5v From Serial Port

[TONIGALEA]

Hi everyone
Just wanted to know if its posisble to derive 5v from the PC serial port to drive the pic

Toni

[bitmaniac]

Hi!

A method that I have tried and works nice is the following:
9PIN Serial

pin6(DSR)+pin7(RTS)+pin8(CTS) wired together goes
through a diode 1n4148 to the input of a 78L05 . The ouput
of the 78L05 goes to pin14 (Vdd) of the pic and Here it is!
Don;t forget the ground pin5

(DSR)+(RTS)+(CTS)-----------|>-|------IN GND OUT ------(to Vdd pic)
........................................1N4148.... ......78L05....................PIC
Note: use only 78L05 regulator and you can also
put an electrolytic capacitor 10uf/16v to the input of 78L05 to the ground.

Attention: You can not draw to much mah from the serial port
but it is ok to supply a single pic and low currnet peripherals.

ALWAYS Use an extra serial card in you PC in order not to blow up
your on-board stuff!

[TONIGALEA]

thank you very much
i only need to use it to power a max232 as i have tried in vain to reduce the current taken from my pic when in sleep mode
but i still get about 3mA
so i just thought that if i power the max232 from the pc it should
draw current from the battery
when i completely remove both the 5v and gnd from the max232
my pic in sleep mode is 45uA which is good


Toni

[TONIGALEA]

Just a thought i am using a 9 way D-Type serial port