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PWM shielding

Discussion in 'General Electronics Discussion' started by Aniketbarapatre26, Jan 5, 2022.

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  1. Aniketbarapatre26

    Aniketbarapatre26

    1
    0
    Jan 5, 2022
    Hello,
    I am using shielded wires for pwm signals which are comparatively heavy than normal hook-up wires. In this, the wires are not shielded for a length of around 50-70mm as i have to solder it to the connector. Will it create any issue.
    Can i use shielding over the normal hook-up wires instead of shielded wire.
     
  2. crutschow

    crutschow

    336
    117
    May 7, 2021
    Depends upon the level of shielding you need.
    What "issue" are you concerned about?
     
  3. Nanren888

    Nanren888

    602
    184
    Nov 8, 2015
    Frequency? Voltage? Current? Distance to possibly affected circuits? What is being shielded from it?
    In short
     
  4. Fish4Fun

    Fish4Fun So long, and Thanks for all the Fish!

    471
    109
    Aug 27, 2013
    @Aniketbarapatre26,

    Welcome to Electronics Point!

    PWM (Pulse Width Modulation) is generally a reference to a type of "output" while "signals" is generally a reference to some type of communication protocol.

    A PWM output is generally a "conceptual equivalent" to a rheostat ... ie a PWM output can be used as a light dimmer, a speed control, a volume control, etc, etc. In the case of SMPS (Switch Mode Power Supplies) ... PWM can be used to control OR regulate: Output Voltage, Output Current, Output Power.

    In motion control PWM can be used to regulate speed, torque, acceleration/deceleration, etc, etc ...

    In all of the cases mentioned so far, there is no way to suggest any handling precautions associate with how a PWM output is wired because there is no information implicitly implied by the term "PWM Signals".

    If, by "PWM signals", you are referring to the output from some Digital Source to some type of amplifier, then you are going to have to provide a considerable amount of information before any advice can be offered.

    BUT ....

    As a general rule, the higher the frequency, and the higher the current, the more problematic distance between the signal source and the output amplifier become.

    For instance:

    If your amplifier is a simple MOSFET like an FDS6672A (30V N-Channel Mosfet with a Typical Gate Threshold of 1.2V) and your PWM output from your digital source to the FDS6672A Gate is +5V/0V with a PWM Frequency of 200hz and duty cycle is 20% to 80% .... chances are you could use 100ft of off-the-shelf speaker wire with little or no problems.

    If you are trying to drive something like an IRFP260 with +15V/0V at 200khz with a duty cycle of 10% to 90% and you are trying to prevent RF interference with other equipment within a few hundred yards I would suggest you place your shielded cable inside metal conduit and hope for the best.

    If your Amplifier has some type of digital or analog "pre-amplifier" then you might need to consider some type of line attenuation // frequency filtering .... or perhaps even use like the RS485 impedance balanced pair protocol ( https://e2e.ti.com/blogs_/b/analogw...nation-is-necessary-and-how-to-do-it-properly ).

    Doubt any of this will help, but given the lack of information in your post, it is the best I can do.

    Cheers!

    Fish
     
    Harald Kapp likes this.
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