I am making a torch without batteries ie. It has a neodymium magnet in a 1" PVC pipe with 1000 turns of enameled magnet wire and generates 4.4V AC easily, then I'll put the rectifier and then connect the rectifier to a 5.5V 1F super capacitor which has two 5mm piranha LEDs connected to it via a switch. So now I can't decide what bridge rectifier to use ? I have 1.5 A rectifiers, so would they work ? If not then what should I use ?
How to decided which bridge rectifier to use
amperagebridgerectifier
Related Solutions
In most cases, paralleling diodes is not a good idea. Their forward voltage drops Vf can be different, if they are not from the same batch. As a result one diode with the lowest Vf in the bank will conduct more current than the rest and more than it's rated for. That diode will get burned. Then the next one will get overcurrent in the same fashion. Untill all of the parallel diodes in the bank are burned. I'm afraid that the quote in the O.P. is describing this [wrong] approach.
But a bridge rectifier could lend itself to a possible workaround. Suppose, you've got 4x bridge rectifier ICs. You must assume that they are not from the same batch. But each of the diodes inside the bridge is from the same batch, because they are on the same die.
Notice that there are parallel diode connections within the bridges, but not between the bridges. No more than 2x bridges can be paralleled this way.
Proceed with caution. Best of all, just get a single bridge with sufficient current rating.
The type of rectifier shown in your picture is intended for bolting directly to a heat sink via the hole in the center. It is for large currents.
For smaller currents, there are bridge rectifiers that have lead terminals for through-hole soldering. Or else you can use four diodes like 1N4001's.
Bridge rectifiers are not usually socketed, so that may be why "bridge rectifier socket" doesn't turn up much. Including yours. The rectifier you have has connector terminals exactly for the reason that it ends up being bolted to a chassis, away from both the transformer and the circuit board that it supplies. In these situations it has to be disconnected so the circuit board can be removed without removing the rectifier from the case.
Best Answer
Any (rated for the voltage and current expected) should work, but I suspect that high voltages may be developed from such a strong magnet in a large coil if shaken fast enough (perhaps hundreds of volts if dropped.) Of course, load will reduce this greatly. Test it using your proposed maximum shaking motion, and measure the voltage and current into a real rectifier / cap / load. May have to use an oscilloscope to see V/I accurately; a DMM will just show you averages, not peak values.
Also note, the more load you place on the coil, the slower the magnet will want to move through it, which could hamper the shaking motion. You may find that 10,000 turns will produce a higher voltage and work better. Experiment with it. Once you know what's actually produced by the coil, then you can look at faster and/or lower-loss rectifiers to achieve a bit more efficiency.
But say, if the coil is found to produce a peak value of 100v and the rectifier is only rated for 50v, then it may avalanche (conduct the wrong direction) and permanently fail. You want to get rectifiers that are rated for at least twice the expected peak voltage. So in this case, you'd want to get them rated for 200v minimum.