need help building a scmematic

[Widget]

I'm in need of a circuit that count down from 30 sec. with a trigger to add more time onto the counter and that will turn off a relay when it hit's zero, would also like to add a pause potion to the counter The part backlist and a scmematic drawing would help A LOT!!

If any on has made somthing like this or know where i could get a scmematic I would be very happy. :D

[Kevin Weddle]

I am not sure this will have any meaning here, but there is a way to generate a one shot from the occurance of the input. Take the output of a logic gate and add put an inductor to ground. This will give you a charge of 5volts for an amount of time.

[Widget]

I'm looking for a circuit the has a 3 - 7 segment displays, to show minutes and seconds, a start and pause and reset trigger, and an add time trigger that starts @ 30 sec. and all of this will have to trigger a relay that will switch 110 V off after the count has reached zero..

[surajbarkale]

Your best bet is to use a microcontroller. A 20 pin will do the job & will cost less than discrete logic. You can use a CPLD also but then I don't know the prise factor.

[Widget]

do you have any ideas on what type of chip or info on where i could get home help to build this problem child of mine

[MP]

Here is a short tutorial on counters. This might help.

MP

Counters.zip