techy

Hi guys,

I have been hunting high and low in the internet trying to find a DIY on this soft-start switch but, it seems like it is not very common. I want to use this to control the start and end of powering a Powerhead in my fish tank. I've successfully built a wave pulse control switch. This switch is controlling 2 or 4 powerheads in the tank based on the onboard timer. The problem is, each time it start the powerhead, the full inrush of the Ac current will cause the powerheads to rattle. I learned from the internet that, by doing so, the life span of the powerhead will shortened dramatically from about 10 years to 2 - 3 years. There is one commercial unit which have the soft-start feature but the unit cost almost USD170.00 (wave mater pro).

If someone can let me know where to find one of this project in the internet or even better, such a switch that is available in the market (like a light dimmer), that will be great. Thanks in advance for the help.

cheers, 8)

Chippie

One method of soft starting AC motors is to use a tapped transformer....

All you need is an auto transformer with a tapped primary...capable of taking the flc of the motor.......the switching of the tappings can be carried out using a timer with suitably rated contacts......


HTH Chip

bogdanfirst

well, i got something like it first connects the load trough a 40R series resistor and then it shorts the resistor connecting the device directly.....
interested?

techy

Hi Bogdanfirst,

Am interested in your idea as it sounds simpler. Could you pls let me know. FYI. I am staying in Singapore and the local AC is rated 220 - 240 v. Thanks in advance for your help.

Chippie,
Thanks for letting me know. I'll try Bogdanfirst's proposal first since it sounds simpler. Thanks.

cheers,

bogdanfirst

ok, here is the schematic
for 240V/50Hz C1=470n, C2 -you dont put it.
thats it.
o, and be carefull!!!!!!!!

Attached Images

connect.jpg (124.7 KB, 310 views)

techy

Thanks alot for your help, Bogdanfirst.

cheers,