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Thread: Help on PIR connected to stamp2.

  1. #1

    Default Help on PIR connected to stamp2.

    Hi all,

    My project is a Surveillance system for my final project of my degree. I
    bought a BS2 starter kit, so I have the carrier Board.

    I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    to my BS2.
    This is probably a really simple query but:-
    I welcome any advice on
    where to buy a suitable PIR sensor and
    on how you connect a PIR to the BS2.


    Cheers,

    KATH
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  2. #2

    Default

    > where to buy a suitable PIR sensor and
    > on how you connect a PIR to the BS2.

    Try acroname for the Eltec sensor, they have project notes on how to hook
    it to a basic stamp using a comparator. It's easy to interface following
    their instructions.

    Good luck,

    Jim Munro
    <jimmn@x...>
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  3. #3

    Default

    > My project is a Surveillance system for my final project of my degree. I
    > bought a BS2 starter kit, so I have the carrier Board.
    >
    > I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    > to my BS2.
    > This is probably a really simple query but:-
    > I welcome any advice on
    > where to buy a suitable PIR sensor and
    > on how you connect a PIR to the BS2.

    Check out http://www.mpja.com. They often have very reasonably priced
    PIR kits or sensors.

    DLC
    --
    ================================================== ==========================
    * Dennis Clark Aristocrat at heart dlc@v... www.verinet.com/~dlc *
    * Be well, do good work, and stay in touch -- Garrison Keillor *
    ================================================== ==========================
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  4. #4

    Default

    Well, try www.acroname.com. If you want to measure the votage, and tell the
    direction of travel, etc. Then you will need a ADC, which the BS don't have.
    Try http://www.geocities.com/SiliconValley/Orchard/6633/ Shaun has a good
    tutorial on making a ADC for real cheap (the chip is free from Maxim). If
    you just want an off/on PIR detection you can always hack a motion detector
    from Wal-Mart. Try www.seattlerobtics.org and go to the encoder and search
    for the article on hacking the PIR sensor.
    -William

    ----- Original Message -----
    From: Kath <Kath@i...>
    To: <basicstamps@egroups.com>
    Sent: Thursday, March 30, 2000 10:35 AM
    Subject: [basicstamps] Help on PIR connected to stamp2.


    > Hi all,
    >
    > My project is a Surveillance system for my final project of my degree. I
    > bought a BS2 starter kit, so I have the carrier Board.
    >
    > I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    > to my BS2.
    > This is probably a really simple query but:-
    > I welcome any advice on
    > where to buy a suitable PIR sensor and
    > on how you connect a PIR to the BS2.
    >
    >
    > Cheers,
    >
    > KATH
    >
    >
    > ------------------------------------------------------------------------
    >
    > eGroups.com home: http://www.egroups.com/group/basicstamps
    > http://www.egroups.com - Simplifying group communications
    >
    >
    >
    >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  5. #5

    Default

    This is something that Tracy Allen sent to me, It works! I also hacked an alarm
    sensor and
    had it working at 30+ feet good luck.

    The usual PIR sensor produces a tiny voltage that has a peak frequency
    response at around 0.1 hertz-->10 hertz, and drops off rapidly at DC and at
    higher frequencies. So you need a high-gain AC preamp. The Phillips
    app-notes recommend an op-amp circuit that self-biases for zero output at
    DC:

    +Vcc
    --- Vcc
    | | signal |\| LM358
    | |---------------|+\
    |PIR| | >-----;- AC gain x1000, DC gain=0.
    | | ;-- |-/ |
    --- | |/ |
    | | |
    | ;--/\/\---'----/\/\----'
    | | 1k 1M
    | === 10uf
    | |
    Vss

    For longer range you have to use lenses. There are several companies that
    make infrared lenses commonly found on burglar alarms. The multifaceted
    Fresnel lenses break up the hot body walking by into an AC signal on the
    sensor. The lens is not necessary for detecting a hot body within that
    shorter 3-foot range. A company called "Fresnel Technologies" makes many
    patterns of lenses for special applications. I've used 4" diameter
    circular lenses & PIR for counting bats and other animals for field
    biology.

    -- Tracy Allen
    http://www.emesystems.com
    mailto:emesys@c...




