Control DC (Fan) 12V 5A Circuit request

[sruger]

I have a roof vent fan I would like to control (have different variable settings) and would like to request assistance in advance. I have a 12V 5A power supply that can peak at 7A, but turns off due to overheating after 15 minutes at unregulated full speed. I would like to have a low, medium and high setting (and reverse fan direction if possible), and keep the current at a maximum of 5A on High. I only work with PICS and do not trust my electrical experience enough to keep from burning the RV down. I would like to use common parts if possible.

Thanks for your input,

David

 

[Boncuk]

Hi sruger,

working with any kind of MCU is a good start for your project.

Make it put out two different PWM signals, one for forward, one for reverse and connect a power H-bridge (L298, Multiwatt15 package) to the outputs.

Limit PWM (e.g. 80%) not to overstress the power supply.

If your fan is a radial type remember that reversing rotation just results in 30% of the forward air flow at max. rpm.

Boncuk

 

[rjvh]

How big is your fan motor ????

even with PWM you can push the supply into limits over time, the fact that it max can give 7 amp doesn't mean that you can control a fan that consumes 10 amp on a duty cycle of 50%

I would first look how much your fan motor is consuming and than look to your power supply side

for controlling PWM is defenetly the way to go in my opinion

Robert-Jan

 

[sruger]

Thanks for the suggestions, I will look into this more.

Thanks