EDIS Grounding Capacitor Specs

[Homer Jones]

In the Megamanual wiring diagram for EDIS Ignition Control with Megasquirt II, there is a 25 Micro-farad capacitor between connector pin 8 (and EDIS 6 coil connector 4) and ground. I can't find any info about what kind of capacitor to use. It looks as if it is for noise suppression or possibly to control back-EMF. So, could I simply use a capacitor out of a breaker point distributor? If not, I need a little coaching.

[Homer Jones]

I believe I found the answer. The forum's search feature did not give the results I needed, but I probably used faulty search criteria. After posting the question, I did an eyeball search and found the capacitor is for noise suppression. My plan is to use a generic noise suppression condenser. Please let me know if I'm way off base.

[kjones6039]

My plan is to use a generic noise suppression condenser. Please let me know if I'm way off base.

Just for the record, capacitor and condenser are pretty much synonymous. The noise suppression caps attached to the EDIS coils are not required, but it won't hurt to drop in a ~25 mf cap if you like. The correct cap for EDIS are readily available from your local wrecking yard.

Ken

Great last name, btw!

[kjones6039]

Homer,

Just re-read your first post.........

Yes, a capacitor from a dizzy would work nicely!

Ken

[Homer Jones]

Thanks for the quick reply, Ken. You are right about condenser vs capacitor. Exactly the same thing. However, condenser seems to be the accepted term if your hand fits a wrench, and capacitor if you say things like E = IR. Then there are those who can hold a wrench and an ohm meter at the same time. Possibly named Jones? Along those lines, I just returned from AutoZone (a local parts store). You should have been there when I ask for a Radio Noise Suppression Capacitor. (Silence except for the sound of crickets).

[trakkies]

IIRC, the value of the type used for points is rather lower than one you'd use for RFI suppression. Something like 0.1uF for Lucas 12v systems. It formed a tuned circuit as well as extending points life.

There was also a second cap (optional) fitted between coil supply and ground, usually added when you fitted a radio. In those days the only electronics in a car. The EDIS one is for the same reason - but to help prevent RFI causing problems with the various ECUs in cars, including the EDIS one.

Beauty of the correct EDIS one is it fits under one of the coil fixing screws, so looks quite neat. I'd be tempted to find out the Ford part number and try and get an OEM replacement for this reason.

[Homer Jones]

Trakkies, I think you hit the nail on the head. What little I can find on capacitance agrees with your recollection. The points condensers seem to be in the 0.1 to to 0.15 uF range. The ones for RFI suppression are a good deal larger, but hard to find the actual spec. I like your suggestion to get a Ford component. Since all the other bits are used, I expect a junk yard capacitor will be just as good. After all, how much stress would an RFI capacitor receive under normal conditions?

[DonTZ125]

it won't hurt to drop in a ~25 mf cap if you like.

Are you looking for noise suppression, or powering a railgun?!

I believe the EDIS caps are 25uF ...

[Homer Jones]

Wouldn't a railgun need something more like 25MF as opposed to 25mF?

[DonTZ125]

A small railgun ...