    Kath wrote:
    >
    > Hi all,
    >
    > My project is a Surveillance system for my final project of my degree. I
    > bought a BS2 starter kit, so I have the carrier Board.
    >
    > I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    > to my BS2.
    > This is probably a really simple query but:-
    > I welcome any advice on
    > where to buy a suitable PIR sensor and
    > on how you connect a PIR to the BS2.
    >
    > Cheers,
    >
    > KATH
    >
    > ------------------------------------------------------------------------
    >
    > eGroups.com home: http://www.egroups.com/group/basicstamps
    > http://www.egroups.com - Simplifying group communications
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  6. #6

    Default

    Thanks for the help
    - have ordered a sensor from acroname.

    Cheers,

    Kath.
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  7. #7

    Default

    Hey Larry and Tracy, I've been meaing to ask about this. Can I just hack a
    security alarm, and desolder the actual PIR? It looks like a can with three
    leads and a window at top. I can't decipher much from your art. Can you send
    me a shemo? Thanks a bunch. BTW I'd like to do this with Rat Shack
    components. Feasible?
    -William

    ----- Original Message -----
    From: LarryGaminde <lgaminde@t...>
    To: <basicstamps@egroups.com>
    Sent: Thursday, March 30, 2000 10:43 PM
    Subject: [basicstamps] Re: Help on PIR connected to stamp2.


    > This is something that Tracy Allen sent to me, It works! I also hacked an
    alarm sensor and
    > had it working at 30+ feet good luck.
    >
    > The usual PIR sensor produces a tiny voltage that has a peak frequency
    > response at around 0.1 hertz-->10 hertz, and drops off rapidly at DC and
    at
    > higher frequencies. So you need a high-gain AC preamp. The Phillips
    > app-notes recommend an op-amp circuit that self-biases for zero output at
    > DC:
    >
    > +Vcc
    > --- Vcc
    > | | signal |\| LM358
    > | |---------------|+\
    > |PIR| | >-----;- AC gain x1000, DC gain=0.
    > | | ;-- |-/ |
    > --- | |/ |
    > | | |
    > | ;--/\/\---'----/\/\----'
    > | | 1k 1M
    > | === 10uf
    > | |
    > Vss
    >
    > For longer range you have to use lenses. There are several companies that
    > make infrared lenses commonly found on burglar alarms. The multifaceted
    > Fresnel lenses break up the hot body walking by into an AC signal on the
    > sensor. The lens is not necessary for detecting a hot body within that
    > shorter 3-foot range. A company called "Fresnel Technologies" makes many
    > patterns of lenses for special applications. I've used 4" diameter
    > circular lenses & PIR for counting bats and other animals for field
    > biology.
    >
    > -- Tracy Allen
    > http://www.emesystems.com
    > mailto:emesys@c...
    >
    >
    >
    >
    > Kath wrote:
    > >
    > > Hi all,
    > >
    > > My project is a Surveillance system for my final project of my degree. I
    > > bought a BS2 starter kit, so I have the carrier Board.
    > >
    > > I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    > > to my BS2.
    > > This is probably a really simple query but:-
    > > I welcome any advice on
    > > where to buy a suitable PIR sensor and
    > > on how you connect a PIR to the BS2.
    > >
    > > Cheers,
    > >
    > > KATH
    > >
    > > ------------------------------------------------------------------------
    > >
    > > eGroups.com home: http://www.egroups.com/group/basicstamps
    > > http://www.egroups.com - Simplifying group communications
    >
    > ------------------------------------------------------------------------
    > -- Check out your group's private Chat room
    > -- http://www.egroups.com/ChatPage?list...asicstamps&m=1
    >
    >
    >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  8. #8

    Default

    What I did is hack a alarm sensor, I found the regulator and took it
    out ( the sensor ran off 12 vdc) so now all I needed was a 5 vdc
    supply. Next I removed the relay and installed a pot where the relay
    coil was connected then I hooked up the stamp pin to one side of pot.
    It is worked at long range because it came with a lens that fits the
    sensor housing and looks good. The reason I removed the relay was
    because of the power drain installing the pot allowed me to have the
    sensor still turn on and off reliably but with only 20 mA drain vs
    maybe 75mA ++. as far as viewing goes change from a variable width
    font to a fixed width font and you will be able to view he picture.

