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flyingbrick

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Spinning a magnet across the pickup circuit is probably introducing stray currents. You could use an opto isolator to protect your arduino but really you want to shield the supporting circuitry of those hall sensors.

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Where are your 18V spikes? oin the power supply or the input pin for the micro?

I would do this;

a) create a good power supply with some decent input caps, a diode and a zener to try smooth out some real nasties... This has a lot of 4.7uF because thats on the bigger end of surface mount... just use some big through hole 10uF or 22uF even...

image.png.b1ead5a24ca4e4e9b1e5ddd4376b511e.png

 

Then do some input protection on all of your pins that connect to car stuff. This is for ADC inputs from 0-5V that need a pullup, like IAT and coolant sensors etc

image.png.5547adc8f8120faf4dd91cfbdee46b1b.png

 

For a hall effect, i would use this

image.png.a7f82835e72c65fcfaf47469f5d4f24a.png

 

and for VR, you will need to get a MAX9926 like this (they have modules)

image.png.0ed589866e6c0bd506a5af7e09858320.png

 

To drive the coils, this is a pretty decent chip i've used in the past. Oviously the 0R to the 2 supplies is so you can pick, only connect one of those :) and pick the driver you want with either inverting or non inverting outputs

image.png.eae251a3e5feacc74ef95ca850826b95.png

 

All of this came from an ECU i designed and built, but never got running!! so none is tested properly, but it is all based heavily on speeduino, FreeEMS and MicroSquirt etc (they are all 90% the same anyway) 

so should be a good starting point for (semi) reliable electronics that run in cars

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Also, draw a pic of out where your grounds actually are. You've only got to get to -0.7V before things go really weird.

 

And more also:

image.png.2edd15065d5a30c3d4cb8d9c903fd01c.png 

Are you getting V(d) excursions capacitively coupled back into V(g), or via ground-bounce?

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9 hours ago, Ned said:

Where are your 18V spikes? oin the power supply or the input pin for the micro?

 

At the arduino battery.
The pins get higher voltage spikes...

I'm going to sound like an idiot but everyone thinks i am one already, so who cares.
Those are some impressive diagrams but i don't understand any except the voltage regulator looking thing.  I wonder if i can use one of those AMS1117-5.0
The rest i have am not sure what i'm looking at or how it'd be connected.
 

8 hours ago, h4nd said:

Also, draw a pic of out where your grounds actually are. You've only got to get to -0.7V before things go really weird.

 

And more also:

image.png.2edd15065d5a30c3d4cb8d9c903fd01c.png 

Are you getting V(d) excursions capacitively coupled back into V(g), or via ground-bounce?

If i had been allowed to do more than basic electronics i'd probably know the answer to that ground bounce question.
Also i noticed there is an error in that crude drawing.
That diode connected to the "Arduino ground" actually bridges the output and power supply pins on that same transistor.

And that diode you put an arrow to, without that the mostfet sometimes started making horrible noises until i added that.

 

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ST has a great application note (AN2689) about protecting electronic circuits in automotive environments, well worth a read (I skip over the maths and look at the pretty pictures):

https://www.st.com/content/ccc/resource/technical/document/application_note/1f/d7/fc/6d/2e/27/48/98/CD00181783.pdf/files/CD00181783.pdf/jcr:content/translations/en.CD00181783.pdf

 

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somewhat related to this thread, I have 3 electrical components I need to solder together and fit into my motorbike. The area they are going is not guaranteed to be water proof and there will be lots of vibration. What are some tips for keeping everything alive and working? silicone over bear metal connections, or heatshrink? can I silicone the bridge rectifier to the capacitor? I think everything is oversized and wont spend its whole life at peak temperature. There isnt enough room to put them in a watertight box

IMG_1733.JPEG

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That's some good hints but i find it works if i use a different code library in the nano.  Go figure.

With regards to the bike parts.  I'd go heat shrink and something like waxoil over the top, so you can remove it if you have to.  Silicon is a one time thing.
I've used wax but i don't think wax would like the wet heat-cold bike environment much.

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9 hours ago, peteretep said:

 

Becuase I don’t know any better and am just following this YouTube video

 

 

i told you to throw that diode in the bin Peter... you better not put that in...

you could solder wires with glue lined heat shrink to the cap, cable tie them to the cab as strain relief. Then crimp spade terminals to the wires to go to the bridge rectifier? Bolt the bridge rectifier to something metal as a heat sink? A bit of water will be fine, as long as it's not submerged. You could put some dielectric grease on the connections if you're worried about water

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