high di/dt and dv/dt

Discussion in 'The Projects Forum' started by EECAT, May 25, 2008.

  1. EECAT

    Thread Starter New Member

    May 11, 2008
    4
    0
    I have built an LM555 timer which produces 5V output pulses at output with time period in millisec range. This 5V pulse i will be connecting to my amplifier to obtain voltage pulses of 250V as well as current pulses of 40mA. I realize that the due to millisec time period, di/dt or dv/dt will be high which might cause problems. A high di/dt might induce a back emf and damage my amplifier. Are my thoughts correct? If so, how to protect my expensive amplifier from a high di/dt or dv/dt?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    A back EMF will be produced if you have an inductive load on your amplifier. To absorb the back EMF place a diode (with high surge current) in parallel with the inductor. Connect the anode to ground and the cathode to the side of the inductor with positive voltage.
     
  3. EECAT

    Thread Starter New Member

    May 11, 2008
    4
    0
    My load is resistive but it is connected to amplifier by a large wire, which can inadvertently be wound and may be like a coil with finite inductance. Can a high di/dt or dv/dt create problems now? should i put the reverse biased diode across the coil? thanks.
     
    Last edited: May 26, 2008
  4. EECAT

    Thread Starter New Member

    May 11, 2008
    4
    0
    how does a high dv/dt impact safety considerations?
     
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