    William Ox wrote:
    >
    > Hey Larry and Tracy, I've been meaing to ask about this. Can I just hack a
    > security alarm, and desolder the actual PIR? It looks like a can with three
    > leads and a window at top. I can't decipher much from your art. Can you send
    > me a shemo? Thanks a bunch. BTW I'd like to do this with Rat Shack
    > components. Feasible?
    > -William
    >
    > ----- Original Message -----
    > From: LarryGaminde <lgaminde@t...>
    > To: <basicstamps@egroups.com>
    > Sent: Thursday, March 30, 2000 10:43 PM
    > Subject: [basicstamps] Re: Help on PIR connected to stamp2.
    >
    > > This is something that Tracy Allen sent to me, It works! I also hacked an
    > alarm sensor and
    > > had it working at 30+ feet good luck.
    > >
    > > The usual PIR sensor produces a tiny voltage that has a peak frequency
    > > response at around 0.1 hertz-->10 hertz, and drops off rapidly at DC and
    > at
    > > higher frequencies. So you need a high-gain AC preamp. The Phillips
    > > app-notes recommend an op-amp circuit that self-biases for zero output at
    > > DC:
    > >
    > > +Vcc
    > > --- Vcc
    > > | | signal |\| LM358
    > > | |---------------|+\
    > > |PIR| | >-----;- AC gain x1000, DC gain=0.
    > > | | ;-- |-/ |
    > > --- | |/ |
    > > | | |
    > > | ;--/\/\---'----/\/\----'
    > > | | 1k 1M
    > > | === 10uf
    > > | |
    > > Vss
    > >
    > > For longer range you have to use lenses. There are several companies that
    > > make infrared lenses commonly found on burglar alarms. The multifaceted
    > > Fresnel lenses break up the hot body walking by into an AC signal on the
    > > sensor. The lens is not necessary for detecting a hot body within that
    > > shorter 3-foot range. A company called "Fresnel Technologies" makes many
    > > patterns of lenses for special applications. I've used 4" diameter
    > > circular lenses & PIR for counting bats and other animals for field
    > > biology.
    > >
    > > -- Tracy Allen
    > > http://www.emesystems.com
    > > mailto:emesys@c...
    > >
    > >
    > >
    > >
    > > Kath wrote:
    > > >
    > > > Hi all,
    > > >
    > > > My project is a Surveillance system for my final project of my degree. I
    > > > bought a BS2 starter kit, so I have the carrier Board.
    > > >
    > > > I'm V. new to the Basic Stamp world and I want to connect a PIR sensor
    > > > to my BS2.
    > > > This is probably a really simple query but:-
    > > > I welcome any advice on
    > > > where to buy a suitable PIR sensor and
    > > > on how you connect a PIR to the BS2.
    > > >
    > > > Cheers,
    > > >
    > > > KATH
    > > >
    > > > ------------------------------------------------------------------------
    > > >
    > > > eGroups.com home: http://www.egroups.com/group/basicstamps
    > > > http://www.egroups.com - Simplifying group communications
    > >
    > > ------------------------------------------------------------------------
    > > -- Check out your group's private Chat room
    > > -- http://www.egroups.com/ChatPage?list...asicstamps&m=1
    > >
    > >
    > >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  9. #9

    Default

    Hmmm .... yes I did this according to the tutorial on SRS. I haven't been
    able to get it to work. But then again, I've only tried once :)
    Unfortunately the detector I'm using has a 4 second delay between updates.
    Isn't there any schematic out there about how to build you own circuit? I
    want one that gives a analog voltage (as opposed to digital off/on), like
    the Acroname one, without the price. I know this is really ambitious, but
    I'm interested....
    -William


    ----- Original Message -----
    From: LarryGaminde <lgaminde@t...>
    To: <basicstamps@egroups.com>
    Sent: Friday, April 07, 2000 2:11 PM
    Subject: Re: [basicstamps] Re: Help on PIR connected to stamp2.


