Page 1 of 1
#1 V12 Tacho - Signal Input
Posted: Fri Sep 04, 2009 9:55 am
by AussieEtype
I want to put a V12 tacho into another vehicle but am not sure where the tacho takes it rev input from. Is it direct from the coil like older cars, a tacho generator like early e-types, from a spark plug, or from the ignition amplifier (in which case does it count every pulse or one in 12 etc).
Also - does anyone know if the V12 tacho be modified to suit a V8.
Thanks
Garry
#2
Posted: Fri Sep 04, 2009 2:41 pm
by e-bygum
Garry
The series 3 tacho takes it's input from the amp via the ballast resister pack. Can't help you with the other questions- sorry.
#3
Posted: Fri Sep 04, 2009 11:56 pm
by AussieEtype
Thanks Pete - I assume that is the same as an older tacho connected to the coil - counting each pulse generated by points (in non electronic ignition cars).
Garry
#4
Posted: Sat Sep 05, 2009 12:30 pm
by e-bygum
garrycol wrote:Thanks Pete - I assume that is the same as an older tacho connected to the coil - counting each pulse generated by points (in non electronic ignition cars).
Garry
I don't know if you can assume that. The wiring on mine has been altered at some time and I don't know why. I still have the Opus, ballast etc. but there is no feed from the amp through the ballast to my tacho. Instead the tacho is fed from coil -ve through what I believe is a diode. I know that several other owners have this same set-up but I have not been able to find out why. It has been suggested to me that my tacho may have been altered to allow it to work from the coil, I don't know. I have also heard it said that the amp produces a square wave form signal for the tacho, I don't know how this compares to the signal for the coil
#5
Posted: Sat Dec 05, 2009 11:57 am
by Jagcats
Series 3 V12 takes it Tacho signal from the Ignition coil via the ballast pack or on some cars via a separate resistor, this is rated at around 10 K ohms. It counts every pulse from the coil and therefore will only work on a 12 cylinder engine. It would be difficult to calibrate it to work on an 8 cylinder engine.
#6
Posted: Sat Dec 05, 2009 2:35 pm
by e-bygum
Jagcats wrote:Series 3 V12 takes it Tacho signal from the Ignition coil via the ballast pack or on some cars via a separate resistor, this is rated at around 10 K ohms. It counts every pulse from the coil and therefore will only work on a 12 cylinder engine. It would be difficult to calibrate it to work on an 8 cylinder engine.
What is the purpose of the white/blue lead from the Opus amp to the ballast resister connection marked 'tach', if the tach receives it's input signal from the coil?