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G8MNY  > TECH     17.02.19 09:00l 38 Lines 1199 Bytes #4 (0) @ WW
BID : 59413_GB7CIP
Subj: Splitting a floating PSU
Sent: 190217/0757Z @:GB7CIP.#32.GBR.EURO #:59413 [Caterham Surrey GBR]

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 ˝3V to ˝50V.

      ┌────────┐ +
      │        ├────┬────┬───>+ve
      │Floating│   1k  │/ 
      │        │    ├──┤NPN
      │ Power  │   _│_ │\e  
      │        │ D1\_/   ├───>0V
      │ Supply │    │  │/e
      │        │    ├──┤PNP
      │        │   1k  │\
      │        ├────┴────┴───>-ve
      └────────┘ -

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 darlings 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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