[OpenTRV-dev] Possible cheap 2V PIR

[Damon Hart-Davis]

I'm hoping that I could sample once per second or so, and only when the system was needing to sense occupancy to avoid invoking a setback, but yes, probably an external pre-amp and possibly a latch would be needed.

I may simply need to play with one and see what works.

Rgds

Damon

On 2 Apr 2013, at 10:03, Mike Stirling wrote:

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> ----------------original message-----------------
> From: "Damon Hart-Davis" EMAIL ADDRESS HIDDEN 
> To: "Closed list for developer discussions" EMAIL ADDRESS HIDDEN 
> Date: Tue, 2 Apr 2013 02:31:20 +0100
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>> Murata IRS-B210ST01-R1 or IRA-E710ST0 (RS has them). Might do 1 or 2 ulp on 10-bit 
>> ADC input... May order one to find out!
>> 
>> Difficult to see what (leakage) current draw might be...
>> 
> 
> I guess largely dependent on the signal conditioning circuit, but GBW requirements are low so CMOS op-amps should be fine, and these are very low power. You would want to do all the signal processing in analogue so that you have a wake-up source for the micro. Using the ADC would be power hungry.
> 
> Mike
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