: a gerber file is not a printed circuit board or PCB. Gerber files must be sent to a PCB manufacturer (recommendation: www.elektorpcbservice.com) who can make the PCB with it.