Presumably you are using a relay with a low voltage coil. Why not ease the
low voltage current requirements by using a relay with a high voltage AC
coil.

If my presumption is correct then you will probably reduce your current
consumption on the 5 volt rail to 45mA or less. Use a small Triac or
thyristor to switch the relay.

Regards

Chris Carr

 > -----Original Message-----
> From: Alexandre Domingos F. Souza [mailto:taito@TERRA.COM.BR]
> Sent: Thursday, 26 July 2001 10:53
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Transformerless PSU
>
>
>         Dear guys,
>
>         I think it's a basic one, but maybe fits the list
>
>         I designed a circuit with a PIC (12C508) that turns on and off a
> relay, controlled by an external source. The power to this circuit (around
> 120mA) is a small transformer. I'd like to build a transformerless PSU
into
> this circuit. But EVERY scheme I found on the internet was unusable. I saw
> something on the Embeeded Control Handbook from Microchip, but it only
goes
> to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or
at
> least learn to) a simple transformerless PSU that can give me 12vcc / 120
> mA???
>
>         Thanks for any info! :o)
>
>
> ---8<---Corte aqui---8<----
>
> Alexandre Souza
> taito@terra.com.br
> http://planeta.terra.com.br/lazer/pinball/
>
> ---8<---Corte aqui---8<----
>
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