How well regulated is the +5v from using this method?  I would assume that
this is a pretty "clean" supply, but since my application will be using
ADC's I need a supply without a lot of ripples and what-not.  IIRC a
previous post stated that the keyboard +5v line could source 120ma.  Is
this correct?  I haven't calculated it all out, but my project should take
10-20ma max.

I really like this idea.  If the supply is clean enough I could make my DSO
adapter box with the aforementioned 5 pin DIN connectors and a 25 pin
connector for attaching a parallel cable and do away with the need for a 9v
battery and regulator.

Thanks,
Adam





byron@CC.GATECH.EDU on 01/22/99 06:43:03 PM

Please respond to PICLIST@MITVMA.MIT.EDU

To:   PICLIST@MITVMA.MIT.EDU
cc:    (bcc: Adam Bryant/PEAK/MOORE)
Subject:  Re: +5v from a PC parallel port




>
> Is it possible to get enough current from a PC parallel port to power a
PIC
> project.  I am building a DSO adapter for my PC that uses a 16C84, two
> MAX187 ADC's, and a 741 quad op-amp.  Can a parallel port supply this
much
> current?  Or would I be better off including a 9 volt battery and a
> regulator?
The only way to get current is via the port output pins. There isn't much
there.
My current way of powering PC connected projects is via the keyboard
connector.
I simply put two 5 pin DIN connectors on opposite sides of the project box,
wire the pins straight across, and pull +5 and ground into the project.
Then
all you need to do is plug the keyboard in one connector, and a 5 pin DIN
cable in the other.
I used this to provide power to my homemade PIC programmer. Works like a
champ, and has had no ill effects on the keyboard (which I'm using to type
this message).
BAJ