Tach signal
Melting Slicks
Joined: May 2000
Posts: 2,148
Likes: 1
From: Chandler AZ
Re: Tach signal (Sliding)
It's driven off the neg coil primary and fires every spark. So 8 times per 2 revolutions: frequency is RPM * 4.
This side of the coil is grounded to charge the primary, then opened to collapse the field and fire a spark. I think the spikes are negative going from this coil flyback. Looks like the stock system never puts more than 12V across the primary, so I'll guess -12V pulses?
Seems really weak though; aftermarket ignitions deliver around 500V to the coil primary...
This side of the coil is grounded to charge the primary, then opened to collapse the field and fire a spark. I think the spikes are negative going from this coil flyback. Looks like the stock system never puts more than 12V across the primary, so I'll guess -12V pulses?
Seems really weak though; aftermarket ignitions deliver around 500V to the coil primary...
