Drawing Power from an RS232 Port

[S. Ethier]

I am interested in drawing power from an RS232 port so that it powers an
external circuit, only I am not too sure where to begin. The RS232 port
is not on the DTE side, but on the DCE side. I was able to measure
-7.59V DC and -25mA on the following PINs using a digital multimeter:
RI, DSR, DCD, CTS.

Is it possible to draw power from this DCE so that I have +3.3V DC at
approximately 140mA for my circuit? Let me know what you guys think.

Steph

 

[Kevin R]

On Mon, 11 Apr 2005 16:09:52 -0400, "S. Ethier"
<sethier@linuxmail.org> wrote:

I am interested in drawing power from an RS232 port so that it powers an
external circuit, only I am not too sure where to begin. The RS232 port
is not on the DTE side, but on the DCE side. I was able to measure
-7.59V DC and -25mA on the following PINs using a digital multimeter:
RI, DSR, DCD, CTS.

Is it possible to draw power from this DCE so that I have +3.3V DC at
approximately 140mA for my circuit? Let me know what you guys think.

Steph

There's no way you're going to get 140mA from a serial port,
not at 3.3 volts anyway.

How about USB instead ?

 

[John Musselman]

Is it possible to draw power from this DCE so that I have +3.3V DC at
approximately 140mA for my circuit? Let me know what you guys think.

No, there's not that much power available. Not even from all the signal
lines combined.

John Musselman