The capacitor doesn't have a concept of "fast enough", it's a passive component. The signal is what determines what it does when it encounters the capacitor. Non-linearities and capacitor species aside, a good ole x7r 100nF would clean this up.
In general you can just liberally dump 100nF caps all over your pcb power traces and quash most problems like this before even knowing they exist. I joke that you make a circuit then take out your 100nF salt shaker to make it just right.
The capacitor has a self inductance. That's why you use low self inductance capacitors with very short leads or traces in this role. 100 nF ceramics are fine, but you may actually need a 100 nF and a 10 nF side-by-side because of that inductance depending on how dirty your power line is. Fast clocked circuitry can be pretty nasty.
Through hole parts cap out at maybe low MHz. Many electrolytic caps frankly cannot effectively decouple signals above 100s of kHz even. Above that value, capacitors become inductors due to lead lengths, parasitic resistance, and other details.
To make capacitors work faster, we make them smaller and smaller. Surface Mount Caps are the only way to reach 20MHz++ decoupling speeds, and you need crazier tricks if you need additional decoupling beyond that frequency.
Yes, but we are splitting hairs at that point. The transient spike is a high impedance voltage that is tripping the high impedance internal protection circuitry of the magnetometer. So whether we have 20mOhms of capacitive decoupling or 500mOhms of inductive decoupling, both are better than the infinite impedance of nothing there.
We're not building a precision filter, were cutting the paws off of a paper tiger. No need to let perfect be the enemy of good.
It's an easy test though and it can be an SMD component and some PUR-coated magnet wire or 30 awg single stranded kynar hookup wire.
Use a small amount of glue from a hot glue gun to fixate it when done, or epoxy if that's your thing. Avoid cyanoacrylate. Not always needed but I imagine a drone moves around alot.
Bodge wiring is a good skill to acquire - PCBs will not always be perfect. Maybe practice on something else first?
I have a bunch of through-hole parts for these sorts of situations. There are plenty of small through-hole ceramics that have leads if you really want to go there.
That's because you weren't dealing with 20MHz noise.
Hobbyists are not dealing with 20MHz noise issues. Period. And if you are actually crazy enough to deal with high frequency circuits like that, you would well know that the land of through hole designs is simply insufficient, and that you are probably somewhere with some 0402 capacitors and some tweezers right now.
> Hobbyists are not dealing with 20MHz noise issues.
It happens. Not often, but it does happen and it depends on the hobbyist and what they're up to (but you won't be sticking that together on a breadboard). Also: if you start using HCT, AHC or even G parts where you don't really need them it can happen to you in places where you don't normally expect it. Those things have crazy fast rise times.
Real talk: 6 layer oshpark is cheap enough for a hobbyist and there are a bunch of 500MHz / DDR2 parts that can be laid out. Like 0.8mm pitch BGAs can fit and breakout.
So yeah. Hobbyists can go here. But here be dragons!!
Nonetheless, I continue to assert that typical hobbyists are making mistakes at 100kHz region rather than the 100MHz region.
That's fair. It's just that I have seen some hobbyists doing the most insane stuff and eventually getting it to work. Some HAMs for instance have pretty extreme skills and it is not their profession, they just do it because they like it, not because they get paid.
And in many of those cases their skills are hard capped by their budget for test gear and simulation software rather than by their actual ability. Keep in mind that until not that long ago anything above 1 G was fair game because 'nobody does anything there anyway' and so HAMs and radio astronomers were pretty much the only ones with experience in that region.
If it's really 20MHz++ noise that's screwing him, you need something faster than a through hole capacitor IMO to deal with it.
That being said, I'm not 100% convinced this is a 20MHz++ noise issue.
The capacitor doesn't have a concept of "fast enough", it's a passive component. The signal is what determines what it does when it encounters the capacitor. Non-linearities and capacitor species aside, a good ole x7r 100nF would clean this up.
In general you can just liberally dump 100nF caps all over your pcb power traces and quash most problems like this before even knowing they exist. I joke that you make a circuit then take out your 100nF salt shaker to make it just right.
The capacitor has a self inductance. That's why you use low self inductance capacitors with very short leads or traces in this role. 100 nF ceramics are fine, but you may actually need a 100 nF and a 10 nF side-by-side because of that inductance depending on how dirty your power line is. Fast clocked circuitry can be pretty nasty.
Look up parasitic inductance.
Through hole parts cap out at maybe low MHz. Many electrolytic caps frankly cannot effectively decouple signals above 100s of kHz even. Above that value, capacitors become inductors due to lead lengths, parasitic resistance, and other details.
To make capacitors work faster, we make them smaller and smaller. Surface Mount Caps are the only way to reach 20MHz++ decoupling speeds, and you need crazier tricks if you need additional decoupling beyond that frequency.
Yes, but we are splitting hairs at that point. The transient spike is a high impedance voltage that is tripping the high impedance internal protection circuitry of the magnetometer. So whether we have 20mOhms of capacitive decoupling or 500mOhms of inductive decoupling, both are better than the infinite impedance of nothing there.
We're not building a precision filter, were cutting the paws off of a paper tiger. No need to let perfect be the enemy of good.
It's an easy test though and it can be an SMD component and some PUR-coated magnet wire or 30 awg single stranded kynar hookup wire.
Use a small amount of glue from a hot glue gun to fixate it when done, or epoxy if that's your thing. Avoid cyanoacrylate. Not always needed but I imagine a drone moves around alot.
Bodge wiring is a good skill to acquire - PCBs will not always be perfect. Maybe practice on something else first?
True.
I have a bunch of through-hole parts for these sorts of situations. There are plenty of small through-hole ceramics that have leads if you really want to go there.
https://www.digikey.com/en/products/detail/vishay-beyschlag-...
Like this or something similar.
I've seen piggy backed decoupling caps straddling chips on some pretty fancy hardware. This lesson is re-learned quite frequently ;)
you can dead bug SMD caps
> If it's really 20MHz++ noise that's screwing him, you need something faster than a through hole capacitor IMO to deal with it.
That's always worked well enough in the past.
That's because you weren't dealing with 20MHz noise.
Hobbyists are not dealing with 20MHz noise issues. Period. And if you are actually crazy enough to deal with high frequency circuits like that, you would well know that the land of through hole designs is simply insufficient, and that you are probably somewhere with some 0402 capacitors and some tweezers right now.
> Hobbyists are not dealing with 20MHz noise issues.
It happens. Not often, but it does happen and it depends on the hobbyist and what they're up to (but you won't be sticking that together on a breadboard). Also: if you start using HCT, AHC or even G parts where you don't really need them it can happen to you in places where you don't normally expect it. Those things have crazy fast rise times.
Real talk: 6 layer oshpark is cheap enough for a hobbyist and there are a bunch of 500MHz / DDR2 parts that can be laid out. Like 0.8mm pitch BGAs can fit and breakout.
So yeah. Hobbyists can go here. But here be dragons!!
Nonetheless, I continue to assert that typical hobbyists are making mistakes at 100kHz region rather than the 100MHz region.
That's fair. It's just that I have seen some hobbyists doing the most insane stuff and eventually getting it to work. Some HAMs for instance have pretty extreme skills and it is not their profession, they just do it because they like it, not because they get paid.
And in many of those cases their skills are hard capped by their budget for test gear and simulation software rather than by their actual ability. Keep in mind that until not that long ago anything above 1 G was fair game because 'nobody does anything there anyway' and so HAMs and radio astronomers were pretty much the only ones with experience in that region.
> That's because you weren't dealing with 20MHz noise.
That is just straight up not correct