1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

ZFF Self-Modulating PWM

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by skeeterb, May 9, 2008.

  1. Ubergeek63

    Ubergeek63 Well-Known Member

    Joined:
    Apr 16, 2008
    Messages:
    1,886
    Likes:
    37
    You do not adjust the PWM, the 9910 adjusts in order to regulate the current.

    You can put in a voltage on the LD (linear dimming- it is meant to drive power LEDs) pin to bring the peak voltage on the current sense down from 0.25V.

    When the frequency adjust resistor is tied to the drive pin instead of ground it works in constant off time mode. In this mode the frequency varies as the line and load vary to maintain a constant current output.
     
  2. skeeterb

    skeeterb Member

    Joined:
    Apr 7, 2007
    Messages:
    214
    Likes:
    0
    Location:
    USA
    That circuit is a whole lot simpler than most PWMs that are found out there on the net. I may use that if I do build my Hydrogen on Demand system eventually.
     
  3. skeeterb

    skeeterb Member

    Joined:
    Apr 7, 2007
    Messages:
    214
    Likes:
    0
    Location:
    USA
    Using the previously attached Schematic, what could be used to control the duty cycle of that circuit, w/o using a PIC Microcontroller?
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Ubergeek63

    Ubergeek63 Well-Known Member

    Joined:
    Apr 16, 2008
    Messages:
    1,886
    Likes:
    37

    Are you asking about the 555 circuit or the HV9910?
     
    Last edited: May 17, 2008

Share This Page