My girlfriend and I were looking at a largish saltwater aquarium today and thinking about setting one up. This tank (2 meters long) had a 240V AC power head (water pump) at either end, at around ten second intervals one power head would turn off and the other would go on full power. This cycling of the power heads creates a surge current similar to the effect of the swell washing over a coral reef. The fish and corals do better with this sort of set up. They had a $$$$$pricey german made controller to run the power heads.
To decrease the wear and tear on the power heads I was thinking it would be good to have a soft start using PWM. I've seen this on AC 240V power tools to reduce start up kick ( large angle grinders for instance) so I presume it must to be technically possible.
Im thinking of using a 40X1 picaxe to run the tank anyway so its no big deal to have PWM control of the pumps as well. The 40X1 could control the lighting, temperature, water level and provide alarms of pump, heater failures, water level drops through leaks etc.
 
Edited by - BrendanP on 19/08/2007 10:32:28
To decrease the wear and tear on the power heads I was thinking it would be good to have a soft start using PWM. I've seen this on AC 240V power tools to reduce start up kick ( large angle grinders for instance) so I presume it must to be technically possible.
Im thinking of using a 40X1 picaxe to run the tank anyway so its no big deal to have PWM control of the pumps as well. The 40X1 could control the lighting, temperature, water level and provide alarms of pump, heater failures, water level drops through leaks etc.
 
Edited by - BrendanP on 19/08/2007 10:32:28