    > What I did is hack a alarm sensor, I found the regulator and took it
    > out ( the sensor ran off 12 vdc) so now all I needed was a 5 vdc
    > supply. Next I removed the relay and installed a pot where the relay
    > coil was connected then I hooked up the stamp pin to one side of pot.
    > It is worked at long range because it came with a lens that fits the
    > sensor housing and looks good. The reason I removed the relay was
    > because of the power drain installing the pot allowed me to have the
    > sensor still turn on and off reliably but with only 20 mA drain vs
    > maybe 75mA ++. as far as viewing goes change from a variable width
    > font to a fixed width font and you will be able to view he picture.
    >
    > William Ox wrote:
    > >
    > > Hey Larry and Tracy, I've been meaing to ask about this. Can I just hack
    a
    > > security alarm, and desolder the actual PIR? It looks like a can with
    three
    > > leads and a window at top. I can't decipher much from your art. Can you
    send
    > > me a shemo? Thanks a bunch. BTW I'd like to do this with Rat Shack
    > > components. Feasible?
    > > -William
    > >
    > > ----- Original Message -----
    > > From: LarryGaminde <lgaminde@t...>
    > > To: <basicstamps@egroups.com>
    > > Sent: Thursday, March 30, 2000 10:43 PM
    > > Subject: [basicstamps] Re: Help on PIR connected to stamp2.
    > >
    > > > This is something that Tracy Allen sent to me, It works! I also
    hacked an
    > > alarm sensor and
    > > > had it working at 30+ feet good luck.
    > > >
    > > > The usual PIR sensor produces a tiny voltage that has a peak frequency
    > > > response at around 0.1 hertz-->10 hertz, and drops off rapidly at DC
    and
    > > at
    > > > higher frequencies. So you need a high-gain AC preamp. The Phillips
    > > > app-notes recommend an op-amp circuit that self-biases for zero output
    at
    > > > DC:
    > > >
    > > > +Vcc
    > > > --- Vcc
    > > > | | signal |\| LM358
    > > > | |---------------|+\
    > > > |PIR| | >-----;- AC gain x1000, DC gain=0.
    > > > | | ;-- |-/ |
    > > > --- | |/ |
    > > > | | |
    > > > | ;--/\/\---'----/\/\----'
    > > > | | 1k 1M
    > > > | === 10uf
    > > > | |
    > > > Vss
    > > >
    > > > For longer range you have to use lenses. There are several companies
    that
    > > > make infrared lenses commonly found on burglar alarms. The
    multifaceted
    > > > Fresnel lenses break up the hot body walking by into an AC signal on
    the
    > > > sensor. The lens is not necessary for detecting a hot body within that
    > > > shorter 3-foot range. A company called "Fresnel Technologies" makes
    many
    > > > patterns of lenses for special applications. I've used 4" diameter
    > > > circular lenses & PIR for counting bats and other animals for field
    > > > biology.
    > > >
    > > > -- Tracy Allen
    > > > http://www.emesystems.com
    > > > mailto:emesys@c...
    > > >
    > > >
    > > >
    > > >
    > > > Kath wrote:
    > > > >
    > > > > Hi all,
    > > > >
    > > > > My project is a Surveillance system for my final project of my
    degree. I
    > > > > bought a BS2 starter kit, so I have the carrier Board.
    > > > >
    > > > > I'm V. new to the Basic Stamp world and I want to connect a PIR
    sensor
    > > > > to my BS2.
    > > > > This is probably a really simple query but:-
    > > > > I welcome any advice on
    > > > > where to buy a suitable PIR sensor and
    > > > > on how you connect a PIR to the BS2.
    > > > >
    > > > > Cheers,
    > > > >
    > > > > KATH
    > > > >
    > > >
    > ------------------------------------------------------------------------
    > > > >
    > > > > eGroups.com home: http://www.egroups.com/group/basicstamps
    > > > > http://www.egroups.com - Simplifying group communications
    > > >
    > >
    > ------------------------------------------------------------------------
    > > > -- Check out your group's private Chat room
    > > > -- http://www.egroups.com/ChatPage?list...asicstamps&m=1
    > > >
    > > >
    > > >
    >
    >
    >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  10. #10

    Default

    Yes I had a delay also not 4 seconds but there was a delay when it
    turned on it stayed on for maybe a second or two, as far as variable
    voltage I can't help (what advantage would this have ?) I could see if
    you were looking for temp using IR but what advantage for detecting a
    hot body walking by. There is a schematic, I sent it with the first
    mail try to highlight it copy it and then use notepad and view it
    there but again its only on / off Sorry.

