For low frequencies (<200 Hz or so) any arduino will do. In theirs work freq. 75-125 Hz, and since 3-rd harmonics of the lowest 75 doesn't interfere with the highest 125, you even don't need a pure sine. Rectangular pulses would be o'k to drive electromagnets.Perfectionist, like me, would make clean sine wave oscillators, combining arduino UNO + LTC1665 (8 channel DAC) to create a 5-8 channels generator. Than drivers, any audio amplifier 'd be o'k.
Thank you for the suggestions. Now I have some idea on the tools needed, but how do I go and do it? I saw that I can use PWM, but then what? Do I use an opamp, do i switch the pinmode between INPUT and OUTPUT, do I use DAC? I have googled a couple of approaches and don't know which to chose. I want to have 5 channels with different frequencies between 50 and 200Hz.