Norm's Web Page
Current Maker
Here is a simple device you can use to vary the currents in your tank. It is not really a wave maker since the cycle intervals are 30 minutes. I built this because I wanted my tank to have variable currents but not cycle my powerheads on and off hundreds of times a day. I also wanted to spend $10 on a timer, not $60.
A lamp timer is used to trigger a relay on and off every 30 minutes. I bought the kind of timer that has buttons you can push up and down instead of the kind that have keys you have to insert. I have every other button on. This then energizes and de-energizes the relay every 30 minutes. The relay is wired so one receptacle is normally on and one normally off. When the relay is energized the one that was on goes off and the receptacle that was off is then energized. You could easily use two duplex receptacles and have one wired normally on and one wired normally off. I got my relay at Radio Shack (275-217) and I used the relay socket (275-220) to make the wiring easier. Total cost: about $30.
Use this schematic at your own risk. The author takes no responsibility for any damages or injury caused as a result of using this information.