ok so after a couple of years and basic circuits with the picaxe the time has come for me to brush aside transistors and look at playing with mosfets.
so firstly the mosfet i was looking over is a dual channel n and p soic8 package,
datasheet: View attachment FDS8958A.pdf
now the project is to replace my old and finally dead winch controller for an rc trailtruck/rock crawler which will also allow me to include an 08m2 soic with my customized operating modes for the winch and setup.
the plan,assuming these are acceptable is to use 2 of them for an h bridge circuit along with other components the ideal end result is a much better controller which can stay within the small size of the old pcb.
now the 08m2 will get its power from the rc reciever aux channel i use for winch control, the speed controller bec is supplying 6v to the reciever and this will be dropped down to just over 5v for the 08m2 with a couple of diodes, i know this works as i made a 6 transistor h bridge circuit for the winch but its not up to the job of coping with winching in under almost stall conditions so thats why i need to look at a beefier circuit.
the winch motor itself is being run from a 3 cell lipo pack(11.1v) which gives more grunt available but also increases the stall current to approx 1.1A though not without a good fight to keep going before stall but for the most part the current varies winching in from 400-580 ma.
due to the difference between the 08m2 power needs and the winch running higher i know that the highside of the h bridge will need to be switched by an npn to keep the high v+ of the winch supply away from the 08m2's pins as was done with the transistor circuit but never playing with mosfets before im still a bit confused after much forum and internet searching about the mosfets gate in respect to its connection to the picaxe pin.
i know that we use resistors to base on transistors to limit the current to protect the picaxe and i assume also the base of the tranny but do i still need to use a resistor on the gate of the mosfet to protect one or both?
also im still unsure completely about the highside switching, can i use an npn transistor to pull the highside gate low when i need to turn it on and if so do i need to worry about the transistors max current rating being exceeded if i switch a mosfet that can potentially draw way more current?
sorry for the ramblings but after trawling so many different sites and reading im definately still confused about a few things, so far to date i have only ever let the magic smoke out of a resistor and want to keep that good streak going, especially with my small supply of picaxe variants lol.
any insights/tips/ideas are greatly appreciated and welcomed.
tony
so firstly the mosfet i was looking over is a dual channel n and p soic8 package,
datasheet: View attachment FDS8958A.pdf
now the project is to replace my old and finally dead winch controller for an rc trailtruck/rock crawler which will also allow me to include an 08m2 soic with my customized operating modes for the winch and setup.
the plan,assuming these are acceptable is to use 2 of them for an h bridge circuit along with other components the ideal end result is a much better controller which can stay within the small size of the old pcb.
now the 08m2 will get its power from the rc reciever aux channel i use for winch control, the speed controller bec is supplying 6v to the reciever and this will be dropped down to just over 5v for the 08m2 with a couple of diodes, i know this works as i made a 6 transistor h bridge circuit for the winch but its not up to the job of coping with winching in under almost stall conditions so thats why i need to look at a beefier circuit.
the winch motor itself is being run from a 3 cell lipo pack(11.1v) which gives more grunt available but also increases the stall current to approx 1.1A though not without a good fight to keep going before stall but for the most part the current varies winching in from 400-580 ma.
due to the difference between the 08m2 power needs and the winch running higher i know that the highside of the h bridge will need to be switched by an npn to keep the high v+ of the winch supply away from the 08m2's pins as was done with the transistor circuit but never playing with mosfets before im still a bit confused after much forum and internet searching about the mosfets gate in respect to its connection to the picaxe pin.
i know that we use resistors to base on transistors to limit the current to protect the picaxe and i assume also the base of the tranny but do i still need to use a resistor on the gate of the mosfet to protect one or both?
also im still unsure completely about the highside switching, can i use an npn transistor to pull the highside gate low when i need to turn it on and if so do i need to worry about the transistors max current rating being exceeded if i switch a mosfet that can potentially draw way more current?
sorry for the ramblings but after trawling so many different sites and reading im definately still confused about a few things, so far to date i have only ever let the magic smoke out of a resistor and want to keep that good streak going, especially with my small supply of picaxe variants lol.
any insights/tips/ideas are greatly appreciated and welcomed.
tony