Re: Need help to extend capabilities of a simple proximity circuit
- From: Varactor <Moreflaps@xxxxxxxxx>
- Date: Sat, 26 Apr 2008 03:03:00 -0700 (PDT)
On Apr 26, 9:53 pm, axrock <chris.sef...@xxxxxxxxx> wrote:
Hi,Retriggerable monostable.
I am a total rookie when working with circuits, but I have built a kit
set transonic proximity sensor. I'll explain my use at the end.
Essentially what it does is turn on an LED when an object gets near to
the sensors. I have extended the kit with another kit to add relay
functionality. So when an object nears the sensor it switches the
relay. All this is a simple kit set circuit that runs on 12V.
My only problem with it, is the sensors a very touchy, when it senses
an odd shaped object (like a human or dog etc) the relay switches
madly on, off, on, off until the object is really close (EG: 2 Inches
etc).
I am wanting to add a delay to the circuit, so that when the relay
switches it stays on for at least 3 or 5 seconds. In other words, when
the sensor begins to detect the presence of an object rather than the
relay going nuts, it will actually stay on for at least 3 or 5 seconds
etc. When it is due to turn off again it will likely receive another
erratic pulse from the sensors due to the odd object near by. Hope
that makes sense.
What this is designed for:
Just in case you are curious.
I am attempting to build a device that will allow my dog to turn on an
outside tap to allow him to drink straight out of the hose. This way
he always has fresh water whenever he needs it. So far I have a
washing machine solenoid which switches on a home made pressure mat.
This does not work that well though. Hence, using a proximity sensor.
My dog just needs to walk up to the water outlet and the water turns
on. It works at the moment, but switches on and off very fast as he
gets within the distance I want. I need to set a timer of sorts
(possibly a 555) to keep the relay on rather than switch it off
immediately. This way it should keep the water flow steady for the
drink, and will turn off within 3 or 5 seconds of the dog moving away.
Really appreciate any help.
Really just need some help to add a small delay timer between the
sensor circuit and the relay circuit.
Cheers
.
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