On Jul 2, 1:49 pm, Sjouke Burry <burrynulnulf...@[EMAIL PROTECTED]
>
>
> As soon as the ecm line gets diconnected from ground, a huge
> induction voltage is sitting on your device, blowing it to pieces.
> You need the protected divider I spoke of.
> The ignition coil acts as an auto transformer, and as soon as you
> break the current, you get a big volage across the 12volt winding.
> Not as bad as at the spark plug(thousands of volts), but bad enough.
> Thats why they use ~800 volt transistors to do the switching in the
> ecm unit.
O.k. Revising. Idea is separate 5 v supply for data logger and have
it's sensor ground tied to the switched ECM coil ground. Will this
work? See diagram below. Note Channel 1 on data logger. C1+
receives +5vdc
VCC
.------------------------------------.
| 11.5-13.8v DC |
|
|.----'
C|
C| .--------.
C| Switched Ground | |
|'--------------------' ECM |
| '----o---'
.-. |
| | |
| | |
'-' ===
.---->z----z<-| GND
|
|
|
| .----------.
| C1 - | |
VCC '------------ |
+ |DataLogger|
| | |
'---------------- |
5v DC C1+ '----------'
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
|
