Thanks for the responses. Of course and it is overkill - my appliance will be a power supply, housing 12 regulators. 🙄
Then, I will just screw the chassis using 8 points. I will just pay some more for extra bending, but I would eventually pay more too, should I use gaskets.
Then, how much worse would my dirty-box solution be compared to a Schaffner IEC filtered inlet, should I use no gaskets for the box? 😕 As I described it in the first place, actually.
EDIT: My original plan involved screwing a Hammond 1590T against the rear vertical wall, just by drilling 4 holes on this wall and inserting the screws through them to tighten up into the existing threads of the 1590T. Lid goes unused.
Maximum aperture length then should be around 12cm, since this is the maximum dimension of the little box. Can this be considered adequate?
Then, I will just screw the chassis using 8 points. I will just pay some more for extra bending, but I would eventually pay more too, should I use gaskets.
Then, how much worse would my dirty-box solution be compared to a Schaffner IEC filtered inlet, should I use no gaskets for the box? 😕 As I described it in the first place, actually.
EDIT: My original plan involved screwing a Hammond 1590T against the rear vertical wall, just by drilling 4 holes on this wall and inserting the screws through them to tighten up into the existing threads of the 1590T. Lid goes unused.
Maximum aperture length then should be around 12cm, since this is the maximum dimension of the little box. Can this be considered adequate?
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12cm is a 1/4 wavelength at ~600Mhz, where it becomes an efficient slot radiator, so if you are only looking to attenuate AM radio and FM radio that will do fine, if you are trying to keep the cell phones out you will need to do much better.
What is the actual noise RF limit you are trying to meet (As low as possible is not an answer)?
This question should really be the one driving the design of the EMC measures.
73 Dan.
What is the actual noise RF limit you are trying to meet (As low as possible is not an answer)?
This question should really be the one driving the design of the EMC measures.
73 Dan.
Nonsense. Well designed power amp must be tolerant to any of power supply noise or pollution. Well designed power amp works in a way its feedback`s elements are calculated:
Power supply rejection ratio - Wikipedia, the free encyclopedia
Power supply rejection ratio - Wikipedia, the free encyclopedia
Yeah, "it should still work inside a microwave oven" isn't really relevant...
I'd use as a criterion : it should not show a measurable difference between a clean EMI environment and my living room. Especially I don't want to hear "meep-meep-meep" every time the cellphone chats with its masters (this isn't so easy).
As I said, the application is a power supply that incorporates 12 regulators. Loads will be guitar effect stompboxes, which will in turn feed a guitar amplifier.
Most guitar amplifiers are horrible at maintaining adequate shielding above a few MHz (this is something I assume based on their chassis layouts, many of them being just an aluminum pi), so I assume I shouldn't have any issues at all.
Do you think I must go up to GHz? Eventually this would mean just stacking some gaskets to reduce maximum aperture dimensions down to the diameter of the holes needed to mount jacks etc, based on the information on this thread. But I believe I have the ability to decide after I assemble my power supply, to see whether I encounter any issues without them. 🙄
EDIT: I run a solid state guitar amp in my bedroom with no issues at all. Chassis is just a pi piece of steel. Since I will run my equipment in my living room, my bedroom and in live gigs, I don't think I need to compare the functionality to an EMI-free environment. 😛
Most guitar amplifiers are horrible at maintaining adequate shielding above a few MHz (this is something I assume based on their chassis layouts, many of them being just an aluminum pi), so I assume I shouldn't have any issues at all.
Do you think I must go up to GHz? Eventually this would mean just stacking some gaskets to reduce maximum aperture dimensions down to the diameter of the holes needed to mount jacks etc, based on the information on this thread. But I believe I have the ability to decide after I assemble my power supply, to see whether I encounter any issues without them. 🙄
EDIT: I run a solid state guitar amp in my bedroom with no issues at all. Chassis is just a pi piece of steel. Since I will run my equipment in my living room, my bedroom and in live gigs, I don't think I need to compare the functionality to an EMI-free environment. 😛
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Can you describe an example where you had such annoying issues? I would like to know! (I am not being ironic)
For example the old Technics amp that powers the speakers on my desk... it comes from before the wireless era, so :
Cell phone interference sound effect - YouTube
If it is just a power supply, it would be better to ensure the stompboxes themselves have adequate filtering on the power input (ie, ferrite bead, and a cap...) since that would also remove hash picked by the cable...
Cell phone interference sound effect - YouTube
If it is just a power supply, it would be better to ensure the stompboxes themselves have adequate filtering on the power input (ie, ferrite bead, and a cap...) since that would also remove hash picked by the cable...
Oh, that noise. I always get it when I send a message via my cell-phone on my computer desk! And have always known what it is. 🙂
Of course and I will provide local decoupling/filtering for my pedals. And since I use uncompensated NE5534's for the regulators, I would rather ensure that nothing up to 100 MHz gets inside. It is merely theoretical that UGBW could reach that much (Spice simulations) for the open loop of my circuit, but anyway it is good practice to ensure that nothing gets inside and flirts with instability issues. 🙄
Of course and I will provide local decoupling/filtering for my pedals. And since I use uncompensated NE5534's for the regulators, I would rather ensure that nothing up to 100 MHz gets inside. It is merely theoretical that UGBW could reach that much (Spice simulations) for the open loop of my circuit, but anyway it is good practice to ensure that nothing gets inside and flirts with instability issues. 🙄
We used two separate inductors but there is no reason why you cant use a common mode choke.
What about the following implementation?
Painting one of the two metals that make contact with a thin layer of conductive paint - not around the screw joint territory, so that when the metals are screwed together, the paint layer will be forced to touch the other metal.
I think this is a sensible solution - but I don't know anything about conductive paint properties - for example, will it eventualy corrode? I find it a quite cheap and easy solution to implement, if it is going to be better than using nothing. That's where I am asking for your input! 🙂
Painting one of the two metals that make contact with a thin layer of conductive paint - not around the screw joint territory, so that when the metals are screwed together, the paint layer will be forced to touch the other metal.
I think this is a sensible solution - but I don't know anything about conductive paint properties - for example, will it eventualy corrode? I find it a quite cheap and easy solution to implement, if it is going to be better than using nothing. That's where I am asking for your input! 🙂
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