    William Cox wrote:
    >
    > Hmmm .... yes I did this according to the tutorial on SRS. I haven't been
    > able to get it to work. But then again, I've only tried once :)
    > Unfortunately the detector I'm using has a 4 second delay between updates.
    > Isn't there any schematic out there about how to build you own circuit? I
    > want one that gives a analog voltage (as opposed to digital off/on), like
    > the Acroname one, without the price. I know this is really ambitious, but
    > I'm interested....
    > -William
    >
    > ----- Original Message -----
    > From: LarryGaminde <lgaminde@t...>
    > To: <basicstamps@egroups.com>
    > Sent: Friday, April 07, 2000 2:11 PM
    > Subject: Re: [basicstamps] Re: Help on PIR connected to stamp2.
    >
    > > What I did is hack a alarm sensor, I found the regulator and took it
    > > out ( the sensor ran off 12 vdc) so now all I needed was a 5 vdc
    > > supply. Next I removed the relay and installed a pot where the relay
    > > coil was connected then I hooked up the stamp pin to one side of pot.
    > > It is worked at long range because it came with a lens that fits the
    > > sensor housing and looks good. The reason I removed the relay was
    > > because of the power drain installing the pot allowed me to have the
    > > sensor still turn on and off reliably but with only 20 mA drain vs
    > > maybe 75mA ++. as far as viewing goes change from a variable width
    > > font to a fixed width font and you will be able to view he picture.
    > >
    > > William Ox wrote:
    > > >
    > > > Hey Larry and Tracy, I've been meaing to ask about this. Can I just hack
    > a
    > > > security alarm, and desolder the actual PIR? It looks like a can with
    > three
    > > > leads and a window at top. I can't decipher much from your art. Can you
    > send
    > > > me a shemo? Thanks a bunch. BTW I'd like to do this with Rat Shack
    > > > components. Feasible?
    > > > -William
    > > >
    > > > ----- Original Message -----
    > > > From: LarryGaminde <lgaminde@t...>
    > > > To: <basicstamps@egroups.com>
    > > > Sent: Thursday, March 30, 2000 10:43 PM
    > > > Subject: [basicstamps] Re: Help on PIR connected to stamp2.
    > > >
    > > > > This is something that Tracy Allen sent to me, It works! I also
    > hacked an
    > > > alarm sensor and
    > > > > had it working at 30+ feet good luck.
    > > > >
    > > > > The usual PIR sensor produces a tiny voltage that has a peak frequency
    > > > > response at around 0.1 hertz-->10 hertz, and drops off rapidly at DC
    > and
    > > > at
    > > > > higher frequencies. So you need a high-gain AC preamp. The Phillips
    > > > > app-notes recommend an op-amp circuit that self-biases for zero output
    > at
    > > > > DC:
    > > > >
    > > > > +Vcc
    > > > > --- Vcc
    > > > > | | signal |\| LM358
    > > > > | |---------------|+\
    > > > > |PIR| | >-----;- AC gain x1000, DC gain=0.
    > > > > | | ;-- |-/ |
    > > > > --- | |/ |
    > > > > | | |
    > > > > | ;--/\/\---'----/\/\----'
    > > > > | | 1k 1M
    > > > > | === 10uf
    > > > > | |
    > > > > Vss
    > > > >
    > > > > For longer range you have to use lenses. There are several companies
    > that
    > > > > make infrared lenses commonly found on burglar alarms. The
    > multifaceted
    > > > > Fresnel lenses break up the hot body walking by into an AC signal on
    > the
    > > > > sensor. The lens is not necessary for detecting a hot body within that
    > > > > shorter 3-foot range. A company called "Fresnel Technologies" makes
    > many
    > > > > patterns of lenses for special applications. I've used 4" diameter
    > > > > circular lenses & PIR for counting bats and other animals for field
    > > > > biology.
    > > > >
    > > > > -- Tracy Allen
    > > > > http://www.emesystems.com
    > > > > mailto:emesys@c...
    > > > >
    > > > >
    > > > >
    > > > >
    > > > > Kath wrote:
    > > > > >
    > > > > > Hi all,
    > > > > >
    > > > > > My project is a Surveillance system for my final project of my
    > degree. I
    > > > > > bought a BS2 starter kit, so I have the carrier Board.
    > > > > >
    > > > > > I'm V. new to the Basic Stamp world and I want to connect a PIR
    > sensor
    > > > > > to my BS2.
    > > > > > This is probably a really simple query but:-
    > > > > > I welcome any advice on
    > > > > > where to buy a suitable PIR sensor and
    > > > > > on how you connect a PIR to the BS2.
    > > > > >
    > > > > > Cheers,
    > > > > >
    > > > > > KATH
    > > > > >
    > > > >
    > > ------------------------------------------------------------------------
    > > > > >
    > > > > > eGroups.com home: http://www.egroups.com/group/basicstamps
    > > > > > http://www.egroups.com - Simplifying group communications
    > > > >
    > > >
    > > ------------------------------------------------------------------------
    > > > > -- Check out your group's private Chat room
    > > > > -- http://www.egroups.com/ChatPage?list...asicstamps&m=1
    > > > >
    > > > >
    > > > >
    > >
    > >
    > >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  11. #11

