Mensaje originado el: 31/12/10 a las: 22:50 z

Variable Zener




From: G8MNY@GB7CIP.#32.GBR.EU
To  : TECH@WW

By G8MNY
When you can't find a zener of the right voltage try this circuit:-

    Zener +   -----------------------------
    6-60v          !       !          !
                   !      c \!       POT
                   !   TR1   !------>100K
                   !      e /!        !
                   !      !           !
                   !     ---\         !
                   !     / \          !
                   !     --- 5v       !
                   c\!    !           !
                TR2  !----            !
                   e/!                !
                   !                  !
   Zener -   ---------------------------

The Zener can be 5-10V. Both transistors are NPN. Set the voltage pot sets the
Zener from 1V higher than the zener to many times the zener.
TR2 can omitted in some low current circuits.

73 De John, G8MNY @ GB7CIP