Help with PIR Motion Sensor output (3V, TTL?)

Other Hardware Sensors
1

Hi all,

I have a the following PIR Motion sensor working: https://www.sparkfun.com/products/8630 . The output of the sensor (HIGH when motion is detected) goes into the input of my Arduino and all works great. :slight_smile:

Now I'd like to run the sensor in "standalone" mode. The PIR sensor only needs power to operate and the output gives 3V, so you can attach a LED to it directly. But instead of the LED, I'd like to have an Arduino, which needs more power than the 3V (I tried connecting a 3.3V Arduino, but the output is not sufficient).

My guess is that I need to use a MOSFET/transistor (that is connected to the output of the PIR motion sensor) which powers the 2nd circuit (the Arduino). Can somebody confirm? Also I'd love to learn which MOSFET/transistor I need to use.

Some additional info: the PIR motion sensor keeps the HIGH output for a while (configurable), so I do not need a mechanism that is triggered and stays active longer than the HIGH output. Also, I'd like to run this thing on batteries. So in an ideal scenario the MOSFET/transistor or 2nd circuit don't consume any power when not activated.

Thanks for your help!
Jan

2

you could also use an analogRead() ... to read 3V .. dont forget to connect the grounds. probably fast enough

3

Thanks, but I can read the output successfully. :slight_smile: The thing I want to do is to use the output signal to turn on/off an Arduino.

4

you might put the Arduino in sleep mode instead?

5

That would be possible yes, but I'd consider that as a workaround.

I was hoping a MOSFET or another component could be using the output of the PIR sensor to activate a secondary circuit (like a relay to power higher voltages).

Jan