Electronics > Beginners
Oscilloscope pick up noise from power line
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chancs:
When I turn on the LED overhead light, my oscilloscope picks up the switching noise (they are only the same power outlet). I tried to reallocate the LED light to a different outlet, the switching noise is reduced by 50%, still noticeable. Below are some screen captures showing the waveform when the LED light is turned on and is turned off.
LED OFF
LED ON
Is there any product on the market that can reduce the switching noise?
Ian.M:
Yep. Incandescent, or line frequency magnetic ballast fluorescent lighting! >:D
For low voltage lighting, avoid SMPSUs and PWM dimming. 'Dumb' LED strips on a linear PSU are acceptable.
chancs:
So I should better off replay the LED light with traditional filament light? Is there any energy efficient light source that would interfere with my scope?
ferdieCX:
I had the same problem 5 years ago, the power brick of the LED bar interfered with the trigger of my scope.
My LED bar (Diodor brand) is specified to work between 10 to 14 V so, I made a simple power supply with a 9 V + 9 V transformer, two diodes
and a filter capacitor calculated to have less than 1 Vpp ripple. This way, the bar gets a voltage that roughly varies between 11 and 12 V.
There is also a thread about this problem:
https://www.eevblog.com/forum/beginners/oscilloscope-interference/?topicseen
JustMeHere:
https://youtu.be/ty_sxMxUWeU
Dave did a video on this
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