I am making a small incubator using a 12V 20W halogen lamp as the element, controlled by a Picaxe 08M.
I have a logic level N channel FET type STP36NF06L 60V 30A, which is a bit of overkill, but a generalised solution that has a little headroom to spare for slightly larger applications.
I am not FET aware but have put a 4k7 ohm resistor in the gate lead and observed that it appears to work just fine. I chose the FET after reading the thread that discussed FET heating when not fully conducting. This device seems simplicity itself, but feel that being voltage driven, that the resistor could easily be 47k ohm or more, but what are the merits of the existing or much greater value resistor?
My question, is there a more appropriate value that I could or should be using when keying/switching the gate via the resistor from an 08M output port?
FET datasheet here Rapid Electronics part no 47-0552. The FET is on the low side of the lamp, which is supplied directly from 12V nominal (13.8V) and the Picaxe 08M powered by a 7805 derived 5V supply. Temperature sensing using readtemp with a DS18B20 chip.
I have a logic level N channel FET type STP36NF06L 60V 30A, which is a bit of overkill, but a generalised solution that has a little headroom to spare for slightly larger applications.
I am not FET aware but have put a 4k7 ohm resistor in the gate lead and observed that it appears to work just fine. I chose the FET after reading the thread that discussed FET heating when not fully conducting. This device seems simplicity itself, but feel that being voltage driven, that the resistor could easily be 47k ohm or more, but what are the merits of the existing or much greater value resistor?
My question, is there a more appropriate value that I could or should be using when keying/switching the gate via the resistor from an 08M output port?
FET datasheet here Rapid Electronics part no 47-0552. The FET is on the low side of the lamp, which is supplied directly from 12V nominal (13.8V) and the Picaxe 08M powered by a 7805 derived 5V supply. Temperature sensing using readtemp with a DS18B20 chip.
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