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Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt


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8 hours ago, ajg193 said:

Woo the LPG Corolla now has a working fuel gauge.

 

I jerry rigged an arduino nano with a linear hall effect sensor (sensing the magnetic float gauge on the tank) and a mosfet to drive the gauge. It's mega whorey though as all my electrical tools are up in Auckland and I'm taking power from the rear defogger to power the nano. And all of the wires are just out of a stripped extension lead so have mains AC colouring.

 

I gave it a rough calibration by just moving the sensor around  to get approximate levels (2/3 full tank), then went and filled the car up and the gauge dropped straight to empty - the analogWrite value went over 255 and looped back to zero. A quick fix in the code to limit the output to 255 and it was away laughing. Now to drive the car until the tank is almost empty and confirm the calibration at the lower end / I'm not sure if the gauge response is even linear.

 

 

 

how is the sensor arranged with the magnetic float? I can only imagine a toothed wheel going past the sensor

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11 hours ago, peteretep said:

 

how is the sensor arranged with the magnetic float? I can only imagine a toothed wheel going past the sensor

 

 

There is some sort of float mechanism within the tank and a little circular magnet with a needle that you stick onto the tank that rotates to show how full the tank is. The hall effect sensor picks up the magnetic field (which changes as the magnet rotates towards and away from the sensor) and outputs a voltage that depends on the strength and polarity of the magnetic field.

 

This kind of explains it:

sensorspecsheet.png

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Question for the professional automotive repair techs,

When fitting a new starter (like a brand new unit) is it correct practice to apply any lube to.the starter pinion?

I wouldn't want to risk contamination of the clutch. But should something be applied?

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27 minutes ago, RUNAMUCK said:

Question for the professional automotive repair techs,

When fitting a new starter (like a brand new unit) is it correct practice to apply any lube to.the starter pinion?

I wouldn't want to risk contamination of the clutch. But should something be applied?

Just chuck it in dry. Should all be good to go out of the box. I only lubed stuff when reconditioning them 

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  • 2 weeks later...

Diodes.

My very very limited understanding of these is they only allow current to flow one way?

Say I have a 12v cell. And I want to keep it charged by taking a feed off a circuit. The circuit is only live sometimes. When it's not, I don't want the cell to feed power into that circuit. As it would both power it up needlessly, and further discharge the cell. Which defeats the purpose of being tee'd into it in the first place.

Would placing a diode between where it's tied into the feed and the cell allow it to take charge, but keep the energy stored in the cell to do only the job it's there for?

If so, what kind?

@h4nd, I'm quite sure this is your field of expertise? 

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On 26/06/2018 at 22:31, Willdat? said:

Spring compressors - not something I need often, but keen to own. Where's the sweet spot of cheap/not shit?

I might be a bit late, but make some at school? I can take a photo of mine if wanted. I didn't make them, but they are solid as fuuuuck. I'd trust them over the ones you buy with cast hooks.

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