Dirty Power Issue?
a friend of mine , have been working on reading sensors in old jeep cj5 , ran snag.
i built voltage regulator circuit lm1084-adj, outputting 9v powering on barrel jack. the output hot-line switched toggle switch. this powers arduino uno, in turn powers 20x4 character lcd screen. sensors measuring fuel tank potentiometers , engine temperature sensor (thermistor). to measure resistance i'm using voltage divider off of 5v header. the 5v has 2.4k resistor going each analog pin goes pot/thermistor ground.
when regulator power switch off, , arduino/screen powered on usb connected laptop, values fine. however when power coming voltage regulator circuit, powers fine, uno , screen communicate, analog pins read 0. if barrel jack disconnected completely, value maxes, expected disconnected ground.
i'm curious if people think issue voltage regulator used, there no isolation. i've never used isolation needed measure referencing power source's ground, require. is there such thing?
one interesting/concerning thing happened was: power , ground coming off keyswitch, (i'm pretty sure they're tied straight battery, i'll verify next time head on there) when key turned engage starter, arduino , lcd screen both lit up. this regulator switched off position, ground straight through connection. any thoughts?
i built voltage regulator circuit lm1084-adj, outputting 9v powering on barrel jack. the output hot-line switched toggle switch. this powers arduino uno, in turn powers 20x4 character lcd screen. sensors measuring fuel tank potentiometers , engine temperature sensor (thermistor). to measure resistance i'm using voltage divider off of 5v header. the 5v has 2.4k resistor going each analog pin goes pot/thermistor ground.
when regulator power switch off, , arduino/screen powered on usb connected laptop, values fine. however when power coming voltage regulator circuit, powers fine, uno , screen communicate, analog pins read 0. if barrel jack disconnected completely, value maxes, expected disconnected ground.
i'm curious if people think issue voltage regulator used, there no isolation. i've never used isolation needed measure referencing power source's ground, require. is there such thing?
one interesting/concerning thing happened was: power , ground coming off keyswitch, (i'm pretty sure they're tied straight battery, i'll verify next time head on there) when key turned engage starter, arduino , lcd screen both lit up. this regulator switched off position, ground straight through connection. any thoughts?
what max resistance of pot?
what resistance (hot , cold) of thermistor?
what resistance (hot , cold) of thermistor?
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