AVR-Chat

Have you tried the AVR analog comparator?

	Mark Jordan


On 31 Mar 2005 at 11:49, Chuck Hackett wrote:

> 
> I'm using a 741 op-amp to condition an input signal.  It's setup like a
> threshold detector to detect a voltage level between .1 and .6 volts
> (adjustable).  It's my understanding (and experience) that the 741 can not
> operate that close to one of its rail voltages so I need to supply it with a
> negative rail voltage (I'm thinking -9v).  I have 12v supplied to the rest of
> the circuitry and need to avoid having a second supply (remote location).  I was
> thinking that I could generate -9v using a 555 timer, caps, R's and diode to
> rectify a negative voltage.  Can someone point me to a web site circuit for this
> using a minimum of components?  I assume I only need a very small current.
> 
> In the short term (this weekend) I need to stick with the 741 which I have on
> hand but can someone recommend an inexpensive "rail to rail" op-amp that would
> be better for my final configuration which would eliminate the need for the
> second supply?
> 
> Thanks in advance for any guidance you can give.  I'm mostly listening on this
> list but I'm learning a lot.  Thanks to all contributors for the resource.
> Someone on the list recommended "Embedded C Programming and the Atmel AVR" to
> someone else.  I ordered the book and read it in short order.  I found it very
> helpful in my "getting up to speed" <g>.
> 
> Regards,
> 
> Chuck Hackett
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