[Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?

[Daniel R. Nicoson]

there are a lot of ways to do it.  That's how I managed it.

Dan Nicoson


> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
> Behalf Of Mike
> Sent: Monday, May 23, 2005 12:14 PM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
>
>
> mmmmm, hard way to do it - imho
>
> I think there is an easier way
>
> <chuckle>
>
> Mike
>
>
>
> At 11:42 PM 23/05/05, you wrote:
> >To measure the pulse width of both a hi impedance and lo impedance (P&H)
> >injector I would take the signal between the injector and the computer's
> >transistor.  Use a comparator to create a nice clean square wave
> to measure.
> >
> >For a hi impedance injector you will see the voltage go from 12-14 volts
> >down to 0 - .6 volts as the injector opens.  The voltage will stay there
> >until the PW is over going back up.
> >
> >For the low impedance, you will see the voltage drop as
> described above and
> >then go back up to 8 volts or so for the hold portion.
> >
> >I would use a comparator to create your square wave.  Set the
> reference so
> >the comparator trips around 10 volts, this will ensure you can
> then measure
> >both hi & low impedance injector pulswidths.
> >
> >Go to Digi-Key.com and download the data sheet for a LM398.  This is a
> >sample & hold chip.  I used two in series to create a very nice steady
> >output on my project.  The data sheet will have example circuits
> to help you
> >figure the rest of the circuit out.  You will also need negative voltage
> >supply for use with this chip, I used the ICL7660.
> >
> >The 8 & 10 volts mentioned above are approximate.  You may find starting
> >voltages approaching these values (hope not) and that may or may not be a
> >problem for you.
> >
> >Also, be aware of the inductive spike as the injectors close or the P & H
> >goes from Peak to hold.  Your circuit may need some diode therapy to deal
> >with these.  I used a combination of high resistance on the
> input from the
> >injector line and some diodes to keep the spike out of my circuit.
> >
> >I have a write up on my sequential secondary injection system on
> my web site
> >www.myo-p.com  I used three channels of feed back on that circuit.
> >
> >Have fun.
> >
> >Dan Nicoson
> >
> >
> >> -----Original Message-----
> >> From: diy_efi-bounces at diy-efi.org
> [mailto:diy_efi-bounces at diy-efi.org]On
> >> Behalf Of gary
> >> Sent: Sunday, May 22, 2005 2:47 PM
> >> To: diy_efi at diy-efi.org
> >> Subject: Re: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
> >>
> >>
> >> (P)eak & (H)old.....  low impedance injector
> >> In reference to post below, the electronic kits and/or assembly
> >> books for such kits, for injector DC monitoring and to allow
> >> monitoring of P & H injectors can be can be obtained through
> >> AutoSpeed and Silicon Chip, both native of your country.
> >>
> >> GAS
> >>
> >> ----- Original Message -----
> >> From: "Mike" <niche at iinet.net.au>
> >> To: <diy_efi at diy-efi.org>
> >> Sent: Sunday, May 22, 2005 1:29 PM
> >> Subject: RE: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
> >>
> >>
> >> > At 08:32 PM 22/05/05, you wrote:
> >> > I have seen a kit that converts a P&H waveform into an equivalent
> >> > simple pulse waveform, expressly for the purpose of duty cycle
> >> > measurement.  It uses a dual op-amp IC and a handful of other small
> >> > components.  I have a magazine article that
> >> >
> >> > Sorry I'm missing something here - whats P & H ?
> >> > Did u mean Pulse Width ?
> >> >
> >> > Regards from
> >> > Mike Massen
> >> > Perth, Western Australia
> >> > VL Commodore Fuse Rail that wont warp or melt !
> >> > Twin Tyre rims and tyres for sedans
> >> > http://niche.iinet.net.au
> >> >
> >> > > describes it.  Let me know if you need more info, or contact me
> >> > > off-list if you'd like the name of the kit retailer.
> >> > >
> >> > >Cheers
> >>
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> >>
> >
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> Regards from
>
>
> Mike Massen
> Perth, Western Australia
> VL Commodore Fuse Rail that wont warp or melt !
> http://niche.iinet.net.au
>
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