Invert output signal of PIR sensor

Procast

Hello,

Is there an easy way or what is the easiest way to invert the output of the PIR sensor.
I'm using te sensor in combination with a media player that has more possibilities when detecting a low signal.
The input of the mediaplayer is driven high by a 1k resistor

tnx

C.

Publison

If it's a 5 volt device, a 7404 will suffice, but overkill for one input.

http://www.ti.com/lit/ds/symlink/sn74ls04.pdf

Procast

Problem is I have only 3.3V available from the mediaplayer

Publison

Have a look at this thread:

http://www.savagecircuits.com/content.php?85-Mixed-Voltage-Systems-Interfacing-5V-and-3-3V-Devices

Procast

Yeah, could use an opto coupler, would be quite simple

Duane Degn

Here's another option.

http://www.digikey.com/product-detail/en/M74VHC1GT04DFT1G/M74VHC1GT04DFT1GOSCT-ND/1967056

I just purchased some of these myself.

Procast

Thanks Duane for the tip, 4 cents at RS components

Chris Savage

An NPN transistor can help you invert the output of your signal. This works just fine on the PIR sensor at 3.3V as well. Emitter to ground. PIR output to Base via 220 ohm resistor. Collector to 3.3V via 10K resistor. Collector to device input. The input is now inverted. Of course, if you were going to a microcontroller you could invert it in code much easier.

Procast

I'll have to fix it in hardware.
The sensor is connected to a mediaplayer
They can detect high and low signals but if you want to do a continious detection they only work on low signals.

The sensors trigger the mediaplayer to start playing. Problem at this moment is that if people stay moving in the detection area's the signal stay's high and the movie does'nt start anymore.