Im sorry if this is in the wrong forum please move it if it needs to be moved.
I am working on a tach for a cnc spindle i am making. I am trying to make a ready made unit that is designed for the rc industry that is used to plug in parallel to the hall sensor for an electronic ignition unit. So i am having trouble trying to figure out what i need to do to make the tach work without the ignition unit.
So the tach is rated for 3.3v to 12v dc. I will be running it on 5v. My trouble shooting thus far has been taking voltage readings to try and figure out what is going on. If i hook the tach directly to the battery and sensor the tach will initialize and show 0 rpm but no mater how fast i spin the magnet over the sensor i do not get a reading on the tach if i hook it back up with the ignition everything works correctly.
so with the ignition unit powered by a 4 cell nicad:
v+ is 4.8v
signal no magnet is 4.8v
signal with magnet is 0v
with the sensor plugged directly into the battery:
v+ is 4.8v
signal no magnet is 0.7v
signal with magnet 0v
plugging my test lead directly into the sensor lead on the ignition unit without the hall sensor i get:
v+ 4.8v
signal 4.8v
i tired applying pos voltage to the signal line but it still did not work. i think i may need an amplifier on the signal line to bring the voltage up to 5v but im not sure. thank you for your help.
Attached is a pic of the unit i am working with
I am working on a tach for a cnc spindle i am making. I am trying to make a ready made unit that is designed for the rc industry that is used to plug in parallel to the hall sensor for an electronic ignition unit. So i am having trouble trying to figure out what i need to do to make the tach work without the ignition unit.
So the tach is rated for 3.3v to 12v dc. I will be running it on 5v. My trouble shooting thus far has been taking voltage readings to try and figure out what is going on. If i hook the tach directly to the battery and sensor the tach will initialize and show 0 rpm but no mater how fast i spin the magnet over the sensor i do not get a reading on the tach if i hook it back up with the ignition everything works correctly.
so with the ignition unit powered by a 4 cell nicad:
v+ is 4.8v
signal no magnet is 4.8v
signal with magnet is 0v
with the sensor plugged directly into the battery:
v+ is 4.8v
signal no magnet is 0.7v
signal with magnet 0v
plugging my test lead directly into the sensor lead on the ignition unit without the hall sensor i get:
v+ 4.8v
signal 4.8v
i tired applying pos voltage to the signal line but it still did not work. i think i may need an amplifier on the signal line to bring the voltage up to 5v but im not sure. thank you for your help.
Attached is a pic of the unit i am working with
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