Anything not specifically related to the Speeduino hardware. Eg sensors, bluetooth, displays etc
By theonewithin
#55168
Really need a tooth log or output from the VR condition with the VR sensor input over the top.

Just the VR sensor along tells very little.

Also please be VERY specific about your setup.

What board. What VR conditioner. How are you powering everything. What sensor. etc etc.

Detailed info on your setup to help ensure nothing in that is actually causing you issues.
By sevtix
#55174
Thanks so much guys for the tip!

I bought the registered version and looked at the tooth log!

the thing is that i don't have an official speeduino but designed my own based on the no2c.
the 15-12V -> 5V buck converter has created the noise :evil: .
direct PC 5V works perfectly (with and without vr sensor resistor)

my 50cc is idling and revving pretty good on 5v usb!
thanks again!

which voltage regulator ic is used on the speeduino / no2c?
I will use the same one!

tooth log (12V - 5V converter):
Image

tooth log (direct 5v over usb):
Image
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By PSIG
#55175
sevtix wrote: Sat Feb 05, 2022 4:20 pmthe thing is that i don't have an official speeduino but designed my own based on the no2c.
the 15-12V -> 5V buck converter has created the noise :evil: .
Thank you for the follow-up of your situation. This will help others looking for help on similar situations in the future. It may also help to add a link to your final post, into the top of your first post, for others to find your solutions easier. ;)
sevtix wrote: Fri Feb 04, 2022 8:22 pm1. I hooked up my VR sensor with and without the resistor in between. Without software filtering its still unusable and in idle the rpm goes from the correct rpm to random 10k rpm and everything between.
2. I measured the output of the VR conditioner board and found out that the conditioner works perfectly (with the vr sensor resistor a little bit better)
Fabulous! I hope you can see why I said and asked what I did. Indeed the assumption that there was a wheel or sensor or signal conditioner module issue was understandable, but false. You took the time and effort to prove they all are working well.

It is also the reason I did not suggest a generic "fix", such as a shunt resistor. As you found, a shunt only reduces the amplitude of whatever quality signal you have. Like turning-down the volume. It does not change a signal-to-noise ratio. Like a poor radio station, turning-down the volume does not fix the signal, but only makes it a quieter but still noisy station. Shunt resistors have uses, but not for this situation.

I'm glad you found and are fixing your noise source, and can now continue on your journey! Image
By theonewithin
#55180
You can check the BOM of the NO2C to see what it uses.

The majority of Speeduino boards use old school linear voltage regulators.

Not super efficient but have a good output.
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By PSIG
#55181
+1, and I have used buck converters not for efficiency, but to reduce heat within the ECM case (search threads for Murata or buck). While a buck typically needs 3 to 5 inductors and capacitors to smooth the noise, I simply added the basic buck before a typical linear regulator to smooth it.

The goal was simply to reduce the work the LM was doing from typical ±14V down to 5V (they get quite hot doing "nothing"), to something closer to 7 or 8V input to the LM for much lower heat production. If using a buck for input regulation, articles such as this from Maxim may be helpful.
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By DStage
#55240
PSIG wrote: Sun Feb 06, 2022 4:35 pm I simply added the basic buck before a typical linear regulator to smooth it.
The goal was simply to reduce the work the LM was doing from typical ±14V down to 5V (they get quite hot doing "nothing"), to something closer to 7 or 8V input to the LM for much lower heat production.
Yep, that's a useful technique that let's to get something good from both words - higher efficiency of SMPS and low noise of a linear regulator.

However, in this case I kind of doubt that the noise from DCDC converter was directly influencing the VR path. The crank trigger signal spectrum reaches 1kHz at max as it's close to a sine wave (very little harmonics) and even with 60-1 at 12000 RPM the base frequency is only 200Hz. On the other hand the ripple noise of DCDC converter is way above acoustic range, usually something between 200kHz to 1MHz of switching frequency and higher harmonics. I don't think there are any significant intermodulations that could create low frequency noise. I don't know how DSC is build but I'm guessing it has at least half decent PSRR and low pass filter at the input.
My bet in this case would be messing up something in the MCU itself, perhaps due to a combination of shitty filtering of DCDC output and its load sensitivity with AVR internal clock. Or I just have vivid imagination :lol:
By NickZ
#55402
good old buck converter, I did the same with my first designs. I did fix it be putting a huge cap on the 5v output of the buck.

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