Simple PIR circuit, need review
Hi,
I'm working on a simple circuit. The idea is to have a portable device that lights up when I stand up at night.
I have a PIR sensor that triggers 3 LEDS.
I use a LM741 as an OpAmp
The leds are type 3528. Though these LEDs are supposed to be powered with 12v, I'll use a 9v battery.
My main concern is the battery life, tha'ts why I use 100k resistors in stand-by, to limit the current.
R3 is used to fine-tune the threshold on the inverting voltage.
PIR outputs:
3.3v when it detects motion,
?v otherwise (but yet >0)
Could anyone give me some tips or advice on how to improve my circuit?
Thanks,
Antonio
Discussions
4 years ago
IF your concerned about battery life then don't use a 9V battery. They do not have a good amount of capacity to start with .
Reply 4 years ago
Hi,
the fact is that using 6 1.5v batteries takes much fore space. and I'm concerned about battery life, because, 9v batteries have low capacity.
Reply 4 years ago
Yes 6 AA batteries would be much better then a 9V battery. Sure it takes up a lot of space but if you want better capacity using standard batteries it will take up space and add weight. Now if you go with a lithium Ion battery you can get better capacity at smaller sizes and lower weights.
Reply 4 years ago
And what about the circuit? No matter wich battery I use the question remains the same.
Reply 4 years ago
The LEDs need 12V So you give then 12V. You also need a current limiting resistor in line with the LEDs. Otherwise they will pull as much current as they can till either they give out or the battery does.