Hello there. I have a question about a simple circuit I am constructing.
A principal part of this circuit involves two N-channel MOSFETs configured to act as high-amp switches to turn on and off a pair of LED strips. These MOSFETs are designed to control each LED strip independently and therefore should be logically isolated.
For a reason currently unclear to me when one MOSFET is turned on and the other off, the MOSFET which is supposed to be off has current flowing through the drain.
Attached is a schematic of my most recent and simplified experiment. As you can see from the graphic, MOSFET (B) appears to be configured so that its load is never driven, yet when the push button is closed and MOSFET (A) is turned on this seems to cause "LED Strip B" to also turn on.
I tested the LED strips to make sure there was no short and each one works fine when powered directly without the MOSFETs. I also tested each transistor independently with its corresponding LED strip and they work as expected. Its only when both MOSFETs are involved that this problem manifests itself.
After performing the test shown in the graphic, I removed "LED Strip B" and put a multimeter probe on the drain of MOSFET (B). When the switch is open the voltage reads a little over 6 Volts. This is curious to me because I figured it would be high impedance (floating), a capacitance effect maybe?
When I close the switch the voltage is a solid 0 indicating that the transistor is turned on.
Any ideas what could be wrong here and how I can independently control each LED strip?
A principal part of this circuit involves two N-channel MOSFETs configured to act as high-amp switches to turn on and off a pair of LED strips. These MOSFETs are designed to control each LED strip independently and therefore should be logically isolated.
For a reason currently unclear to me when one MOSFET is turned on and the other off, the MOSFET which is supposed to be off has current flowing through the drain.
Attached is a schematic of my most recent and simplified experiment. As you can see from the graphic, MOSFET (B) appears to be configured so that its load is never driven, yet when the push button is closed and MOSFET (A) is turned on this seems to cause "LED Strip B" to also turn on.
I tested the LED strips to make sure there was no short and each one works fine when powered directly without the MOSFETs. I also tested each transistor independently with its corresponding LED strip and they work as expected. Its only when both MOSFETs are involved that this problem manifests itself.
After performing the test shown in the graphic, I removed "LED Strip B" and put a multimeter probe on the drain of MOSFET (B). When the switch is open the voltage reads a little over 6 Volts. This is curious to me because I figured it would be high impedance (floating), a capacitance effect maybe?
When I close the switch the voltage is a solid 0 indicating that the transistor is turned on.
Any ideas what could be wrong here and how I can independently control each LED strip?