For an energy harvesting application, I need to charge a capacitor using induced voltage due to the movements of a magnet inside a coil. The generated voltage is typically low frequency AC (4-5 Hz) with maximum 0.1 Vpp. This makes it extremely inefficient to use a traditional bridge rectifier, as the voltage is well below the active treshold of the diodes. What circuit could I use for the purpose?
I tried stepping up the voltage from the coils via a transformer (25:1) with no success. There also seems to be readily available ICs for the purpose, but they are unavailable at this time in my location. Also, it is worth noting that the capacitor should charge solely using the output of the coil, no external voltage supply is available.