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Main => Main Forum => Topic started by: Effayy on August 02, 2005, 10:44:36 am

Title: +5v from DB9 serial port?
Post by: Effayy on August 02, 2005, 10:44:36 am

Tried searching through Google, but to be honest, if the answer was staring me in the face, I wouldn't realize it.  :-\

I have the connectors and cabling needed to attach my new 4x40 LCD to my DB9 serial port, but can you draw +5v from it, or would I need to get my power from elsewhere?

I'm assuming that old DB9 prephirals (mice etc) had to draw power to send a signal, right?

- FA

Title: Re: +5v from DB9 serial port?
Post by: RandyT on August 02, 2005, 10:54:52 am

If I'm not mistaken, they siphon power from the CD and/or other lines.  The signals are +12v and -12v, but at very low current levels.

I don't think I would try to power a device like you are describing from them.  Remember, a mouse is only a small, low-power chip and a couple of opto-components, so it doesn't need much power.

RandyT

Title: Re: +5v from DB9 serial port?
Post by: ultramagnus on August 02, 2005, 10:56:26 am

erg, try to draw enough currernt to power a lcd from your serial port and you blow the port

either take it from the molex connectors in your pc (yellow, 12v, red, 5v) or from the power lines in a USB cable (5v)