DC SSR switching speed

Discussion in 'General Electronics Chat' started by Art, Mar 29, 2016.

  1. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    Hi guys :)
    I have one of the DC Solid state relays coming from eBay.
    Does anyone know if they could be expected to keep up with the speed
    of some half wave rectified audio?
    Or perhaps PWM audio generated with a micro?
    Cheers, Art.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    Depends upon the SSR design.
    Most are not that fast, but some are designed for higher frequencies.
    The only way to know (if there are no specs on that) is to test it.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    How fast do you require the switching rate?
    Is this a AC output version or DC?
    If coming from China specs could be anybody's guess.
    Max.
     
  4. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    HI :) Sorry I didn’t post back. I did see this on my phone,
    Without a datasheet or the device in my hand yet, nothing can be told.

    To be honest I don’t know if direct eBay links are allowed on the forum, so hosted a pic myself:
    [​IMG]

    It is China stuff, actually supposed to be DC 25A. It least works so far driving it with a 555 at visible frequencies,
    and I can test audio with the same oscillator tomorrow.
    If I understand correctly, there could be a reduction in the frequency they can operate, when they are switching higher current
    in application, than in the testing, but Ideally I would like it to get up to audio frequencies into the kHz.

    I don’t know if this is a nasty thing to do to it, but it works when you connect the
    negatives of the control and switch sides of the relay together (which aren’t normally
    continuous),
    then you can use the supply of the load on the switch side of the relay to apply through a resistor
    to the control side of the relay, so you can turn it into a 3 pin device,
    and put it inline with a DC load.
     
    Last edited: Apr 9, 2016
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    2,373
    Also do you need that kind of power?
    There are many smaller/cheaper N.A. sources that have the internal spec's/diagrams included.
    Max.
     
  6. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    bertus likes this.
  7. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Ok, I will bear that in mind from now on. Yes I could delete Photobucket files and the pics would disappear.

    Max, I only need 3 or 4 Amps up to 30 Volts DC, I just figured I’d get a tough one.
    There's have a second one on the way if I break this because there’s a bit I can do to it.
    The circuit has 2x555 timers so a visual frequency can be modulated at an audio frequency,
    and also a H-Bridge in case it helps to deliver a bit of current to the DC SSR control input.
    It would also be possible to either go high impedance or high current return to ground.
    The Texas Instruments H-Bridge chips conveniently provide that functionality on their pins :)

    The only reason I don’t know right now if it’s handling audio frequencies is the only high current
    load I’ve used is some incandescent bulbs that won’t show audio output well.
     
  8. #12

    Expert

    Nov 30, 2010
    16,298
    6,810
    There is another reason. Humans can't see a light turn off if it's faster than about 30 Hz.
     
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