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

[Mike]

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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Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
http://niche.iinet.net.au