Cheapest object sensor on the market!

On Sun, 06 Apr 2008 15:54:04 -0500, raedarrar <info@0-800.tv> wrote:
>>On Apr 6, 1:15 pm, "raedarrar" <i...@0-800.tv> wrote:
>>> What are you trying to measure?
>>>
>>> I am not trying to measure a distance, but want to detect a hand or a
>>> finger when it comes within 50mm to 100mm.
>>
>>Can you detect change in lighting?
>>

>I only need to detect the presence of a hand! if detect change in lighting
>maybe in a situation where a changing in room lighting might get in
>conflict without the presence of the hand, how would i control it in order
>not to happen?

send pulses to an LED.  Detected the reflected light.  Ignore light that
doesn't appear to be from the LED pulses.

On Apr 6, 2:38 pm, "raedarrar" <i...@0-800.tv> wrote:
> >You are not telling us what to do with the hand wavings.  If you are
> >using it to turn on the device, false triggers (room lighting changes)
> >might not matter.  If you are using it to count votes, then it does
> >matter.
>
> Every time the device detects object in this case hands or fingers, i need
> it to count votes as long as its on. any advice?

More questions:
1. Is the device fixed or movable?
2. Can it use motion sensors?
3. How many digits of countings?

$3 to $5 would be doable.  $1 is wishful thinking.

>On Apr 6, 5:02=A0pm, linnix <m...@linnix.info-for.us> wrote:
>
>> You can detect rapid change in lighting, or even temperature if the
>
>Devices like motion-sensitive toys use an AC-coupled circuit triggered
>by a change in the resistance of a CdS cell. It's very cheap, but will
>be triggered every time the lights in a room are switched off and on.
>

Ok, on & off lights is a high contrast situation, i can use it in constant
light levels. 

what about using it in a constant room lights, then what would be the
detection distance between the hands and the device if i use an AC-coupled
circuit, can i determine the distance, and how far if so?

 

On Apr 6, 5:52=A0pm, "raedarrar" <i...@0-800.tv> wrote:

> detection distance between the hands and the device if i use an AC-coupled=

> circuit, can i determine the distance, and how far if so?

You cannot determine the distance. You can detect if someone walks by
or if someone waves a hand over the sensor. You can't tune the circuit
to trigger on a finer resolution than that.

On Apr 6, 5:38=A0pm, linnix <m...@linnix.info-for.us> wrote:
> > MSP430F20xx, which is very cheap in large quantity - well under your
> > price target.
>
> Probably not. =A0The OP wants $1 total BOM. =A0Lets figure 0.25 for PCB,
> 0.25 for LCD, 0.40 for LCD controller. =A0The uC needs to be less

No, you can drive the glass directly from the MSP430. So 0.25 for PCB,
0.25 for LCD leaves 0.50 for the micro. Definitely achievable in
volume.

raedarrar wrote:
>> You are not telling us what to do with the hand wavings.  If you are
>> using it to turn on the device, false triggers (room lighting changes)
>> might not matter.  If you are using it to count votes, then it does
>> matter.
>>
> 
> Every time the device detects object in this case hands or fingers, i need
> it to count votes as long as its on. any advice?

Ok, now that you have stated what you could have said in your first post.

How about an LED modulated with 40KHz.
A photo-detector can detect the reflection of the 40Khz.
The strength of the reflection can give a simple distance.

donald

On Apr 6, 5:45=A0pm, AZ Nomad <aznoma...@PremoveOBthisOX.COM> wrote:

> send pulses to an LED. =A0Detected the reflected light. =A0Ignore light th=
at
> doesn't appear to be from the LED pulses.

This sounds like the basic theory of the ultimate sort algorithm -
Arrange the objects to be sorted randomly. In at least one parallel
universe, this will result in a sorted array. So the algorithm is:
Arrange objects randomly. Check to see if they are in order. If not,
destroy the universe.

>> MSP430F20xx, which is very cheap in large quantity - well under your
>> price target.
>
>Probably not.  The OP wants $1 total BOM.  Lets figure 0.25 for PCB,
>0.25 for LCD, 0.40 for LCD controller.  The uC needs to be less than
>10 cents.
>
>

You are right, i have already a solution from cypress, the CapSens plus
http://www.cypress.com/capsense/

i have already called and it runs for $1.40 may be gets down to a $1 for
100,000 units, which its my purchasing volume as a start up.

there is another solution that runs for less, around $0.80 from Avago -
HSDL 9100-21

http://www.avagotech.com/search/results.jsp?src=&siteCriteria=hsdl+9100&searchButton.x=0&searchButton.y=0

but i beleive will need a microcontroler that will add up at least $0.40
to the cost!

Any advices guys !!

>On Apr 6, 2:38 pm, "raedarrar" <i...@0-800.tv> wrote:
>> >You are not telling us what to do with the hand wavings.  If you are
>> >using it to turn on the device, false triggers (room lighting
changes)
>> >might not matter.  If you are using it to count votes, then it does
>> >matter.
>>
>> Every time the device detects object in this case hands or fingers, i
need
>> it to count votes as long as its on. any advice?
>
>More questions:
>1. Is the device fixed or movable?
>2. Can it use motion sensors?
>3. How many digits of countings?
>
>$3 to $5 would be doable.  $1 is wishful thinking.
>

1. Will be fixed.
2. Yes. this what i am looking for.
3. max. 9 votes counts, so its a 1 digit LCD.

I already have a solution that will go for &1.80 but i need a $1 selling
price as it will be a disposable item for a life span of 30 to 50 hours of
use.

On Apr 6, 2:59 pm, larwe <zwsdot...@gmail.com> wrote:
> On Apr 6, 5:38 pm, linnix <m...@linnix.info-for.us> wrote:
>
> > > MSP430F20xx, which is very cheap in large quantity - well under your
> > > price target.
>
> > Probably not.  The OP wants $1 total BOM.  Lets figure 0.25 for PCB,
> > 0.25 for LCD, 0.40 for LCD controller.  The uC needs to be less
>
> No, you can drive the glass directly from the MSP430.

The cheap one does not have integrated charge pump.
If you rely on constant 3V supply from a button cell, it will last
only a couple of hours.  LCD would be unreadable below 2.5V.  Avr169
can run for a few days, as  low as 1.8V, but not for under a dollar.

> So 0.25 for PCB,
> 0.25 for LCD leaves 0.50 for the micro. Definitely achievable in
> volume.