Can someone help me with a circuit design for a variable speed fan controller that will change fan speed using a photocell. It would need to be able to have a variable speed control for both day and night time operation.

 

DC or AC fan motor? How many volts, how many amps or watts?

 

Sorry about that. 115VAC, I think a max of 2 amps would be more than adequate. These are not very large motors, maybe 1/6 - 1/4 hp max.

 

Hello,

How is the relation between day/night and the speed of the fans ?
Must it be a light dependend speed regulation or high / low speed ?

Greetings,
Bertus

 

The fans would typically run at a lower speed at night. I was asked by a friend about this device. My understanding is that he does not want to use a mechanical timer, but a photocell to actuate mode. He also asked that the speed of the motor must be adjustable in both the day and night modes of operation.

 

I was wondering if anyone had a answer to this question. Basically I want to power 2 dimmers/speed controllers with a photo cell, one dimmer on during light and one dimmer on during dark. It would control a 120v 3a attic vent fan, I want it to run at 75-100% speed during the day and 25% speed at night.

 

Its just a Hi-Low setup..