12-20-2020, 03:57 AM
Hey there!
So I tried hooking up 12V to the tach and a mosfet (since that's what I had on hand), as a switch, pulling the tach wire to ground through a resistor when turned on by the ECU signal wire. The needle does jump a tiny bit only when cranking, as soon as the engine starts, the needle stands still.
My Chinese scope has arrived too, but I don't really know how to use it yet. I wrote a simple arduino program using the "tone" command. It should output a 5V signal at a set frequency and 50% duty cycle. I set it to 250Hz for the test and when I hooked up the scope and pressed the "auto adjust" button I got some funny results
here:
https://photos.app.goo.gl/rRjqmkx7gT6qkiPp9
Why does it display a negative pulse and nothing near a square wave? I also tried manually setting the pin to output 5V, then 0V with a manual delay and I got pretty much the same result. Either this scope is crap, or I can't set it up right.(I'm leaning more towards me being dumb).
What could be causing that?
So I tried hooking up 12V to the tach and a mosfet (since that's what I had on hand), as a switch, pulling the tach wire to ground through a resistor when turned on by the ECU signal wire. The needle does jump a tiny bit only when cranking, as soon as the engine starts, the needle stands still.
My Chinese scope has arrived too, but I don't really know how to use it yet. I wrote a simple arduino program using the "tone" command. It should output a 5V signal at a set frequency and 50% duty cycle. I set it to 250Hz for the test and when I hooked up the scope and pressed the "auto adjust" button I got some funny results
here:
https://photos.app.goo.gl/rRjqmkx7gT6qkiPp9
Why does it display a negative pulse and nothing near a square wave? I also tried manually setting the pin to output 5V, then 0V with a manual delay and I got pretty much the same result. Either this scope is crap, or I can't set it up right.(I'm leaning more towards me being dumb).
What could be causing that?