Recent Blogs Posts

  1. First attempt of TD Class on Leco Amplifier Module

    Quote Originally Posted by fitzroy View Post
    Quote Originally Posted by fitzroy View Post
    add 39k resistor from pin 1 to pin 3 of negative pwmpatd circuit i posted
    Click image for larger version. 

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ID:	6914 negative pwm circuit
  2. Current transformer calculation

    To determine how to calculate the number of turns according to the current handling for a SMPS.

    1) Determine the voltage needed for sensing and add 1 diode forward voltage in a centre tapped configuration, or 2 diode
    forward voltage drop for a single secondary winding with a bridge rectifier.

    2) Calculate the peak current for the SMPS in the primary winding.
    3) Determine the turns ratio for the current transformer. Please note that the ...
  3. Identifying fake fets and genuine ones

    Here is a short video that describe how to identify fake mosfets with genuine ones.
    Recently I was experimenting with a SMPS and decided to buy some cheap fets from the internet. I do not remember exactly if it was from E-Bay or Aliexpress but however when I tried these IRF740 they where giving up at around 1/3 of the specified load they should handle.

    The video link shows a simple test that I made and shows what to look for.
  4. Calculation of snubber components and driver gate resistors

    Dear members I am presenting an Two articles regarding the calculation of snubber components and gate drive resistors.
    It often comes the need to determine the snubber components in a half or full bridge smps. The snubber described here is intended to be put across the primary winding of a switching transformer, however if ringing is present due to factors like leakage inductance present in switching transformers we need to suppress them. In the previous article presented the text moved ...
  5. How to calculate snubber components for half and full bridge smps


    1) Put your oscilloscope probe across the LOW SIDE fet (Drain source) or BJT (collector emitter) be sure to put the ground lead
    to the negative side of the bulk caps (source of mosfet) (Emmiter of BJT).
    2) Isolate your power supply if it is an off line one to be tested with an isolating transformer otherwise there is a good chance of
    burning your oscilloscope and your smps.
    3) Depending ...
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