[Diy_efi] Re: new EFI controller

[Klaus R Schambeck]

Hi Marcell !!!

Sorry about the confusion with the original mesage and 2 responses.

My original comment was to use a zener plus a normal diode in the back emf
part to provide a larger back emf voltage to burn off the back emf energy
faster.
Yes the normal diode in the zener and diode combination should be not too
slow.

Best regards, KLAUS

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of Marcell Gal
Sent: Tuesday, March 11, 2003 11:02 PM
To: List for general do-it-yourself EFI talk
Cc: efi at caffrey.dk
Subject: [Diy_efi] Re: new EFI controller


Hi Klaus,

>> to make sure they switch off fast put a zener into the back EMF diode
path
>> (A higher voltage during the injector energy discharge makes it faster)
>
> Yep, the consensus seems to be zener or shottky...
> I'd probably say shottky, though I'd have to look into it slightly more...

Alexei suggested rectifying diode (fast or ultrafast).
Not as sensitive, as a schottky.
Or using a controlled flyback, as yourself used in
the PWM limiting app.

The AVR megasquirt is great and here: (thanx for the hint)
http://caffrey.dk/megasquirt/
Look at schematic page 6. T3 is a power pnp,
flyback diode is connected to T3 emitter, collector
connected to ground (
(Michael, may be it should connect to power for efficiency
and cool T3 operation!!!)
base offset is set by a resistor and zener.
I would also use a power resistor (~20..47 Ohm)
parallel with T3 CE. I think this is better than
a power zener. (Especially if we want to control it
for PWM limiting)

 Marcell

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