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Subject: Re: Timer circuit for relay?
Date: Fri, 4 Oct 2002 10:44:48 -0700
References: <0001HW.B9BF07130030FEA7165FEAC0@news.covad.net> <firstname.lastname@example.org> <0001HW.B9C30A9400B47E5B165FEAC0@news.covad.net>
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To recap, my goal is to trigger a small relay once an hour (approximately)
for a period of 10 minutes (approximately).
My current plan is to run an astable 555 at 1 sec period. This will input to
a 4040 CMOS decade counter which will count for 1-hour (approximately). This
output will trigger a monostable 555 to set its output for 10 minutes. Relay
is connected to this output.
I want to provide a push button to reset the circuit and trigger the
10-minute monostable 555. I'm not sure if resetting this 555 will result in a
high output, or a low output. Does resetting a 555 start the timing sequence
(output high)? Or is it go "off", awaiting the next trigger input? (The 555
data sheet doesn't specify.)
Ideally, I'd like to reset the decade counter, but I'm not sure if this sets
the outputs high or low for the duration of the reset. If high then low, this
would trigger the 10-minute 555, which is my goal. (The 4040 data sheet
I lack experience to know how the outputs behave during a reset. Can someone
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