klotzkm Posted July 11, 2016 Share Posted July 11, 2016 I am attempting to use a CMB24D to control both RGB LED lights, and a 12V 3A sump pump... this in order to build a "Mini-Bellagio Fountain" display. On initial tests, I continued to blowup the MOSFETs, despite that the pumps were only drawing 3A...and after I installed heatsinks. I figured it may be due to reverse current from the motors, so I added an inexpensive rectifier diode across the power and drain in order to dump any feedback current/voltage away from the MOSFET. So far, this addition seems to have solved all my problems, including reducing much of the heat that the MOSFET was attempting to dissipate. Kurt Largo, Florida Link to comment Share on other sites More sharing options...
plasmadrive Posted July 12, 2016 Share Posted July 12, 2016 Those motors can draw a lot of current on startup and put one heck of a reverse voltage spike out when you turn them off or if they become an over hauling load. From what you posted here I assume the reverse spikes were what was killing them. Let us know how it works long term for you.. Link to comment Share on other sites More sharing options...
k6ccc Posted July 12, 2016 Share Posted July 12, 2016 Have the CMB24D control a relay and have that power the pump. BTW, you still should put a diode across the relay coil to kill any reverse spike when the power is removed from the relay coil. Link to comment Share on other sites More sharing options...
k6ccc Posted July 12, 2016 Share Posted July 12, 2016 If you want to understand what is going on, you can take a look at this link: https://en.wikipedia.org/wiki/Flyback_diode Also, if you need assistance with a schematic for adding a relay, let me know and I'll draw one for you. 1 Link to comment Share on other sites More sharing options...
Recommended Posts