Thank you for all your suggestions. But in regards to the current capacity of
the dpot, I do'nt think that will be a problem. Reading the lm317 datasheet,
it appears that only a few uamps pass through the adjustment pin, which should
mean that the range across the dpot will be between 0 and GND. I will measure
it with an analog pot first tho, just to make sure. In relation however, I had
another simple question. I could use a mech. switch to turn on the adjustable
output (ie: from the output pin of the regulator to the jack or whatever), but
I was wondering if it were possible to use a mosfet/bjt triggered by 16f628?
I'm not too familiar with what sort of transistors to use since I have limited
experience in D to A interfacing, but would this suggestion work in place of a
mechanical switch? Considering that I could have 1.5A max running through the
output, would a transistor be able to handle this?

Thank you once again,

JAi

Quoting Bob Axtell <bob@EDTEC.COM>:

> Digital Pots are cute, but be sure to notice that the current capabilities
> of those pots is very small. Make sure that over the entire range of use
> that the current is not exceeded. The other limit is the fact that they only
> work within the GND-VCC range as it is connected.
>
> Have been very happy with their except for these limitations.
>
> This is my first posting to the PICLIST.
>
> --Bob Axtell
>
>
> ----- Original Message -----
> From: "Manu Nair" <mnair066@UOTTAWA.CA>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Saturday, November 02, 2002 9:20 AM
> Subject: Re: [PIC]: Controlling resistance
>
>
> > You can control the resistance by using a digital pot. You just send the
> > values of the resistance you want via SPI and then the digital pot will
> > adjust to it. Microchip, among others, makes a variety of them. Their part
> > number (Microchip's) starts with MCP41 /MCP42-then the value of the pot.
> > Application note AN746 from Microchip's website shows you how to interface
> a
> > PIC16F876 to their digital pots. I am sure you can figure out how to port
> it
> > over to the 16F628. Hope this helps.
> >
> > AN746
> > http://www.microchip.com/download/appnote/analog/mcp4xxxx/00746a.pdf
> >
> > \manu
> > _______________________
> > Manu Nair
> > mnair@email.sae.org
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: pic microcontroller discussion list
> > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Jai Dhar
> > Sent: November 1, 2002 9:54 PM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [PIC]: Controlling resistance
> >
> >
> > Hello,
> >
> > I am looking to make a simple linear psu using lm317/337's adjustable
> > regulators. Basically, they use a pot from 0 -> 5k to adjust the Vout. I
> was
> > wondering if there is a way I can control a resistance using a 16f628, so
> I
> > can incorporate a sort of digital feel to my psu. Thank you for your time,
> >
> > Jai
> >
> > ----------------------------------------
> > This mail sent through www.mywaterloo.ca
> >
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> >
>
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>




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