Hello diyers,
Simple question, shielding the flyback transformer only on the outside with copper tape would help with radiated noise?
Should the external shield be tied to the primary ground or secondary? (I suppose primary)
Are there any negatives doing so?
Simple question, shielding the flyback transformer only on the outside with copper tape would help with radiated noise?
Should the external shield be tied to the primary ground or secondary? (I suppose primary)
Are there any negatives doing so?
If the primary winding is outside, it can help and the shield should be connected to the primary ground, but it is preferable to make the connection via a Y capacitor: for AC, it changes nothing but in case of an accidental contact with a secondary part it will not compromise the safety. A 1 to 4.7nF is suitable.
If the primary is inside, the effect of the shield will be negligible
If the primary is inside, the effect of the shield will be negligible
SMPS transformer usually have their primary and secondary interleaved, however the outer winding layer should go to the "cold" side of the primary supply while the "hot" side of the winding which is connected to the switching device causing the noise should be connected tot he inner side of the winding.
The shield will be only on the outside shell and not in between primary/secondary, it's just mainly to avoid radiated noise coupling in nearby components after filtering.
This flyback is incredibly noisy, tried some snubber on the primary but the resistor became like lava (5w res) even with a 0.01uf 400v ac rated film cap, resistor to dc_in -》cap dc_out
It's an old smps with yellow covered tape flyback
This flyback is incredibly noisy, tried some snubber on the primary but the resistor became like lava (5w res) even with a 0.01uf 400v ac rated film cap, resistor to dc_in -》cap dc_out
It's an old smps with yellow covered tape flyback
You can try to explore the space around the transformer with an oscilloscope probe as sniffer (no direct contact). If you see a significant level of the switching waveform when the tip is close to the transformer, screening might be advantageous.
You can find some remediating measures here too: https://www.diyaudio.com/community/threads/smps-killed-my-radio-reception.373045/post-6683777
You can find some remediating measures here too: https://www.diyaudio.com/community/threads/smps-killed-my-radio-reception.373045/post-6683777
The "shield" you mention is called a flux band and it needs to be connected to the utility ground or alternatively left floating like a shorted single-turn.
The Gauss band acts against magnetic leaks; it may also work as an electrostatic shield if it covers most of the transformer and is connected to the ground