I have a KOSO digital dash and the RPM pick up wire is attached to No1 plug lead.
This works ok bit is a bit unsteady at tick over.
If I was to use this sheilded cable, am I right in thinking that the red wire only would wrap around the plug lead, and the other end of the red cable
to the clock, but with the coiled copper sheild fixed to an
earth?
Cheers
Andi
Yes, only earth at one end.
Capacitive couplin is a very poor method of sesnsing rpm (ie whats sugessted). It will stil be prone to false signals.
Better is inductive, use a ferrite snap on core.
wrap the wire arround the core (with no shield) about 3 -10 times).
Connect one wire to negative, the other to the dash.
Darren
Interesting..
So this kind of core
http://www.maplin.co.uk/module.aspx?TabID=1&criteria=usb&ModuleNo=32799&C=SO&U=Strat15
clips around the plug lead??
Cheers
Andi
That is interesting.
So lead from dash round ferrite core and the core on the plug lead ?
quote:Mine is a different dash but picks up the tacho the same way. The wire to the HT lead is two core and I was told to take the red core around the HT lead and the black to its own earth. Do I just take the red core around a ferrite on the HT lead?
Originally posted by turbodisplay
Capacitive couplin is a very poor method of sesnsing rpm (ie whats sugessted). It will stil be prone to false signals.
Better is inductive, use a ferrite snap on core.
wrap the wire arround the core (with no shield) about 3 -10 times).
Connect one wire to negative, the other to the dash.
Darren
The ferrite core works like a transformer. The ferrite core linked above will work.
The red wire is wrapped lengthways arround the core when opened (so alot of shield needs to be removed).
This will leave the dash connected on the other end of the red wire, the other end is open.
Connect (solder) the open end to the shield, connect one end of the shield to the earth (-ve battery) connection.
This is the same method that strobe timing lights use to detect sparks.
Darren
"Connect (solder) the open end to the shield, connect one end of the shield to the earth (-ve battery) connection."
I'm having a bit of a blonde moment here! I don't get this bit. Any chance of a sketch please?
Many thanks
Connect the shield to ground, either at the choke side or the dash side.
Will try to scan in a pic when i use the scanner later today.
Darren
I don't have a shield as such. It is just a very thin 2 core (fig 8) cable with a plug on one end. The plug fits into the loom on the back of the dash unit. The instructions suggest splitting the cores and then taking 3 to 10 turns of the red core around the HT lead and taking the black core to earth.
Just use one of the wires as a shield, the other for the signal.
Darren