Page 1 of 1

EDIS Capacitor Size???

Posted: Thu Dec 22, 2011 3:27 pm
by Tailwind
I need to add the capacitor to the EDIS circuit. The manual calls for a 25 uF connected to the 12 Volt side of the coil pack. I found a suggestion fro Mat Cramer that an old-time condenser for a distributor would work.

My question is: is there a misprint in the manual? A condenser for my Spitfire engine would be 0.18 to 0.25 mF. If the 'u' and the 'm' both stand for "micro" then The ignition condenser is only 1/100 the size called for.

Or am I reading this wrong???

Bill

Re: EDIS Capacitor Size???

Posted: Thu Dec 22, 2011 4:10 pm
by Tailwind
OOPS Brain Cramp!! The 'm' stands for 'milli' as in 10^-3 not 'micro' 10^-6.

It's just different ways of saying the same thing.

:oops:

Sorry about that.

Re: EDIS Capacitor Size???

Posted: Fri Dec 23, 2011 1:10 am
by trakkies
On a points system, the cap across the points forms part of a tuned circuit, so has a fairly critical value. With EDIS, is is merely to help remove any interference spikes etc, so likely not so. But I would try and get the correct part - they're common enough in scrap yards, and since you'll also need the coil plug can be obtained at the same time. I suppose you could use a cap from an electronics supplier if you knew the exact type and spec. But that would be more difficult to mount.

Re: EDIS Capacitor Size???

Posted: Fri Dec 23, 2011 4:14 am
by Tailwind
Thanks for the response. Actually, the EDIS is already installed and has been functioning for a couple of years. I've been using a Megajolt Lite to run it and this does not seem to require the capacitor. At least is says that in the documentation. Now that I'm changing to a Megasquirt, I presume it is prudent to add it. The points condenser would be bigger than necessary, but readily available and easily mounted. It's more for convenience than anything else.

Thanks, again.

Bill

Re: EDIS Capacitor Size???

Posted: Fri Dec 23, 2011 7:03 am
by trakkies
My feeling is that if it worked with a MegaJolt sans cap, it will be OK with MS too. As I said, it's there to help remove possible interference. Maybe to the car radio as well as other car electronics. Or, indeed, to other's electronics not part of your car.

Re: EDIS Capacitor Size???

Posted: Sat Dec 24, 2011 4:53 am
by Tailwind
That's a distinct possibility, Trakkies. I do have a wiring diagram for a 1995 ford Escort (USA version) that shows the capacitor as a radio noise filter. In my particular case, the ignition noise would be the least of my problems trying to listen to a radio, not that I have one. My Locost is pretty noisy (93dB running down the road) so the radio wouldn't stand much chance of being heard.

My feeling right now is that the capacitor will do no harm, and will allow me to connect the power lead running from the Megajolt box to something, rather than leave a 'hot' wire unterminated in the bundle.

Thanks for the insights.

Bill