Hi all, I’m working on a basic circuit and am looking for some quick advice with some trouble I’m having. I tried mocking this up on a breadboard viz as it’s easier for me to visualise than a schematic (tool didn’t have PIR sensor option so added that manually).
I want to turn on an LED strip when the PIR sensor detects motion (set to multiple trigger mode). The LED strip and PIR run on two different voltages. I’m showing two power sources here but will try using a linear regulator when this is sorted. The PIR sends 3.3v HIGH signal to the 2N2222 NPN transistor (which should allow the 24V to flow to the LEDs.
I cannot get the light to turn on! I’ve isolated down to the transistor and have Googled and tried as much as I can. The signal is >10% of the Collector voltage so that shouldn’t be an issue. It was also my understanding that the CBE pins run from left to right with the flat side facing me, but realised the 2N2222 is apparently the opposite. So I’ve tried two of the same type in both orientations.
I’ve measured the voltage coming from the emitter during the PIR trigger to be around 17V, and perhaps 10V when off. I’ve gotten these random voltages in both orientations of the transistor. I don’t understand how the emitter could be lower than the collector. Does anything stand out as being wrong here?
I’ve used this guide as a reference, and haven’t used any resistors as they seemed to be for the individual LED and buzzer.