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56480Re: Sensor types

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  • wilf_nv
    Aug 1 9:12 AM
      Good idea!

      To provide interchangable sensor modules you can normalize all sensor
      outputs to proportional voltage outputs which can be compared and
      then generate an open or closed "switch" contact.

      For example, use a series load resistor or potentiometer to condition
      resistive sensors such as potentiometers, PDs, thermistors and LDRs
      to generate a voltage output.

      Next use an opamp to compare the sensor voltage output to a reference
      voltage or to another sensor's output voltage. When a sensor output
      is above a threshold or is greater than the output voltage of a
      second sensor the comparator output goes high.

      Each opamp output signal controls two 4066 type analog gates.
      Finally, the analog gate I/O pins connect like simple switch contacts
      to the rest of the robot control circuit to provide signal inversion,
      change time constants, discharge delay capacitors, multiplex control
      signals (for reversersing) or implement wired AND/OR logic gates.

      These modules can be a complete subsystem that can be preconfigured
      and plug interchangably into a protoboard or PCB.

      Here is a suggested form factor and connector layout to make it
      compatible with protoboard or a PCB. I assume standard through hole

      Each sensor module should be 1"x 1" with two IC sockets for mounting
      a LM358 and a CD4066 plus 4 resistors. External connections are made
      two 8 pin connectors made from single inline rows of IC machine
      sockets with 0.1 inch spacing between pins and positioned along the
      top and bottom edges of the module with 0.9 inch spacing between

      The top 8 pin connector is used to connect two passive or active
      sensors and two threshold adjustment pots to the (+/-) inputs of the
      dual opamps and also provides pins for Vcc and gnd. The bottom 8 pin
      connector provides 4 independent 4066 switch contacts to be
      connecteted to the main part of the control circuit.

      This allows the module to be plugged into a proto board with the dual
      8 pin machine sockets pins and the socket acting as female input
      connetors or as feedthroughs for external sensors leads and internal
      jumpers for the control output signals.

      The module can be raised up above the protoboard to provide access to
      the hidden contact strips underneath the module by stacking up
      another pair of 8 pin machine sockets on the the two rows of
      connector pins.

      The module circuit does not have to be a standalone daughter board
      but can also be integrated into the main circuit protoboard or PCB if
      desired to interchangably accomodate a wide variety of sensors.

      A standardized sensor subsystem would require more discussion and
      consensus on the internal circuit and connector pin assigment. If a
      common interface is agreed on, it may go some way to creating a line
      of circuit modules that can be connected together to provide plug and
      play capability.


      --- In beam@yahoogroups.com, "Mike Robertson" <mikerobe@...> wrote:
      > i need some ideas/schematics for sensors for my new bot....i want
      to have modular types that i can plug and swap to change the function
      of the bot.
      > some i thought of so far are
      > hot/cold
      > light/dark
      > batt full/low
      > edge detect
      > tilt
      > proximity
      > and any other range by ir or emf
      > oh and naturally the default touch switches....but they're
      > i need them to have high/low outputs to interface with the rest of
      the bot design
      > thanks Mike
      > i dont ask for much do i?? lol
      > ----- Original Message -----
      > From: Jesse
      > To: beam@yahoogroups.com
      > Sent: Tuesday, July 31, 2007 8:14 PM
      > Subject: [beam] Re: how to find capacity of solar cell?
      > hello Bill. (ever seen the movie kill bill? JK)
      > hooking up you meter in series is a way to read current, but you
      > remember that the load determines the current draw, well up to a
      max in
      > this case.(im an electrician and you arent dealing with live
      > here)
      > a way to calculate(someone correct me if need be)the current
      > is to use I = E/R, which is current equals voltage divided by
      > resistance. the current will be small, say in the miliamp range.
      > one, measure the resistance of the solar cell. Step two, measure
      > voltage. Step three, do some math: voltaged divided the
      resistance to
      > get the current. Step four, wish you had better solar cells
      > peace out
      > Jesse Meers
      > just build it!
      > --- In beam@yahoogroups.com, "Bill" <wjl82871@> wrote:
      > >
      > > Hello,
      > >
      > > I have a few little solar cells laying around. I know how to
      find the
      > > voltage of the cell, but how do I find the amp output? Do I
      need to
      > > make some sort of load and then put the VMM in series with the
      > circuit?
      > >
      > > Thank you for your help and time!
      > >
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