Hi,
I am building the attached circuit to turn on a motor for 60 seconds, then turn off for between 2 minutes and 5 minutes, and then repeat. A PIC12F675 is used and the variable delay is achieved by adjusting the 10K pot and the A/D conversion of the PIC.
I am testing the attached circuit on my bench using a 12VDC electric drill as the motor. The drill is drawing ~4amps. When the design is finalized, I would like the circuit to power a motor up to 10amps.
The PIC and its software, along with components associated with the PIC work fine. I have build a few circuits using a PIC to drive a relay and haven't had any problem.
This is my first attempt using a MOSFET. I am using a IRF540 and have attached an aluminum heatsink (removed from my old stereo).
I tried turning on the MOSFET using the 5V from the PIC but didn't have any luck. I used an OPTO I had laying around and got the motor to turn on, but after a short time (20 seconds) the MOSFET/heat sink got very hot. Too hot to touch. I ran the PIC program for one or two cycles and decided to shut it down before something melted.
I need some advice/help on using this MOSFET to turn on the motor but configuring it in such a fashion as not to over heat it. Any suggestions would be appreciated on how to keep avoid this over heating down or other circuit suggestions.
Thank you.
JG
I am building the attached circuit to turn on a motor for 60 seconds, then turn off for between 2 minutes and 5 minutes, and then repeat. A PIC12F675 is used and the variable delay is achieved by adjusting the 10K pot and the A/D conversion of the PIC.
I am testing the attached circuit on my bench using a 12VDC electric drill as the motor. The drill is drawing ~4amps. When the design is finalized, I would like the circuit to power a motor up to 10amps.
The PIC and its software, along with components associated with the PIC work fine. I have build a few circuits using a PIC to drive a relay and haven't had any problem.
This is my first attempt using a MOSFET. I am using a IRF540 and have attached an aluminum heatsink (removed from my old stereo).
I tried turning on the MOSFET using the 5V from the PIC but didn't have any luck. I used an OPTO I had laying around and got the motor to turn on, but after a short time (20 seconds) the MOSFET/heat sink got very hot. Too hot to touch. I ran the PIC program for one or two cycles and decided to shut it down before something melted.
I need some advice/help on using this MOSFET to turn on the motor but configuring it in such a fashion as not to over heat it. Any suggestions would be appreciated on how to keep avoid this over heating down or other circuit suggestions.
Thank you.
JG
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