Post by thread:[EE]: distributor point interface to pic

Hi all!, first of all, i'm not an EE guy, so.... i have played for some months with an full analog electronic ignition in my old point style car distributor. i want to make the next move to a more intelligent circuit, where i can adjust dwell, advance, etc, keeping the points in case of emergency. i have search the web and the archive, and i have'nt found any real interface between the 12 v world and the 5 v, thats works well in low voltage situations (cranking), and keep noise away from circuit / inputs pin. please no hall efect sensor, and optoelectronics will be an alternative if the led is driven directly by the points (this sound me like the most robust solution, but apparently none is implementing a digital input in this way, why?) any help will be appreciated thanks in advance RVP. ____________________________________________

--- Rodrigo Valladares P <spam_OUTr-valladTakeThisOuTunete.cl> wrote: > distributor. i want to make the next move to a more > intelligent circuit, > where i can adjust dwell, advance, etc, keeping the > points in case of > emergency. <snip> > inputs pin. please no hall efect sensor, and > optoelectronics will be an > alternative if the led is driven directly by the > points (this sound me > like the most robust solution, but apparently none > is implementing a > digital input in this way, why?) -------------------------------------- IIRC, ignition points need a fairly good current through them so they self clean - a few ma for a led wouldn't be enough? Points also have very little voltage drop across them, electronic ignitions generally have lower resistance coils to allow for this. Pre 1981 BMW motorcycles had points, and there is (was?) kits available that replaced the points plate with an electronic replacement. The old plate (with the points on it) coud be carried and swapped in if neccesary... ____________________________________________

> -----Original Message----- > From: .....piclist-bouncesKILLspam@spam@mit.edu [piclist-bouncesKILLspammit.edu] On Behalf > Of Rodrigo Valladares P > Sent: Friday, November 05, 2004 4:20 AM > To: Microcontroller discussion list - Public. > Subject: [EE]: distributor point interface to pic > > Hi all!, > > first of all, i'm not an EE guy, so.... i have played for some months > with an full analog electronic ignition in my old point style car > distributor. i want to make the next move to a more intelligent circuit, > where i can adjust dwell, advance, etc, keeping the points in case of > emergency Keeping the "points" will result in keeping all the problems associated with "points" > i have search the web and the archive, and i have'nt found > any real interface between the 12 v world and the 5 v, thats works well > in low voltage situations (cranking), and keep noise away from circuit / > inputs pin. please no hall efect sensor, and optoelectronics will be an > alternative if the led is driven directly by the points (this sound me > like the most robust solution, but apparently none is implementing a > digital input in this way, why?) The distributor contains mechanical points, a centrifugal advance and a vacuum advance all of which are inaccurate and unreliable compared to a well designed electronic ignition Your mechanical distributor gives an output where it thinks the best place for the spark is, from this information are you going to guess where TDC is then work out where you want your spark? That's why you've found no apps using the points > any help will be appreciated find a way to take an output from the crank with a hall effect keep an open mind, the crank has two ends, is the front pulley an option for a sensor? > thanks in advance > > RVP. PC ____________________________________________

{Quote hidden}> >> -----Original Message----- >> From: .....piclist-bouncesKILLspam.....mit.edu [EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu] On > Behalf >> Of Rodrigo Valladares P >> Sent: Friday, November 05, 2004 4:20 AM >> To: Microcontroller discussion list - Public. >> Subject: [EE]: distributor point interface to pic >> >> Hi all!, >> >> first of all, i'm not an EE guy, so.... i have played for some months >> with an full analog electronic ignition in my old point style car >> distributor. i want to make the next move to a more intelligent > circuit, >> where i can adjust dwell, advance, etc, keeping the points in case of >> emergency > > Keeping the "points" will result in keeping all the problems associated > with "points" May be, but is the simplest solution {Quote hidden}> >> i have search the web and the archive, and i have'nt found >> any real interface between the 12 v world and the 5 v, thats works > well >> in low voltage situations (cranking), and keep noise away from circuit > / >> inputs pin. please no hall efect sensor, and optoelectronics will be > an >> alternative if the led is driven directly by the points (this sound me >> like the most robust solution, but apparently none is implementing a >> digital input in this way, why?) > > The distributor contains mechanical points, a centrifugal advance and a > vacuum advance all of which are inaccurate and unreliable compared to a > well designed electronic ignition i can replace centrifugal advance and points, with a rpm v/s advance table and hall sensor o opto, but for vacuum advance i need a map sensor? or there exists another alternative? {Quote hidden}> > Your mechanical distributor gives an output where it thinks the best > place for the spark is, from this information are you going to guess > where TDC is then work out where you want your spark? > That's why you've found no apps using the points > >> any help will be appreciated > > find a way to take an output from the crank with a hall effect > keep an open mind, the crank has two ends, is the front pulley an option > for a sensor? yes, but one full turn of distributor is two turns of crank, if i understand well this, i must fire two cilinders each time, it forces me to the third part of the project, where i want to eliminate the upper part of distributor, rotor and hv leads and replace all with three coils (6 cyl). perhaps is not a bad idea, i will see how i can put a sensor on front pulley. lots of thanks! > >> thanks in advance >> >> RVP. > > > PC > > ______________________________________________

A MAF sensor is the method commonly used. You can still use the distributor for the HT side so enabling you to use only one coil and not worry about which of the two crank revs is which And if your going for three coils it doesn't matter Now if it was a 5 cyl I personally would keep the points as a ref input It would be easier than fitting a sensor on the cam If you do fit a sensor on the crank and interface to the points then would also be possible to 1/ display what the mechanical system parameters are 2/ get an approx vacuum value 3/ the difference between the mechanical and electronic timing Have you visited Tony Nixon's site he did an electronic ignition a while back ? PC > {Original Message removed}