From: "Graham Holloway"
Subject: Re: Timer circuit for relay?
Date: Tue, 1 Oct 2002 16:20:04 +0100
NNTP-Posting-Date: Tue, 1 Oct 2002 15:24:05 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Try looking at the 4000 CMOS series XXX 4541. Oscillator and counter
combined. Good for quite long periods with reasonable value components.
Philips Electronics web site for data.
"DaveC" wrote in message
> Posted elsewhere in these groups is my original question, "555 Timer
> Well, I thought that there might be another way to approach this circuit.
> I need to turn on a relay once an hour for a few minutes. The "once an
> needs to be adjustable -- maybe between 45 and 75 minutes, and the "few
> minutes" should be between 5 and 20 minutes.
> How about running a 555 to generate a clock signal as in input to a
> which, once an hour, outputs a signal (ie, goes low). This triggers
> 555 which closes the relay for the shorter period.
> If the clock signal 555 is adjustable -- say, plus and minus 40 percent,
> "once an hour" output from the counter will change accordingly (ie,
> earlier or later).
> The relay-controlling 555 will be simple, adjustable 555 monostable
> Constructive criticism? Ways to improve on this?
> Note that my return address is corrupted in an attempt to reduce spam. If
> choose to e-mail me, please correct my address as described below.
> Dave Carpenter
> Sound Logic
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