G8MNY  > TECH     31.05.25 09:00z 38 Lines 1203 Bytes #90 (0) @ WW
BID : 33849_GB7CIP
Read: GUEST
Subj: Splitting a floating PSU
Path: ED1ZAC<ED1ZAC<GB7CIP
Sent: 250531/0845Z @:GB7CIP.#32.GBR.EURO #:33849 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                          (New Aug 06)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

Here is a simple way to spit a single floating power supply into +/- rails. It
can be for any voltage 6V-100V to give ñ3V to ñ50V.

      ÚÄÄÄÄÄÄÄÄ¿ +
      ³        ÃÄÄÄÄÂÄÄÄÄÂÄÄÄ>+ve
      ³Floating³   1K  ³/ 
      ³        ³    ÃÄÄ´NPN
      ³ Power  ³   _³_ ³\e  
      ³        ³ D1\_/   ÃÄÄÄ>0V
      ³ Supply ³    ³  ³/e
      ³        ³    ÃÄÄ´PNP
      ³        ³   1K  ³\
      ³        ÃÄÄÄÄÁÄÄÄÄÁÄÄÄ>-ve
      ÀÄÄÄÄÄÄÄÄÙ -

The asymmetrical currents & voltages will affect the components needed (e.g.
transistors have to handle peak offset current & heat), in some applications,
e.g. value of 1K R may be 39K on 100V. Higher currents may need darlingtons or
P & N ch MOSFETs.

The above circuit should provide adequate balance for testing most things that
need a balanced supply.

D1 provides some cross over bias keeping the transistors in class B, 2 diodes
in series may do better, but easy to get into class AB/A & get hot when this is
not needed!


Y Don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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