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The Wavemaker is to switch between two alternating power heads in the tank. It is possible to also add more power heads, but these will just be located on the same switch as the first two. Also could be used for one power head to turn on and off. Have to select a cycle time for the circuit which has two setting, one activated, one deactivated. Therefore it can be set such that a power head is on for one part of the cycle, then the other on is on for the remainder. Currently the cycle is set that one power head is on for 10 seconds, then the other for another 10 seconds, a cycle time of 20 seconds. It will have to be seen whether this is satisfactory when applied to a tank. The parts used for construction are as follows, all parts were purchases from Dick Smith Electronics;

1 x Multi timer module

Various different models are now available. One used has a cycle time that can be set between 0.1 seconds and 19.4 days, with an accuracy of 0.1 seconds. Has the option of using in single or cycle mode, the cycle mode is used.

1 x 2m extension cord

Used for the 240V AC power supply for the power heads. Ended up cheaper by getting the whole cord rather than purchasing the wire and the plug. 0.5m was cut off and the excess wire used for the 240V AC connections.

1 x SPDT high power relay

Single pole double throw relay. This is the relay that switches between the two power heads. The coil has to be able to be activated by a low DC voltage, 9V, and the contacts handle the 240V AC.

1 x SPST switch

Single pole single throw switch. To turn the Wavemaker on and off.

1 x Mounting case

Mount the whole unit inside, makes things nice and neat.

# x Assorted wire

Used for the various connections between components.

2 x Power points

Where the power heads will be plugged into. Can use a direct power point or one with a on/off switch. As an alternative could just use short extension cords with a socket on the end.

1 x 9V DC Power supply

To supply the operating power to the multi timer module.

1 x 3.5mm mono socket

For the power supply to plug into the mounting case.

The configuration of all the components is shown in the diagram below.

Wavemaker circuit diagram

Note that the relays are arranged such that if the power to the multi timer module is shut off, power head one remains in operation. (The relay labelled MTMRelay is located on the module circuit board, and comes as part of the kit) This could be possibly be used as a type of feeding setting, just have the power head that creates the least amount of turbulence in the tank as power head one. Draw back is that have to remember to turn it back on.

All that is needed is a little knowledge of soldering, assembly is really simple. Is a simple DIY project that is cheaper than commercially available Wavemakers, but it could be constructed for much less.

There may be a problem with the start up of the pumps with each cycle, possibly a little noise that could be cause damage to the pump impeller. What this will mean is that the impeller of the pump may fail around every two years, a bit of an estimate. The way around this is to use a soft start for the pumps. Don't know currently anything about this, but could be very easily added to the circuit.

Modification

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Shane found that when he attached the pumps to the relay output that when the relay tried to switch between the two pumps it would reset the relay and continually stay on pump 1. From someone more converse in electronics it was decided that this was due to the noise created from the high inductance pumps. To get around this involves simply wiring in a "snubber" into both of the outputs of the relay. A snubber is simply a resistor and capacitor in series across the outlet pins of the relay. This made the wavemaker now work perfectly, and now it works without a hitch. This should also lengthen the lifetime of the relay as well.

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