How to avoid false detection when using IR object detection circuit?
Take advantage of the reset pin to delay turn-ON time until Vcc is stable. It is the initial rising of Vcc 5 volts that causes glitches. With the values shown there is a turn-on delay of about 100 ms. The diode discharges C1 instantly so a quick power-up is still delayed.
Also, use CMOS TLC555 which does not have giant glitches at the outputs when changing states. Each 555 must have a 100 nF decoupling capacitor across its power and GND pins.
NOTE: Because the output is inverted, so are the problems. Remove any time delay at the 555 and use it to delay the output going high by using a AND gate and spare inverter gates. This way only the final output signal is blocked until glitches settle down. I understand why you had to invert the output, so it is best to block it until power is stable.



simulate this circuit &ndash; Schematic created using CircuitLab