From: Terry Pinnell
Subject: Re: Electronics Newbie Needs Help With A Timer Delay Circuit...
Date: Tue, 01 Oct 2002 09:30:58 +0100
NNTP-Posting-Date: Tue, 1 Oct 2002 08:30:59 +0000 (UTC)
X-Newsreader: Forte Agent 1.92/32.572
firstname.lastname@example.org (Jake) wrote:
>Long story short, I had an idea for an information podium with a
>simple button and a light bulb that would illuminate a transparency
>revealing a message. However, to drive home a point of "our" need (the
>societal 'our') for instant gratification, I wanted to introduce a
>delay into the button circuit.
Jake: You need to specify a few more details. What delay do you want
between pressing the button and the lamp lighting? Do you want the
lamp to stay on permanently? If not, do you want it to go out
automatically after a certain time (how long)? Or do you want to
switch it off manually? If so, how - with another momentary contact
button, or a switch which cuts all DC power to the circuit? Also, a
rather simpler circuit is required if you use a switch (rather than a
momentary action button) to simultaneously apply DC power to the
circuit and trigger the initial delay. But is that an option here, or
are simple buttons mandatory?
You might also like to study the basic 555 timer circuit I've shown at
But note that you should add suitable triggering to that. You would
need a brief low-going pulse at pin 2 to start the monostable, i.e
make its output go high for the set time. For example, that could be a
normally open push-button connected from pin 2 to ground, with a 10K
resistor also connecting pin 2 to +5V.
And in your case, you might even need *two* similar circuits. After
buying some resistors and capacitors, experiment a little and post
again. Conversely, it may well be that a much simpler circuit is
possible, once your exact requirements are clear.
Hobbyist, West Sussex, UK