Battery charger - big is better, but even a small one able to kick out 6 to 10 amps should do. Electrodes of some sort. Small lengths of small chain. Mix well so all soda is dissolved. I take mine to a wire wheel on my grinder and give them just a real quick going over.
Place electrodes in bucket, around sides, so clean, rust free ends stick up above bucket.
Use wire, clamps, or some means to hold them in place, so that they cannot move freely, or fall into center of bucket. They must NOT EVER touch part to be cleaned, which will be suspended in center of bucket. I use small C clamps. Whatever you use, it shouldn't be copper, and will get a bit messy if it gets into your cleaning solution. Tie the electrodes together with wire, or cables.