    Default

    > Hey Larry and Tracy, I've been meaing to ask about this. Can
    > I just hack a security alarm, and desolder the actual PIR?
    > It looks like a can with three leads and a window at top.
    > I can't decipher much from your art. Can you send me a shemo?
    > Thanks a bunch. BTW I'd like to do this with Rat Shack
    > components. Feasible?
    >.....
    > Unfortunately the detector I'm using has a 4 second delay between
    > updates. Isn't there any schematic out there about how to build
    > you own circuit? I want one that gives a analog voltage (as opposed
    > to digital off/on), like the Acroname one, without the price. I know
    > this is really ambitious, but
    > -William

    Hi William,
    Yes, the PIR from the alarm should work just fine. I guess you need
    faster response and an analog output, so you can't simply hack the whole
    alarm. I was faced with a similar need to make my own circuit, because it
    was for an animal counter for flying bats that had to respond very fast.
    I'll try again with the ascii art to show more of the connections and pin
    numbers:

    ;-------------------o-----------------Vcc 5 volts
    | |
    --- Vcc
    | | signal 3|\|8 LM358
    | |---------------|+\
    |PIR| | >1----o- AC gain x1000, DC gain=0.
    | | ;--|-/ |
    --- | 2|/|4 |
    | | | |
    | ;--/\/\---o----+-/\/\-'
    | | 1k | 1M
    | === 10uf |
    | | |
    '----o--------------o------- Vss

    The resting voltage level at both pin 3 and pin 1 of the op amp will be a
    few tenths of a volt, until something comes by that excites the PIR sensor.
    The voltage at the input pin 3 will shift by a few millivolts. The output
    at pin 1 will shift by a volt or more. The circuit tracks slow changes in
    the PIR output, with a time constant determined by the 1M resistor and the
    10uf capacitor. But the gain for fast changes is x1000, because of the
    ratio of 1M/1k resistors. This is a standard circuit for PIR sensors. It
    takes the circuit 10 or 20 seconds to "warm up" as the capacitor charges up
    to the resing level. What do you want to do with the analog signal once
    you have it? It could go into a comparator circuit to square up the level
    changes. More signal processing may be desireable to reject "false
    alarms".

    I hope that helps,

    -- Tracy Allen
    Electronically Monitored Ecosystems
    http://www.emesystems.com
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  12. #12

    Default

    Great! Frankly I don't really have much planned. I'd hoped just to give my
    bot the ability to detect people, and the direction their moving. I've also
    thought about the Trinity competition. I tried hacking just the motion
    sensor, but the 4 second time lag was just too much, no to mention the
    digital signal. This *seems* to be a simple circuit. How come so many people
    opt out for the $40 all in one from Acroname? I know it's a whole lot
    easier, but the price difference (IMHO) out weights it. I'll see what I can
    do with it. Thanks again. BTW I've understood that a PIR (such as the
    Acroname one) has a sine wave output (sort of), if a person was to walk
    across it. Is this true for this circuit?
    -William

