Using PC parallel port as power supply

[Spectacular Butter]

Since my circuit requires a 5v power supply, can i use the parallel port to power up my circuit since the output from parallel port is 5v? Is it advisable or are there any drawbacks to using this besides having to need the pc (i can switch between using pc and battery)?

 

[Juglenaut]

Current draw limitations.

 

[Nigel Goodwin]

You also have voltage limitations as well, the port ouputs are likely to be less than 5V - by ANDing the outputs together (with diodes) you can generate a few milliamps, I have an external A2D that works like that (built in a D plug).

You should be VERY aware though, that modern parallel ports are part of the motherboard, killing your port would require the motherboard replacing! - and it's quite easy to kill these integrated ports!.

 

[FRIED]

Get a plug-in board, cheap insurance.

 

[Styx]

or use the usb port?

again a power limitatio but a bit more juice
Or get a veroboard in PCI formfacter from RS/FARNELL and jack into the PCI power bus - lots-o-power availble.

Or just use a molex splitter and use one of the 12V or 5V power leads that are always in your PC

 

[JohnBrown]

- by ANDing the outputs together (with diodes) you can generate a few milliamps,

???
I think that should be ORing!
But I also have an external A-D convertor that works in that way.

 

[Nigel Goodwin]

- by ANDing the outputs together (with diodes) you can generate a few milliamps,

???
I think that should be ORing!

True!