Hi,
I am building a motion sensor based lamp that stays on for 10mins and then turns off. My problem is that the lamp turns on when motion is detected but does not seem to turn off.
This is how my circuit is connected:
Motion sensor output goes to a transistor which inverts the sensor output (555 monostable is triggered for input low). This triggers the 555 timer and the output of the timer goes high. This output is connected to a relay (through a diode and a protection diode) which turns the lamp on/off.
I checked the voltage across the capacitor (the R and C of the timer) and it seems to have gone from 0 to Vcc and yet the output has not gone low as it should have for monostable mode.
Can anyone tell me why this could be happening?
Thanks,
Mariam
I am building a motion sensor based lamp that stays on for 10mins and then turns off. My problem is that the lamp turns on when motion is detected but does not seem to turn off.
This is how my circuit is connected:
Motion sensor output goes to a transistor which inverts the sensor output (555 monostable is triggered for input low). This triggers the 555 timer and the output of the timer goes high. This output is connected to a relay (through a diode and a protection diode) which turns the lamp on/off.
I checked the voltage across the capacitor (the R and C of the timer) and it seems to have gone from 0 to Vcc and yet the output has not gone low as it should have for monostable mode.
Can anyone tell me why this could be happening?
Thanks,
Mariam