Hi, my orignial posts were here.
https://www.electro-tech-online.com/threads/rail-rail-opamp-output.9331/
https://www.electro-tech-online.com/threads/final-year-project-ideas.10008/
I wanted to control a relay with my PIC. I figured I'de use a MOSFET to connect the ground of the relay control when I wanted the relay on. Easy.
I went and got an N-Channel MOSFET and hooked it up so that:
Gate - Hooked to my pic
Drain - Relay Coil Control (12V)
Source - Hooked to ground
(if source and drain are reversed is the relay is ON all the time)
The idea is that when the my PIC sends 5V to the Gate, it connects the Source and Drain up so that my relay control is grounded and clicks on. Which it does...
However, when I turn the car on (plus sometimes randomly), the relay turns on too, but without my pic sending the 5V to the MOSFET!?
How can this happen? Its like the power is surging through the transistor? Possible? It seems like this transistor is overly sensitive, is there a better kind for me to use (a little more durable?) Or maybe a fix ?
(Aside note: When it does ghost-turn-on I click touch JUST the Gate pin with my finger and it turns off, then continues to function normally... Thats just bizzaro)
This actually kind of urgent and I really appreciate all the help everyone has given, this sort of thing would be impossible for me with out it. Thanks
https://www.electro-tech-online.com/threads/rail-rail-opamp-output.9331/
https://www.electro-tech-online.com/threads/final-year-project-ideas.10008/
I wanted to control a relay with my PIC. I figured I'de use a MOSFET to connect the ground of the relay control when I wanted the relay on. Easy.
I went and got an N-Channel MOSFET and hooked it up so that:
Gate - Hooked to my pic
Drain - Relay Coil Control (12V)
Source - Hooked to ground
(if source and drain are reversed is the relay is ON all the time)
The idea is that when the my PIC sends 5V to the Gate, it connects the Source and Drain up so that my relay control is grounded and clicks on. Which it does...
However, when I turn the car on (plus sometimes randomly), the relay turns on too, but without my pic sending the 5V to the MOSFET!?
How can this happen? Its like the power is surging through the transistor? Possible? It seems like this transistor is overly sensitive, is there a better kind for me to use (a little more durable?) Or maybe a fix ?
(Aside note: When it does ghost-turn-on I click touch JUST the Gate pin with my finger and it turns off, then continues to function normally... Thats just bizzaro)
This actually kind of urgent and I really appreciate all the help everyone has given, this sort of thing would be impossible for me with out it. Thanks