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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Jeez, Thorsten............... posted by PhilH on November 23, 2001 at 05:54:38:
Hi,> Maybe I missed something about your implementation of the 431.
> How are you deriving the 6 or 10 volts for the common-base (or
> gate) transistor?Resistive Divider.
So, for around 100V:
collector of MJE340 is "cacoded zenner" Anode
From there one 100k resistor goes to the base of the MJE340, a 5k6 resistor to ground. Emitter of MJE340 connects to 431 Anode.
Another 39k resistor from the MJE 340 collector forms the upper part of the voltage divider for the 431 Voltage Setting. The lower resistor is 1k, giving pretty exactly 100V. Between this voltage divider and the "adj" pin of the 431 a 10k resistor is inserted to protect the 431. The 100k resistor is bypassed with around 22uF capacitance if low dynamic output impedance is desired.
The cathode of of the 431 goes to ground.
All the transistor does is take the brunt of the Voltage Drop and thus the dissipation, the dynamic and static behaviour of the regulator is still pure 431....
As said, the upper cascode unit can be anything, FET, BJT or Valve.... Simply adjust the voltage dividers to suit.
Ciao T
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Follow Ups
- Re: Jeez, Thorsten............... - Thorsten 06:30:43 11/23/01 (1)
- My brain's awake now - PhilH 07:12:36 11/23/01 (0)
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