Well thank you too really, for not taking it the wrong way.
The gate like that is inverter with one small npn and a pullup and output taken after pullup, so when small transistor is not driven it is closed and the inverter output is 12v into the bigger mosfet gate and hence the bigger power mosfet is always conducting coz its gate is always relaxing at 12v. So with mcu turned off, power to hotend or bed is always on. Only when small transistor is actively driven, it pulls the 10k pullup to ground, the output is 0v at the gate of power fet, and only then the big power mosfet starts to close. Imo, this is a dangerous way to work, prone to meltdown.
Yes you are right about that its not pullup for sleep, i saw it like one and jumped at it with prejudice :) However is probably better to have pullups on pins than to simply tie them to vcc as latter does not imply any current limiting and then perhaps chips can burn easier. But its a matter of opinion ofc.
I dont think D2 is the other way around, if i got this correctly then in reverse position will shorts the voltage to gnd. As it is, its reverse biased and points from gnd to v+ in forward. So it only opens if the power is connected wrong polarity and could blow fuse this way, or else if its a transient supressor which breaksdown to put higher voltages to ground. These are my suppositions but a 4004 wont do much either way.
I thought of lpc board being on top coz of mbed ones, and it generally makes more sense to me to have the board easily available than hidden underneath. For example the boards usually have some features on it that need no duplication: headers, including icsp ones, reset button, leds, etc. If the board is on the bottom and in a position that these cant be accessed, then need to duplicate things like that, which imho isnt great. Dunno about lpc, but for example arduino mega has its own leds, icsp connector, reset button, etc, but because ramps covers them, then its required to duplicate them all over again. So imo, leaving the board fully accessible is way better. Like the mbed modules, or wiring. At least in principle, and just my personal perspective. Or for ease of hacking things. In the big picture ofc i can understand for commercial purposes some may worry the board area underneath if not used may be wasted, and since pcb are paid by area then perhaps duplicating some basic features may be a smaller cost than such a board space cost.
I think polyfuse when active can get hot, and probably better upwards can get better ventilated. But probably more a preference thingy, dunno how much it would count in the end, if these want to burn then will probably burn in either position same way. I would put them on top, even if just to be sort of visible or "touchable" and be able to catch the user's eye when have problems.
I2C pullups theoretically depend on that line capacitance and speed mode of i2c, you can put them there or you can leave them out, doesnt rly matter much coz a typical i2c accessory board should have place for such pullups, but only one set is needed. If its convenient put them, like if you have vcc right nearby, else its ok to leave them out.
The gate like that is inverter with one small npn and a pullup and output taken after pullup, so when small transistor is not driven it is closed and the inverter output is 12v into the bigger mosfet gate and hence the bigger power mosfet is always conducting coz its gate is always relaxing at 12v. So with mcu turned off, power to hotend or bed is always on. Only when small transistor is actively driven, it pulls the 10k pullup to ground, the output is 0v at the gate of power fet, and only then the big power mosfet starts to close. Imo, this is a dangerous way to work, prone to meltdown.
Yes you are right about that its not pullup for sleep, i saw it like one and jumped at it with prejudice :) However is probably better to have pullups on pins than to simply tie them to vcc as latter does not imply any current limiting and then perhaps chips can burn easier. But its a matter of opinion ofc.
I dont think D2 is the other way around, if i got this correctly then in reverse position will shorts the voltage to gnd. As it is, its reverse biased and points from gnd to v+ in forward. So it only opens if the power is connected wrong polarity and could blow fuse this way, or else if its a transient supressor which breaksdown to put higher voltages to ground. These are my suppositions but a 4004 wont do much either way.
I thought of lpc board being on top coz of mbed ones, and it generally makes more sense to me to have the board easily available than hidden underneath. For example the boards usually have some features on it that need no duplication: headers, including icsp ones, reset button, leds, etc. If the board is on the bottom and in a position that these cant be accessed, then need to duplicate things like that, which imho isnt great. Dunno about lpc, but for example arduino mega has its own leds, icsp connector, reset button, etc, but because ramps covers them, then its required to duplicate them all over again. So imo, leaving the board fully accessible is way better. Like the mbed modules, or wiring. At least in principle, and just my personal perspective. Or for ease of hacking things. In the big picture ofc i can understand for commercial purposes some may worry the board area underneath if not used may be wasted, and since pcb are paid by area then perhaps duplicating some basic features may be a smaller cost than such a board space cost.
I think polyfuse when active can get hot, and probably better upwards can get better ventilated. But probably more a preference thingy, dunno how much it would count in the end, if these want to burn then will probably burn in either position same way. I would put them on top, even if just to be sort of visible or "touchable" and be able to catch the user's eye when have problems.
I2C pullups theoretically depend on that line capacitance and speed mode of i2c, you can put them there or you can leave them out, doesnt rly matter much coz a typical i2c accessory board should have place for such pullups, but only one set is needed. If its convenient put them, like if you have vcc right nearby, else its ok to leave them out.