Mk1_Mark
|
| posted on 9/6/09 at 08:31 PM |
|
|
Zetec rev counter problem
Hey all. I am running a zetec on bike carbs and using esc for the ignition.
I am taking the feed for the rev counter from one side of the coil pack and am using an old smiths rev counter.
I am only getting what i believe to be a half reading on the rev counter though. What have other people done to get their rev counters to work and has
anyone else had problems?
I believe you can take a feed from both sides of the coil pack and then use diodes to join the signal wires but i can't seem to get hold of the
diodes to do this so am a bit stumped.
Thanks, Mark
|
|
|
|
|
whitestu
|
| posted on 9/6/09 at 08:48 PM |
|
|
Try Maplins for the diodes Maplins.
Doesn't the esc have a tacho output?
Stu
|
|
|
Mk1_Mark
|
| posted on 9/6/09 at 09:06 PM |
|
|
I've tried maplins and can only get hold of 2 of the diodes, the diodes i need are
2x 1N4004DICT-ND
1x 1N4746ADICT-ND (hard to get hold of)
the esc i am using doesn't have a tacho output, it came off a 1.3 mk5 escort with no tacho, although i do also have a esc set up off a 1.6cvh
mk5 escort (slightly different) and the loom is untaped in places and the tacho feed just seems to be wired to one side of coil pack which is why i
done mine like this 
|
|
|
Danozeman
|
| posted on 9/6/09 at 09:24 PM |
|
|
what ign have you got. the only way i could get mine to work with megajolt was from a pin on the edis4.
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
|
|
|
MikeRJ
|
| posted on 9/6/09 at 09:31 PM |
|
|
Any 18v or so zener diode will be fine, this is not a critical circuit. The idea is that the zener blocks the 12v from the un-energised coil, since
the tacho needs to see the voltage swing down to zero, or thereabouts. Since the flyback voltage from the coils will be of the order of 200-300
volts, a few volts difference on the zener isn't going to make any difference.
|
|
|
02GF74
|
| posted on 9/6/09 at 09:40 PM |
|
|
maplins do 1n4004 (forget the other numbers); do a search and this comes up as rectifier diode; also shown are 1n4001, 1n4002, 1n4003 - as far as
your application is concerned, all are interchangeable. (difference being the max reverse voltage).
1N4746a is a 18V zener - it shouldn't be necessary to use a zener.
|
|
|
MikeRJ
|
| posted on 9/6/09 at 11:14 PM |
|
|
1N4004 is the minimum spec, 1N4005 to 1N4007 are all ok as well. Anything lower in the series and reverse breakdown voltage is too low for ignition
coil applications.
Zener is usually needed, without it the voltage never reaches zero since with wasted spark there is always 12v on at least one coil.
|
|
|
Mk1_Mark
|
| posted on 11/6/09 at 06:30 PM |
|
|
quote:
Originally posted by MikeRJ
Any 18v or so zener diode will be fine, this is not a critical circuit. The idea is that the zener blocks the 12v from the un-energised coil, since
the tacho needs to see the voltage swing down to zero, or thereabouts. Since the flyback voltage from the coils will be of the order of 200-300
volts, a few volts difference on the zener isn't going to make any difference.
I'm a bit of a novice when it comes to electronics so thank you all for your help.
Would you be able to recommend an alternative for the 1x 1N4746ADICT-ND zenner diode?
Also when i phoned maplins about the other diodes they were available but after the 1N4004 there was a 2 choices with a different lettter following
this part of the number. What would this mean?
|
|
|
Macbeast
|
| posted on 12/6/09 at 06:46 PM |
|
|
Probably small casing difference. Nothing to worry about
[Edited on 12/6/09 by Macbeast]
|
|
|
Mk1_Mark
|
| posted on 14/6/09 at 10:44 PM |
|
|
Would this diode be ok as an alternative to the 1N4746ADICT-ND...
1N5352 BRL from maplins site
it just says it's 5w and is 15v, would this be ok?
i have also found some 18v zener diodes on the maplins site but they are 0.5w or 1.3w, i'm getting confused do i need the 18v diode or the
higher wattage?
what should i go for?
thanks for any help 
|
|
|
RoadkillUK
|
| posted on 15/6/09 at 02:57 PM |
|
|
Out of interest, we sorted out our rev counter yesterday (It's for the Acewell).
We connected the yellow wire from the Acewell dash to pin 11 on the EDIS 4. Hey presto ... instant Revs
Roadkill - Lee
www.bradford7.co.uk
Latest Picture (14 Sept 2014)
|
|
|
MikeRJ
|
| posted on 15/6/09 at 09:03 PM |
|
|
quote:
Originally posted by Mk1_Mark
Would this diode be ok as an alternative to the 1N4746ADICT-ND...
1N5352 BRL from maplins site
it just says it's 5w and is 15v, would this be ok?
i have also found some 18v zener diodes on the maplins site but they are 0.5w or 1.3w, i'm getting confused do i need the 18v diode or the
higher wattage?
what should i go for?
thanks for any help
The 15v one should be fine. There's no need for a 5 watt component (1.3W will eb fine), but they are physically larger with thicker wires so may
be easier to connect.
|
|
|
