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RE: [beam] FET for SimD1 V3 SE

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  • Wilf Rigter
    Hi Dave, The 2N7000 is commonly available and will work fine at 5V. For many applications that use a D1 solar engine, you will want to use up all stored
    Message 1 of 5 , Jun 3, 2001
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      Hi Dave,

      The 2N7000 is commonly available and will work fine at 5V. For many
      applications that use a "D1" solar engine, you will want to use up all
      stored energy after the SE triggers. Normally these SEs charge a battery or
      capacitor during the day and power a load as long as possible during the
      night. There is no merit in not using all stored energy as would be the case
      in a "popper" circuit driving a solar powered photovore, where the recharge
      time is proportional to the depth of discharge and where more frequent
      shallow discharges of energy might be more efficient than less frequent
      deeper discharges. It comes down to your application: the type of load you
      want to control with SIMD1 SE will determine the output device parameters
      and may even require some minor circuit adaptation (SIMD1-v4?)to optimize
      the circuit your application. As far as suitable FETs are concerned, there
      was some discussion on this recently in :

      http://groups.yahoo.com/group/beam/message/14560

      As noted, suitable TO92 style FETs are few and far between but there are
      some excelent choices in the TO220 style power FET family.

      regards

      wilf





      -----Original Message-----
      From: dgreen@... [mailto:dgreen@...]
      Sent: Sunday, June 03, 2001 3:03 AM
      To: beam@yahoogroups.com
      Subject: [beam] FET for SimD1 V3 SE


      I saw this message (copied below) posted a while ago and have
      an additional question: What specific FET would work best for
      the SimD1 V3 solar engine? anyone got a specific part #? would
      a 2N7000 work?

      dave


      --- In beam@y..., "Eric Seale" <Eric.Seale@p...> wrote:
      > --- In beam@y..., gord1812@n... wrote:
      > > now if there is a tutoral on the D1 SE ?
      > >
      > > I'm using Wilf Rigter's SIMD1 V2 diagram. Looking at the
      PNP or PNP
      > > version I see the load has 3 connections. I want to set up a
      FLED to
      > > flassh when the light goes down. ..Fled has two leads
      ...where/what is
      > > the
      > > 3rd connection???
      >
      > Sounds like you're working from this page:
      >
      > http://bftgu.botic.com/assy_se_noct_SIMD1V2.html
      >
      > The FLED's two leads need to connect to Vcc and ground; in
      order to
      > hook this up to a SIMD1 V2, you really need to add a FET (the 3
      leads
      > to the load are Vcc, Ground, and an enable -- the load needs to
      only
      > draw power when the enable is "high").
      >
      > Once you add a FET, you've really got a SIMD1 V3:
      >
      > http://bftgu.botic.com/assy_se_noct_SIMD1V3.html
      >
      > Then the FLED just goes where the "Pummer" block is drawn
      (observing
      > the proper polarity, natch').
      >
      > > I'd also like to use this circuit to run a P-vore's SE after the
      > > lights
      > > go down.
      >
      > That'd work too, though you'll have to be careful. Most P-vore
      > circuits are built as dual-SEs; they pretty much rely on having
      > incoming solar power in order to work. You might be better off
      to use
      > Bob Shannon's "Smart Cap" circuit (either Bob's original
      "Vore-n-More"
      > version, or my trimmed down variant):
      >
      > http://bftgu.botic.com/assy_se_noct_smartcap.html
      >
      > Eric
      > -----------------------------------------------------------------
      > Eric Seale | BEAM from the Ground Up!
      > bftgu@m... | http://bftgu.botic.com


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    • dgreen@subdimension.com
      Thanks for the reply, Wilf. Not having any FET s on hand, I went ahead and tried substituting a plain old 3904 NPN (not PNP as suggested on the BFTGU page)
      Message 2 of 5 , Jun 13, 2001
      • 0 Attachment
        Thanks for the reply, Wilf.

        Not having any FET's on hand, I went ahead and tried
        substituting a plain old 3904 NPN (not PNP as suggested on the
        BFTGU page) transistor for the FET in the SimD1 V3 - and it
        seems to work! Now that the basic circuit is functioning, I am on
        to subtler problems.
        I am trying to create a "cricket" circuit using a piezo buzzer. I'm
        using a FLED to "chirp" the buzzer on and off. The circuit works
        successfully when I test it with a lamp. However, to make it work
        with actual sunset will require some tweaking, as that is a much
        more gradual fading of the light. The circuit basically comes on if
        the solar cell voltage is less than the cap voltge, right? The
        problem is that the decreasing voltage in the discharging cap
        catches up with the not-so-quickly decreasing solar cell voltage,
        as the sun slowly sets.
        I had the idea this morning to put a small capacitor (100uF)
        across my added 3904 which seems to help a lot with getting a
        clean start to the chirping. Nonetheless, when the circuit stops
        beeping, I can get it to beep some more by completely blocking
        the solar cell with my hand. Maybe the answer is to use bigger
        capacitors at a lower voltage (using a 2.7v solar cell instead of
        3.5v?? )
        Or perhaps there is a way to make the circuit use the first pulse
        of energy that comes through as a trigger for a transistor(s) that
        stays on until the capacitor discharges regardless of anything
        else that happens with the light from that point on.
        Or is it part of the problem the fact that I substituted a 3904 for
        the FET?

