Captain Haddock
Senior Member
I am considering taking a tacho signal from an alternator phase tap (thats what the tacho uses) to check to see if an engine is running before carrying out a start procedure, I was going to use an optocoupler/resistor before the picaxe but not yet sure of the unregulated ac output range, would a zener diode be good to control the voltage before the optocoupler or would that mess up the tacho reading?
No code or circuit diagram yet as it's early stage in the project (actually a full re-vamp of an existing one), I won't be able to check the tacho signal voltage range for a few weeks either.
I know it's a 12 pole alternator and fairly sure it runs at 2x or 2.5x crank speed so should be able to use pulsin to get an idea if it's running or not in a very quick time so should add an element of safety to an existing starting system, just need to condition the pulse to a safe level.
I could also use the same signal as an engine sync indicator.
No code or circuit diagram yet as it's early stage in the project (actually a full re-vamp of an existing one), I won't be able to check the tacho signal voltage range for a few weeks either.
I know it's a 12 pole alternator and fairly sure it runs at 2x or 2.5x crank speed so should be able to use pulsin to get an idea if it's running or not in a very quick time so should add an element of safety to an existing starting system, just need to condition the pulse to a safe level.
I could also use the same signal as an engine sync indicator.