Schatten VVM Pro. Violin/Viola Pickup - SH-VVM-Pro
The VVM-2 Series offers the solution to this problem. A small lightweight sensor simply adheres to the bridge with a little bit of putty.
These pickups were designed for quick and easy installation and removal and will provide you with a means for amplifying your instrument when you need it. Plus it has a handy thumbwheel volume control built right into the jack assembly.
When you don't need a pickup, the VVM-2 can simply be stored away. They come complete and ready to go with no wiring, no soldering, no fuss. Fits violins and violas.