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| Do I need shielded chokes for noise suppression |
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| Simon:
--- Quote from: T3sl4co1l on November 20, 2018, 07:53:39 am ---It's.... fans? Did you try ferrite beads on their leads? Tim --- End quote --- No I'm shoving a filter PCB right up the back of them so that the wire connector is essentially now a PCB connector so that I get some bypassing as close as possible to the power inputs to stop the supply leads radiating all over the place. |
| T3sl4co1l:
That's a good plan. :) That works best on metal shell, brushed motors (I'm a bit incredulous that a "brushless" fan can be as noisy?), but I suppose it'll still help here. But that wouldn't be with the 16A choke, would it? Or are these some big fucking fans, not just little cooling fans?! Tim |
| Simon:
The fans are small, yes they are a horrible brush-less design probably because they are so compact they hardly have room for bypass capacitors. They are so bad that with any amount of filtering starting them up at full supply voltage with no soft start means that they crowbar the power supply and drop out and then repeat, sitting there oscillating (mechanically). So now my voltage regulator has to be controlled by the µC to bring the voltage up slowly, they are a fucking pain but I have to use them. I was planning to put two of those inductors in parallel on my power input to the ECU/voltage regulator as I need 20A constant draw and then further filtering right up the back of the motors themselves. I could put those on or I could use what I already have, I need to look at specs and probably go through the Wurth website to see what they have in the 8-12A range that might be better than the TDK thing I used that has very little to say about it. The filter PCB screws to the back of the metal motor body with the screws going onto chassis ground pads on the PCB so that return to chassis is as short as possible. |
| Simon:
On the motor filter board i used these: https://product.tdk.com/info/en/catalog/datasheets/cmf_commercial_power_acm1513_en.pdf but I have no idea how to relate the impedance to the dB on the wurth part |
| coppercone2:
I have seen a choke attached to a fan in a 80s spectrum analyzer but i always thought it was brushed lol, maybe not Fans and pumps suck ass in terms of emi. Also you end up needing to design qhat i call cheap trash interface circuits. So you control the fan speed by hacking the tacho? |
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