SID shows instant voltage off, resulting in current decay !! Never checked with my scope, but this sounds correct for most solenoid drivers.
SID shows instant voltage off, resulting in current decay !! Never checked with my scope, but this sounds correct for most solenoid drivers.
Published wave form shows gradual voltage drop not instant off. Instant off would show last pulse going straight down to zero, it shows a curve back to zero. That tells me at least that voltage is reduced gradually. Over a split second but gradually.
The AMPS drop away in a curve to zero giving a soft drop.
that's what I said earlier !! . . . . . but given the coil must have a finite reactance, when the driver pack switches the voltage off (instantly) and the current decays, there must be some residual voltage across the coil. 
I assume if we try to measure it, then it will change and be more uncertain !!
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but I'm bored and unnecessarily responding to threads.
Pete
I assume if we try to measure it, then it will change and be more uncertain !!/
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but I'm bored and unnecessarily responding to threads.
Pete
that's what I said earlier !! . . . . . but given the coil must have a finite reactance, when the driver pack switches the voltage off (instantly) and the current decays, there must be some residual voltage across the coil.
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but I'm bored and unnecessarily responding to threads.
Pete
Sorry missed that, but the decay in current gives a soft drop. That is the point i was trying to make.
frog hopper
Well-Known Member
Skillful bit of driving to avoid that flatbed someone left in the way.
Datatek
Well-Known Member
With 500gms spring load on the armature it is impossible to do a soft drop without some very sophisticated logic which is not present in the driver pack, after the 60 milli second 12 volt pick pulse, the voltage pulses but at 12 volts with an even mark to space ratio, the voltage cut off is instantaneous for all practical purposes as I showed on the test bench and which confirmed the stylised wave forms that Land Rover provide.
I have dismantled a driver pack, I had intended to make a replacement. Two things put me off, potential copyright issues if I did a copy, and liability issues if I produced a new design. In the end I found the driver pack is easy enough to repair so I have left it at that.
Attachments
I wouldn't know where to start with that piece!!
Datatek
Well-Known Member
I might not know much about mechanics, but electronics was my bread and butter.I wouldn't know where to start with that piece!!
Datatek
Well-Known Member
The slope on the current waveform is due to back EMF from the rapidly descending armature.
I do envy bids with electronic skills. The amount of electronic things that could have been saved if I'd of known how to repair them... Apart from washing machine brushesI might not know much about mechanics, but electronics was my bread and butter.
Is this startrek talk?
We will have to agree to disagree, i know electronics is your thing, but i would read it as residual current decaying in the coil and dropping the solenoid comparatively slowly.
Datatek
Well-Known Member
When you de energise an inductor, the collapsing field creates back EMF and the polarity is the opposite of the supply voltage, this absorbed by a suppression circuit. Nothing will make a solenoid armature with a half kilo spring pressure behind it drop slowly, indeed it is important that the spring pressure is sufficient to overcome the air pressure differential in all shock load conditions and keep the valve closed.We will have to agree to disagree, i know electronics is your thing, but i would read it as residual current decaying in the coil and dropping the solenoid comparatively slowly.
You may have got the soft drop idea from the Land Rover stylised wave forms with are a bit different from reality, but even they show that there is a only a 10 micro second delay from the ECU output switching off to voltage being removed from the solenoid and less than 10 milli seconds later there is no current flow of any form. 10 milli seconds is pretty darn quick in mechanical terms.
The real wave forms are a bit different, it is not possible to produce a square voltage waveform from a transistor into an inductor, the actual wave form is a good deal more messy.
frog hopper
Well-Known Member
Fair play to you guys, I sometimes struggle to understand French, I have no chance whatever with electroneese. Respect, each to their own and all that.
I'll never look at a light switch the same again...
ned_
Active Member
I have not run away screaming yet, thanks for the award. There is still time though. I completed my rust repairs . It took a long time and was involved. Here is the story in pictures.
someday all of this will be clean. I'm eyeing the axles. This a pretty car.
masking tape applied freehand to make stencil
This is where I flooded the cavitys with Aquasteel, blocking up the holes as i spotted them so it filled to the top.
Turns out, Not good enough! Someone plainly stated on another forum that the surface needs to be scratched, and he is right. But I tried, I had to do something, I'm satisfied and will see how I get on.
Plugged the radiator in and placed it underneath the area. The cardboard is an attempt to localise the heat from the radiator.
And that's it. I have to put the radiator back on now and I don't want to. I have some issue with it. But anyway I will make myself.
someday all of this will be clean. I'm eyeing the axles. This a pretty car.
masking tape applied freehand to make stencil
This is where I flooded the cavitys with Aquasteel, blocking up the holes as i spotted them so it filled to the top.
Turns out, Not good enough! Someone plainly stated on another forum that the surface needs to be scratched, and he is right. But I tried, I had to do something, I'm satisfied and will see how I get on.
Plugged the radiator in and placed it underneath the area. The cardboard is an attempt to localise the heat from the radiator.
And that's it. I have to put the radiator back on now and I don't want to. I have some issue with it. But anyway I will make myself.
Wow, admirable..