    > Hi William,
    > Yes, the PIR from the alarm should work just fine. I guess you need
    > faster response and an analog output, so you can't simply hack the whole
    > alarm. I was faced with a similar need to make my own circuit, because it
    > was for an animal counter for flying bats that had to respond very fast.
    > I'll try again with the ascii art to show more of the connections and pin
    > numbers:
    >
    > ;-------------------o-----------------Vcc 5 volts
    > | |
    > --- Vcc
    > | | signal 3|\|8 LM358
    > | |---------------|+\
    > |PIR| | >1----o- AC gain x1000, DC gain=0.
    > | | ;--|-/ |
    > --- | 2|/|4 |
    > | | | |
    > | ;--/\/\---o----+-/\/\-'
    > | | 1k | 1M
    > | === 10uf |
    > | | |
    > '----o--------------o------- Vss
    >
    > The resting voltage level at both pin 3 and pin 1 of the op amp will be a
    > few tenths of a volt, until something comes by that excites the PIR
    sensor.
    > The voltage at the input pin 3 will shift by a few millivolts. The
    output
    > at pin 1 will shift by a volt or more. The circuit tracks slow changes in
    > the PIR output, with a time constant determined by the 1M resistor and the
    > 10uf capacitor. But the gain for fast changes is x1000, because of the
    > ratio of 1M/1k resistors. This is a standard circuit for PIR sensors. It
    > takes the circuit 10 or 20 seconds to "warm up" as the capacitor charges
    up
    > to the resing level. What do you want to do with the analog signal once
    > you have it? It could go into a comparator circuit to square up the level
    > changes. More signal processing may be desireable to reject "false
    > alarms".
    >
    > I hope that helps,
    >
    > -- Tracy Allen
    > Electronically Monitored Ecosystems
    > http://www.emesystems.com
    >
    >
    >
    >
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

  13. #13

    Default

    > BTW I've understood that a PIR (such as the Acroname one) has a sine
    > wave output (sort of), if a person was to walk
    > across it. Is this true for this circuit?

    It is true, under "ideal" conditions the signal looks like one cycle of a
    sine wave. You have to realize that the PIR sensor (most PIR sensors that
    is) contain a pair of heat sensitive elements hooked up in series
    opposition, kind of like:
    +--+
    like two tiny batteries hooked up so that their voltages cancel. For
    changes in ambient temperature and slow changes in infrared energy, the two
    voltages change by equal amounts, so they cancel. But the two elements are
    positioned side by side behind the window in the PIR package. The image
    of a warm object is focused by the lens that is normally put as a distance
    in front of the PIR sensor. As the image of the warm object moves across
    the sensor in one direction, it heats up first the (+-) element and then
    the (-+) element, so that you get first an excess of voltage in one
    direction and then in the other direction. It is like a single cycle of a
    sine wave. If the image of the object moves in the other direction, then
    you get the opposite phase. So under ideal circumstances you can tell
    which direction the object is moving by looking a the phase of the pulses.
    A positive cycle followed by a negative cycle is motion in one direction,
    while a negative cycle followed by a positive cycle is motion in the
    opposite direction. But I said "ideal"--caveat, the unrestained movement
    of bodies is seldom ideal. One half of the pulse may come out much larger
    than the other, or one half of the pulse may be missing altogther. BTW
    some of the cheapest PIR sensors only have one element:
    +-
    and have higher ambient drift and a different response characteristic.

    A lot depends on the lens that is put in front of the PIR sensor, because
    it is the lens that forms the sharp image. Some lenses have many facets
    that point in different directions into different zones. So a person
    walking across forms a whole succession of images that march across the
    face of the PIR sensor and make a sequence of signals. Other simple
    cylindrical lenses form one strong image. Lots of variation. See Fresnel
    Technologies site for an idea of the variety of lenses available:
    http://www.fresneltech.com/


    > This *seems* to be a simple circuit. How come so many people
    > opt out for the $40 all in one from Acroname? I know it's a whole lot
    > easier, but the price difference (IMHO) out weights it. I'll see what I
    can
    > do with it.

    I don't know about the Acroname circuit. Well, the circuit I gave is just
    a start. It is the core to allow you to get a big signal. But as you get
    into it more, you may find you need some more filtering or faster power on,
    or bells and whistles. Not to mention the lens and the enclosure and the
    PC board, and the engineering. I'd say $40 is not at all an unreasonable
    price! When I have made things like this for my clients, I have to charge
    them a lot more than that! This kind of circuit is built up of many
    blocks, and each block serves some simple purpose for what you or the
    commercial design was trying to accomplish. Maybe you just need the core of
    it to start with to experiment and learn.

    -- Tracy Allen
    Electronically Monitored Ecosystems
    http://www.emesystems.com
    Last edited by ForumTools; 09-30-2010 at 11:55 AM. Reason: Forum Migration

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