I'm looking to build a much better tachometer circuit for my dads Torino. I did a very basic circuit that uses no transistors but it's slow, not very accurate and kinda sucks and I had to modify it to even work right. I want a good circuit but can't find anything online. It has a MSD 6 ignition installed. I'm using the digital output signal from it for this. I will at some point take my oscilloscope to that and see what pulses per minute and rpm there is. For now assume mutilple pluses per engine cylinder as its like a hot fire multiple sparks per cylinder for cleaner burn? I think I read that online. So I need it to take say 3 pluses per cylinder and like 4 cylinders per rotation. I need it to go to a 1ma needle. It doesn't need to be the best just good, small and easy to do. That way it can fit inside the tight tachometer casing. It's a rare and valuable ribbon tachometer so I need to take care. They cost $400 untested! Insane.
I've seen those 555 circuits and thought about it but they're all taking their inputs from the coil! I don't have that option here. And I can't find a circuit with a digital input. Only ever the coil. So if I can get some help that would be awesome. I will go through my IC chips I have and put a list here. I know some will be way overkill but what else I'm a going to use them on? I'm more into vacuum tubes and doubt I'll build much else with them. So I'll list them later tonight and see about getting the MSD digital output captured on my oscilloscope. I upgraded that so now it's only 20+ years old instead of 55+ years old. It's a Tektronix 2232, old was a Tektronix Type 317.
So for now assume 3 pluses per cylinder until I see otherwise. MSD is so kind to to give the info on their digital output signal. If only they would. That would make this easier starting off. Well at least that part will only take a couple minutes and guessing an rpm of 750 idle that will give a starting point for this. I believe it's a 5v p-p signal from it. I'll confirm later tonight or this weekend at latest. Thanks
I've seen those 555 circuits and thought about it but they're all taking their inputs from the coil! I don't have that option here. And I can't find a circuit with a digital input. Only ever the coil. So if I can get some help that would be awesome. I will go through my IC chips I have and put a list here. I know some will be way overkill but what else I'm a going to use them on? I'm more into vacuum tubes and doubt I'll build much else with them. So I'll list them later tonight and see about getting the MSD digital output captured on my oscilloscope. I upgraded that so now it's only 20+ years old instead of 55+ years old. It's a Tektronix 2232, old was a Tektronix Type 317.
So for now assume 3 pluses per cylinder until I see otherwise. MSD is so kind to to give the info on their digital output signal. If only they would. That would make this easier starting off. Well at least that part will only take a couple minutes and guessing an rpm of 750 idle that will give a starting point for this. I believe it's a 5v p-p signal from it. I'll confirm later tonight or this weekend at latest. Thanks