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Date:	Thu, 29 Mar 2012 16:28:41 -0400
Message-ID:	<CALSZ9grznvM0i=H_5hL3PXZy-UfCtC_aw_RGT112tpmfu2UgAQ@mail.gmail.com>
Subject:	[geda-user] Reed Switch vs Hall Sensor
From:	Rob Butts <r DOT butts2 AT gmail DOT com>
To:	geda-user AT delorie DOT com
Reply-To:	geda-user AT delorie DOT com

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I'm doing a simple proximity alarm for when a pouch is opened.  In my
original design I power a small 8 pin microchip 8 bit microcontroller with
a 3 volt coin battery along with a spdt reed switch and a small smt
buzzer.  When the pouch is closed a magnet is against the reed switch.
I pull the normally closed side of the switch (open with magnet) high and
monitor the switch with the micro.  When the pouch is opened the switch
closes and triggers a change of state on the micro input.  If the pouch is
opened the micro beeps the buzzer 4 times, if closed - twice.

I have been told hall switches are more reliable but they are all active
low.  Since this is powered by a small 3 volt coin battery I am trying to
reduce the power consumption.  My delemma is that hall sensors draw on
average 7mA in the active state which it will always be in.  Does anyone
know if reed switches are really unreliable?  Any ideas on how to do this
in low power?

Thanks

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<div>I&#39;m doing a simple proximity alarm for when a pouch is opened.=A0 =
In my original design=A0I power=A0a small 8 pin microchip 8 bit microcontro=
ller with a 3 volt coin battery=A0along with a spdt reed switch and a small=
 smt buzzer.=A0 When the pouch is closed a magnet is against the reed switc=
h.=A0 I=A0pull the normally=A0closed side of the switch (open with magnet)=
=A0high and monitor the switch with the micro.=A0 When the pouch is opened=
=A0the switch closes and triggers a change of state on the micro input.=A0 =
If the pouch is opened the micro beeps the buzzer 4 times, if closed - twic=
e.</div>
<div>=A0</div><div>I have been told hall switches are more reliable but the=
y are all active low.=A0 Since this is powered by a small 3 volt coin batte=
ry I am trying to reduce the power consumption.=A0 My delemma is that hall =
sensors draw on average 7mA in the active state which it will always be in.=
=A0 Does anyone know if reed switches are really unreliable?=A0 Any ideas o=
n how to do this in low power?</div>
<div>=A0</div><div>Thanks</div>

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