[Noisebridge-discuss] PIR sensor docs

[Michael Shiloh]

Actually, just yesterday I came up with a project requiring short-range 
PIR sensing. I may grab a few to experiment.

Jonathan Foote wrote:
> I fooled with the passive IR sensor board a little. Managed to get a
> little more range out of it by putting a 500 ohm trimpot in parallel
> with R107 to lower the comparator threshold. However this only
> increases the range to about 18 inches or so before it starts to get
> noisy.
> 
> The first gain stage is some sort of differentiating amplifier, but
> not of a topology I'm familiar with, and I'm not sure how to hack it.
> Increasing noninverting feedback R should increase the gain, but it's
> already >1M, and more gain will at some point result in more false
> alarms. Any analog heads care to comment?
> https://www.noisebridge.net/wiki/Image:PIR_skeem_Sensor.jpg
> 
> But here are some lenses designed exactly for the two-element sensor.
> At 35 cents each they won't break the bank.
> http://www.futurlec.com/PIR_Sensors.shtml
> 
> 
> On Thu, Apr 16, 2009 at 8:08 AM, Mitch Altman <maltman23 at hotmail.com> wrote:
>> David, the guy who donated the box of sensors, said that there used to be
>> some lens that went with each sensor.  He had a lot of them, but couldn't
>> find them when he donated the box to us.  So, they are probably lost.  He
>> said the lense was used for sensing longer distances.  We may be able to get
>> some lenses that were intended for other purposes to work well enough for
>> our sensors -- but I'm not sure what kind of lens would be good.
>>
>>
>> Mitch.
>>
>>
>>
>>
>> --------------
>>
>>> Date: Wed, 15 Apr 2009 18:35:09 -0700
>>> Subject: Re: [Noisebridge-discuss] PIR sensor docs
>>> From: jtfoote at ieee.org
>>> To: maltman23 at hotmail.com
>>> CC: rachel at xtreme.com; noisebridge-discuss at lists.noisebridge.net
>>>
>>> The PIR range is pretty short, 12-18 inches.
>>>
>>> I know PIR sensors can sense an entire room (for intruder alarm
>>> applications) so I'd be surprised if we couldn't up the gain by
>>> tweaking some of the resistors. Increasing the range may be as easy as
>>> changing the threshold of the output comparator (u102b in the
>>> schematics). When I get a minute I'll put a scope on the amp output
>>> (u102a) and take a look.
>>>
>>>
>>> On Tue, Apr 14, 2009 at 11:21 AM, Mitch Altman <maltman23 at hotmail.com>
>>> wrote:
>>>> That's really cool, Jonathan.  Thanks for pioneering.  :)  By chance did
>>>> you
>>>> test the range?  You know how far away (or close) does your waving hand
>>>> need
>>>> to be for the PIR to get the nice High output?
>>>>
>>>>
>>>> Mitch.
>>>>
>>>>
>>>>
>>>>
>>>> ---------------
>>>>
>>>>> Date: Mon, 13 Apr 2009 19:11:18 -0700
>>>>> Subject: Re: [Noisebridge-discuss] PIR sensor docs
>>>>> From: jtfoote at ieee.org
>>>>> To: rachel at xtreme.com
>>>>> CC: noisebridge-discuss at lists.noisebridge.net
>>>>>
>>>>> I powered one up the other day, put a scope on the sensor output, and
>>>>> it works great. Beautiful logic high when you wave your hand over it.
>>>>> Details on wiki.
>>>>>
>>>>> Can probably hack range and sensitivity but not there yet.
>>>>>
>>>>> Thanks Rachel and Mitch for docs.
>>>>>
>>>>> On 4/13/09, Rachel McConnell <rachel at xtreme.com> wrote:
>>>>>> So remember those 900 free sensor boards that were donated? We did
>>>>>> get
>>>>>> documentation for them. Miloh was kind enough to put the docs up
>>>>>> after
>>>>>> I biffed. They've been up for a little while now but I don't think he
>>>>>> emailed the list. In case you were waiting, check out:
>>>>>>
>>>>>> https://www.noisebridge.net/wiki/PIR_Sensors
>>>>>> https://www.noisebridge.net/wiki/PIR_motion_sensor_schematics
>>>>>>
>>>>>> The first page has some PDF docs as well.
>>>>>>
>>>>>> Rachel
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