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In article . com,
wrote:

I need to design a circuit that I can tell it to start (digitally), and
then it will tell me when 10 minutes have passed. I just need to be
pointed in the right direction. What's the difference bewteen a
timer/clock/counter. I have a good understanding of circuit theory but
does anyone know of a good IC that can be surface mounted (and is
cheap) that I shoulod use. Any help or tips are greatly appreciated

James-

A simple timer might consist of a resistor charging a capacitor, with a
level detector used to determine when the desired time has been reached.
A more sophisticated timer would use flip-flops to count pulses, with
logic gates set to output a pulse when the state of the flip-flops reaches
a predetermined value.

A "counter" usually refers to an arrangement where counting is done only
during a precise period called the timebase. The result is counts per
unit time, usually expressed in Hertz (Hz), or counts per second. A
free-running counter would continue counting until told to stop, and the
results would just be the number of pulses received since the count was
started.

There is an IC that might get you started, the NE-555. Other sources make
it, but always with the "555" number.

This chip can be configured to start timing on command, and charge-up a
capacitor through a resistor, until a preset time has past. At that point
it should reset and generate an output pulse or level shift.

The trouble with this approach is that it is best for short time delays.
Ten minutes is a relatively long time, so circuit leakage may cause the
delay to be longer than what you would calculate based on the R-C time
constant.

Another approach to timing, is to count a clock, such as the NE-555 being
used as an oscillator or using the 60 Hz powerline frequency. The counter
would be started by your digital signal. When the counter reaches a
predetermined value, it should reset itself and generate an output pulse
or level shift. This method is better for long delays, and is less
affected by circuit tolerances.

Does this help?

Fred