Re: Power Supply Negative/Positive

From: Ban (bansuri_at_web.de)
Date: 07/12/04 

Date: Mon, 12 Jul 2004 16:49:16 GMT

joeyla wrote:
> Hi there. I'm pretty new to electronics and have question.
>
> I have a project using Analog switches and I need +5v and -5v.
>
> I have tried using ICL7660, but I need to supply over 100mA to both
> supplies and this device does not work. I tried using a potential
> divider and a 7805 and 7905 tapping the center as ground,with no
> success either.
>
> How can I get +5 and -5 volts to my circuit without 2 power supplies??
>
> Thanks in advance,
> joeyla

Here is a small schematic for a transformer without center tab. The current
capability is around 150mA per side. View\fixed font

                             ____
                            | |
                  +-----+---|7805|---+----------------o
                  | | |____| | +5V
           1N4001 - | | |
      63mA ^ | + | ---
      ____ | ### | ---
   o-|_--_|-. ,---+ --- | |220n
            )|( | |1000u|16V |
  120Vac )|( | | | |
   o--------' '---)-----+-----+------+------+---------o
         8V/500mA | | + | | 220n GND
                  - ### | ---
           1N4001 ^ --- _|__ ---
                  | |1000u/16V | | |
                  +-----+----------|7905|---+---------o
                                   |____| -5V
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de 

-- 
ciao Ban
Bordighera, Italy

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