how can we make the buzzer keep buzzing until it is reset the person can pass the beam quickly and you might not be sure you heard a beep and also the sound will probably make them run away
Patrick! U think u could make same circuit adding a mechanism to let buzzer beep continuously until resetting it...therefore adding a reset switch ! ???
No that would require a capacitor, this is just a simple potential divider system with Vout being controlled by a ldr, the current going into the base gets amplified which helps get a better frequency for the buzzer at the collector
excuse me but im getting it in the reverse order!!! when the laser hits the LDR it lightly beeps if nothing is shone to the LDR there is just silence pls tell the solution
+BEES Gab I tried that but it gives me no more than 2 seconds. I would like it stay on for 20 or 30 seconds.I can use a DPDT Relay and make I stay on till reset, but like I said I would like it to stay on 30 seconds and then reset itself (without Arduino)
Replace buzzer with input if 555 time in monostable mode. Output from 555 drives the buzzer instead. The resistor and capacitor in the 555 will determine how long the buzzer stays on.
The technical explanation is not correct. An npn base to emitter juntion acts as a diode and will not allow the voltage to go to 4.5v as is mentioned in the video. It will stay at about 0.7..0.8v,. Instead of vbe to go to 4.5v, the base-emitter current will increase and active the npn.
