hello, am new here, studied digital electronics 40 years ago, then became a programmer instead, am very rusty.
my application is a number of IOT sensors to be hand made using raspberry picoW boards.
bought a pack of A3144 hall effects without properly researching, these require 4.5v minimum, i should have ordered something 3.3 volt capable, however am wondering if i can still make these things work for me, with careful circuitry.
my application is various 24v and 12v boat engines, i need to monitor rpm and float position, etc, in various situations.
the 24v system will suffer peaks of up to 28v under charging conditions, and up to 16v in the 12v system.
the picoW boards will be powered from 3.3v buck converters tied to the battery rail, and will not have the 5v needed to power the hall effects.
can i just wire these transistors as open collector, and use a large enough pull up resistor, to the battery rail, as is commonly described for 12v systems?
can this work at 24v to 28v on the rail, or should i have more protection on the GPIO pins?
have seen advice on this forum to use one or more diodes in series to protect the GPIO, is this correct?
my hope is that, being open collector, the pullup power trick will not draw current when the transistor is quiescent - am i thinking correctly?
do i have any of this right, at all?
could anyone spare the time to help me work out a safe circuit for this?
i would not hold you responsible, i just do not want to have to blow up any boards, working out how to do this.
any advice very much appreciated, i hope i am explaining properly.
my application is a number of IOT sensors to be hand made using raspberry picoW boards.
bought a pack of A3144 hall effects without properly researching, these require 4.5v minimum, i should have ordered something 3.3 volt capable, however am wondering if i can still make these things work for me, with careful circuitry.
my application is various 24v and 12v boat engines, i need to monitor rpm and float position, etc, in various situations.
the 24v system will suffer peaks of up to 28v under charging conditions, and up to 16v in the 12v system.
the picoW boards will be powered from 3.3v buck converters tied to the battery rail, and will not have the 5v needed to power the hall effects.
can i just wire these transistors as open collector, and use a large enough pull up resistor, to the battery rail, as is commonly described for 12v systems?
can this work at 24v to 28v on the rail, or should i have more protection on the GPIO pins?
have seen advice on this forum to use one or more diodes in series to protect the GPIO, is this correct?
my hope is that, being open collector, the pullup power trick will not draw current when the transistor is quiescent - am i thinking correctly?
do i have any of this right, at all?
could anyone spare the time to help me work out a safe circuit for this?
i would not hold you responsible, i just do not want to have to blow up any boards, working out how to do this.
any advice very much appreciated, i hope i am explaining properly.