I bought some of the HC-SR501 PIR's trying to build some motion lights. I am trying to run 25 green led's with this through a 2N2222 transistor. All the led's have a 150 ohm resistors. The ground for the led's is connected to the collector, emitter to ground, and base to the output of the HC-SR501 with a resistor. I have no trouble getting the led's to switch on when feeding the base of the transistor 3.5 volts. I am trying to run this on 6 volts 4 C batteries. I have tried it with varying voltages to no avail. So far all this has done is blink about every 30 seconds or less. I have tried 4 different HC-SR501's, all with the same results. Can anyone tell me what I am doing wrong here?