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G8MNY > TECH 16.07.03 00:35l 29 Lines 966 Bytes #999 (0) @ WW
BID : 5756_GB7CIP
Read: DB0FHN GUEST OE7FMI
Subj: Variable Zener
Path: DB0FHN<DB0RGB<OK0PPL<RZ6HXA<HA3PG<IK1ZNW<GB7CRV<GB7CIP
Sent: 030715/0710Z @:GB7CIP.#32.GBR.EU #:5756 [Caterham] $:5756_GB7CIP
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 but around 1/2 the voltage wnated may be optimum. Both
of the transistors are NPN. Set the voltage pot sets the Zener from 1V higher
than the zener to many times the zener. TR2 can be omitted in low current
circuits.
/QSL
73 De John, G8MNY @ GB7CIP
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