        From its description, is seems that the SIMD1 Solar Regulator
        may have somewhat of a "latch on and stay on" capability, but 2V
        is too low for my FLED/piezo buzzer to run - is there a way to get
        the "latching on" that the Solar Regulator has, without the voltage
        regulation?

        Any thoughts would be appreciated.

        Thanks,

        Dave



        --- In beam@y..., Wilf Rigter <wilf.rigter@p...> wrote:
        > Hi Dave,
        >
        > The 2N7000 is commonly available and will work fine at 5V.
        For many
        > applications that use a "D1" solar engine, you will want to use
        up all
        > stored energy after the SE triggers. Normally these SEs charge
        a battery or
        > capacitor during the day and power a load as long as possible
        during the
        > night. There is no merit in not using all stored energy as would
        be the case
        > in a "popper" circuit driving a solar powered photovore, where
        the recharge
        > time is proportional to the depth of discharge and where more
        frequent
        > shallow discharges of energy might be more efficient than less
        frequent
        > deeper discharges. It comes down to your application: the
        type of load you
        > want to control with SIMD1 SE will determine the output device
        parameters
        > and may even require some minor circuit adaptation
        (SIMD1-v4?)to optimize
        > the circuit your application. As far as suitable FETs are
        concerned, there
        > was some discussion on this recently in :
        >
        > http://groups.yahoo.com/group/beam/message/14560
        >
        > As noted, suitable TO92 style FETs are few and far between
        but there are
        > some excelent choices in the TO220 style power FET family.
        >
        > regards
        >
        > wilf
        >
        >
        >
        >
        >
        > -----Original Message-----
        > From: dgreen@s... [mailto:dgreen@s...]
        > Sent: Sunday, June 03, 2001 3:03 AM
        > To: beam@y...
        > Subject: [beam] FET for SimD1 V3 SE
        >
        >
        > I saw this message (copied below) posted a while ago and
        have
        > an additional question: What specific FET would work best for
        > the SimD1 V3 solar engine? anyone got a specific part #?
        would
        > a 2N7000 work?
        >
        > dave
        >
        >
        > --- In beam@y..., "Eric Seale" <Eric.Seale@p...> wrote:
        > > --- In beam@y..., gord1812@n... wrote:
        > > > now if there is a tutoral on the D1 SE ?
        > > >
        > > > I'm using Wilf Rigter's SIMD1 V2 diagram. Looking at the
        > PNP or PNP
        > > > version I see the load has 3 connections. I want to set up a
        > FLED to
        > > > flassh when the light goes down. ..Fled has two leads
        > ...where/what is
        > > > the
        > > > 3rd connection???
        > >
        > > Sounds like you're working from this page:
        > >
        > > http://bftgu.botic.com/assy_se_noct_SIMD1V2.html
        > >
        > > The FLED's two leads need to connect to Vcc and ground; in
        > order to
        > > hook this up to a SIMD1 V2, you really need to add a FET (the
        3
        > leads
        > > to the load are Vcc, Ground, and an enable -- the load needs
        to
        > only
        > > draw power when the enable is "high").
        > >
        > > Once you add a FET, you've really got a SIMD1 V3:
        > >
        > > http://bftgu.botic.com/assy_se_noct_SIMD1V3.html
        > >
        > > Then the FLED just goes where the "Pummer" block is
        drawn
        > (observing
        > > the proper polarity, natch').
        > >
        > > > I'd also like to use this circuit to run a P-vore's SE after
        the
        > > > lights
        > > > go down.
        > >
        > > That'd work too, though you'll have to be careful. Most P-vore
        > > circuits are built as dual-SEs; they pretty much rely on having
        > > incoming solar power in order to work. You might be better
        off
        > to use
        > > Bob Shannon's "Smart Cap" circuit (either Bob's original
        > "Vore-n-More"
        > > version, or my trimmed down variant):
        > >
        > > http://bftgu.botic.com/assy_se_noct_smartcap.html
        > >
        > > Eric
        > > -----------------------------------------------------------------
        > > Eric Seale | BEAM from the Ground Up!
        > > bftgu@m... | http://bftgu.botic.com
        >
        >
        > To unsubscribe from this group, send an email to:
        > beam-unsubscribe@egroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to
        http://docs.yahoo.com/info/terms/
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