Attaching the Tach to two active coils at the same time will give incorrect and or erratic readings even if the diodes are used. It will count the pulses from both coils and add them together unless they are in absolutely perfect synchronization. The smallest difference in pulse timing will cause problems. It would be better to connect the Tach to only one coil at the time through a SPDT switch. Using a Center OFF switch would allow complete disconnection from the coils in case of Tach failure. ----- Original Message ----- From: "Martindale Family" <johnja...@optusnet.com.au> To: "Mark Jones" <flyk...@wi.rr.com>; "KRnet" <kr...@mylist.net> Sent: Wednesday, October 11, 2006 7:41 AM Subject: Re: KR> Tach hook up question.
> Aye, but what happens if either diode fails and conducts both ways. Is > your > active coil then driven by two sets of points going to ground at the same > time. If the points are slightly out in gap/alignment on lobes is dwell > time > extended or ignition timing altered. Hmmmm. > > I reckon it's easier and more reliable to do away with a coil tacho all > together and use a tooth counter sender off the ring gear then tacho > failure > won't stop your ignition. > > > John Martindale > 29 Jane Circuit > TOORMINA NSW 2452 > AUSTRALIA > > phone: 61 2 66584767 (H) > 61 2 66869075 (W) > mobile: 0403 049990 > email: johnja...@optusnet.com.au > web: www.members.optusnet.com.au/johnjanet/Martindale.htm > > ----- Original Message ----- > From: "Mark Jones" <flyk...@wi.rr.com> > To: "KRnet" <kr...@mylist.net> > Sent: Wednesday, October 11, 2006 9:05 PM > Subject: Re: KR> Tach hook up question. > > >> Thanks Colin. That explanation says it all and makes it very >> clear.......... > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
