[Diy_efi] Key-On Power for 7730

[Tom Visel]

Use a cap in parallel with the diodes if there's a dead spot between ign 
1 and ign 2.  Customer had a Jeep with a weird switch that dropped out 
just long enough to make everything hiccup, and the diodes / cap were 
the fix.  It may keep your power on a touch longer than the key is on, 
but it hasn't been a problem on this project at least.

Rick McLeod wrote:

>Ign1 ------|>|------|
>                         |-------------- to 'Key-On' circuits
>Ign2 ------|>|------|
>
>Use 5Amp 100PIV diodes for the above, it will privide +12V (sans .7V for forward diode, which is insignificant) to the circuits that require power when cranking and running. I've done this many times, KISS is your friend!
>
>Hit your local RadioShack:
>Hit your local RadioShack:
>6A 50V Rectifier 4pack
>276-1661 for $2.49 per package
>
>
>
>----- Original Message ----
>From: Clair Davis <clair.davis at charter.net>
>To: diy_efi <diy_efi at diy-efi.org>
>Sent: Wednesday, September 27, 2006 9:40:41 PM
>Subject: [Diy_efi] Key-On Power for 7730
>
>
>Background... I've got a 69 Plymouth Valiant I'm multipoint-injecting with a
>7730 box.  I've got two wires left to run, and one of them is killin' me:
>Key On Power.
>
>On my old Plymouth, the ignition switch has 5 wires: BATT, START, ACC,
>IGN-1, and IGN-2.  IGN-1 is the "run" power to the coil, dropped down with a
>ballast resistor to keep the coil happy.  IGN-2 is 12V straight to the coil
>for hotter sparks while cranking.
>
>The IGN-1 circuit is DEFINITELY dead while cranking, and IGN-2 is ONLY hot
>while cranking.  Once the engine fires, you let up on the key, the switch
>rolls back to IGN-1 and you go on about your way.  Problem is, I can't tell
>how long the dead skip is in the transition between the two circuits.
>
>Is this a problem?  Seems like it might be, as the "key on" signal seems to
>be the trigger for the whole start-up routine with the ECM.  Is a GM
>ignition switch one where there is no break in the power from "run" to
>"start" and back, or am I overthinking things?  Mopar guys that run MSD
>ignitions splice IGN-1 and IGN-2 together for the MSD to work, but that's
>hardly the same animal.
>
>Thanks in advance!
>
>Clair
>
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>  
>