R:190704/0618Z
19628@OK2PEN.SP.BRA.SOAM [Sao Jose dos Campos] $:11161_GB7CIP R:190704/0611Z @:GB7CIP.#32.GBR.EURO #:11161 [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 ±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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