56480Re: Sensor types
- Aug 1 9:12 AMGood 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
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
--- In firstname.lastname@example.org, "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
> batt full/low
> edge detect
> 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: email@example.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
> this case.(im an electrician and you arent dealing with live
> 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
> get the current. Step four, wish you had better solar cells
> peace out
> Jesse Meers
> just build it!
> --- In firstname.lastname@example.org, "Bill" <wjl82871@> wrote:
> > Hello,
> > I have a few little solar cells laying around. I know how to
> > voltage of the cell, but how do I find the amp output? Do I
> > make some sort of load and then put the VMM in series with the
> > Thank you for your help and time!
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