Hi - I have a Hall effect sensor that features an open collector output but only capable of sinking 1mA of current. I want to drive an LED when the sensor is activated ie. output low. The output is pulled high via a 10k resistor to 5v when no magnetic field is present and pulled to ground via the collector output when triggered.
To drive an LED I figure I require a PNP BJT or FET (FDN340P or similar ). I’ve been reading Art of Electronics by Horowitz but I’m still stumped. As a BJT is current driven I’m not sure a BJT will be able to source enough current via the 1mA collector of the sensor to saturate. I have no idea how to choose a FET for this application. Does it definitely require a PNP ?
The other option, more cumbersome and totally overkill, is to use a SMD Attiny MCU but I’d rather try to understand the discrete electronics path before falling back to what I know and use the MCU.
To drive an LED I figure I require a PNP BJT or FET (FDN340P or similar ). I’ve been reading Art of Electronics by Horowitz but I’m still stumped. As a BJT is current driven I’m not sure a BJT will be able to source enough current via the 1mA collector of the sensor to saturate. I have no idea how to choose a FET for this application. Does it definitely require a PNP ?
The other option, more cumbersome and totally overkill, is to use a SMD Attiny MCU but I’d rather try to understand the discrete electronics path before falling back to what I know and use the MCU.
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